Patent Publication Number: US-2023135750-A1

Title: Device and method for providing augmented reality interaction

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device and method for providing augmented reality interaction. Specifically, the present invention relates to a device, a method, and a computer program product for providing augmented reality interaction. 
     BACKGROUND OF THE INVENTION 
     Augmented Reality (AR) is a technology for enhancing a real-world environment with virtual computer-generated information. As opposed to virtual reality (VR), AR does not replace the real-world with a computer-generated world, but adds computer-generated information to the real-world, often by overlaying virtual content onto real-world objects. The virtual content can encompass not only visual content (e.g. digital images and models) which are overlaid onto real-world objects, enhancing the visual experience of the real-world, but can also encompass auditory content, haptic content, olfactory content, and content involving other sensory modalities. Additionally, augmented reality can include representations of other users, enabling an interaction between users which goes beyond typical video or telephone conferencing by introducing spatial and contextual aspects to the representation and the interaction. 
     Communication devices for playing back augmented reality content are plentiful and varied and undergoing constant development. Communication devices can be fixedly installed or carried or worn by a user. These communication devices include holographic projection systems, video conferencing systems, personal computers, as well as mobile communication devices. The communication devices can comprise various sensors and displays, as well as wearable modules, such as headsets with eyepieces, smart-glasses, or the like, which present augmented reality content to the user in addition to real world content. The communication devices may be supported by additional connected devices for augmented reality interaction, such as headphones for auditory content and gloves for providing precise motion tracking and haptic feedback. 
     For ensuring the privacy of augmented reality interaction, it is essential a given user, or a given server, can control which other users can be interacted with. 
     For large-scale augmented reality environments, in particular ones involving federated systems, it is not practical or desired to centrally control augmented reality interaction. In particular, this is because for a fluid and natural interaction between the users and the servers, a low latency and high data transmission rates connection becomes critical. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a device and method for providing augmented reality interaction. Specifically, the present invention relates to a device, a method, and a computer program product for providing augmented reality interaction to a user of a communication device. 
     According to the present invention, these objects are achieved through the features of the independent claims. In addition, further advantageous embodiments follow from the dependent claims and the description. 
     According to the present invention, the above-mentioned objects are particularly achieved by a communication device, comprising an electronic circuit configured to obtain location information of a first user of the communication device. The location information can relate to a physical location, e.g. a geographic location determined by GPS. The location information can also relate to an emulated location, i.e. a location in the real world or a virtual world which is distinct from the physical location of the user. The communication device is configured to transmit a query request via a communication network to a computerized virtual real estate directory system, the query request comprising at least the location information of the first user. The communication device is configured to receive from the virtual real estate directory system via the communication network a query response, the query response comprising one or more virtual real estate objects assigned to a virtual real estate object location within a predefined region defined by the location information of the first user, each of the virtual real estate objects comprising identification information and a network address of an augmented reality interaction server. The communication device is configured to transmit for at least one particular virtual real estate object an interaction request via the communication network to one of the augmented reality interaction servers, respectively using the network address of the augmented reality interaction server, each interaction request comprising the identification information of the particular virtual real estate object, and receive from the augmented reality interaction server via the communication network access authorization for the particular virtual real estate object. The communication device is configured to transmit first user data to a communication device of a second user, associated with the particular virtual real estate object, via the augmented reality interaction server, and receive second user data from the communication device of the second user via the augmented reality interaction server. 
     In an embodiment, the communication device is configured to transmit the first user data to the communication device of the second user and receive the second user data from the communication device of the second user, via the augmented reality interaction server, in real time, such that a natural interaction is between the first user and the second user is enabled. 
     In an embodiment, the electronic circuit is configured to transmit a public user identifier of the first user to the augmented reality interaction server comprising one or more of the following: a public name of the first user or an encryption key of the first user. 
     In an embodiment, the electronic circuit is configured to receive, from the augmented reality interaction server a public user identifier of the second user comprising one or more of the following: a public name of the second user or an encryption key of the second user. 
     In an example, the encryption key of the first user is a public key of a public/private key pair generated in the electronic circuit of the communication device of the first user, and the encryption key of the second user is a public key of a public/private key pair generated in the communication device of the second user. 
     In an embodiment, the electronic circuit is configured to receive. from the augmented reality interaction server, a session key generated in the augmented reality interaction server and encrypted by the augmented reality interaction server using the public key of the first user, which session key is decrypted in the communication device of the first user using a private key of the first user. The electronic circuit is configured to encrypt data transmitted to the augmented reality interaction server using the session key, and to decrypt data received from the augmented reality interaction server using the session key. 
     In an embodiment, the electronic circuit is configured to encrypt data transmitted to the communication device of the second user, via the augmented reality interaction server, using the public key of the second user. In an embodiment, the electronic circuit is configured to decrypt data received from the communication device of the second user, via the augmented reality interaction server, which data was encrypted using the public key of the first user, using a private key of the first user stored in the communication device of the first user. 
     In an embodiment, the electronic circuit is configured to digitally sign data transmitted to the augmented reality interaction server or data transmitted to the communication device of the second user via the augmented reality interaction server. In particular, the electronic circuit is configured to sign data to be transmitted using the private key stored in the communication device of the first user, such that the augmented reality server and/or the communication device of the second user are enabled to verify the authenticity of the transmitted data by using the public key of the communication device of the first user. 
     In an embodiment, the electronic circuit is configured to verify the authenticity of data received from the augmented reality interaction server and/or data received from the communication device of the second user using a public key received from the augmented reality interaction server and/or a public key received from the communication device of the second user, respectively 
     In an embodiment, the communication device comprises one or more cameras and a rendering system. The electronic circuit is configured to determine visual representation data of the first user using one or more images of the first user captured by the one or more cameras. The electronic circuit is configured to transmit the visual representation data of the first user, included in the first user data, to the communication device of the second user via the augmented reality interaction server, receive, via the augmented reality interaction server, from the communication device of the second user visual representation data of the second user, included in the second user data; and render, using the rendering system and the visual representation data of the second user, augmented reality content comprising a visual representation of the second user. 
     In an embodiment, the electronic circuit is further configured to determine a field of view of the first user using the one or more cameras, determine from the field of view coordinates of real-world features in the field of view, and render the augmented reality content using the rendering system such that the augmented reality content has a fixed position relative to the coordinates of the real world features. 
     In an embodiment, the electronic circuit is further configured to verify whether the augmented reality content is entirely contained within a bounding volume of the virtual real estate object responsive to positive verification, render the augmented reality content, and responsive to negative verification to either: not render the augmented reality content, or modify the augmented reality content and render modified augmented reality content fitting within the bounding volume of the virtual real estate object. 
     In an embodiment, the communication device further comprises a motion tracker and the electronic circuit is further configured to record user motion data related to body motion of the first user using the motion tracker. The electronic circuit is further configured to transmit the user motion data, included in the first user data, to the augmented reality interaction server. 
     In an embodiment, the communication device further comprises one or more microphones and one or more speakers and the electronic circuit is configured to record audio data of the first user, using the one or more microphones, transmit the audio data of the first user, included in the first user data, to the augmented reality interaction server; receive from the communication device of the second user audio data of the second user, included in the second user data; and play, on the one or more speakers, the audio data of the second user. 
     In an embodiment, the electronic circuit is further configured to receive an augmented reality object from the augmented reality interaction server and render augmented reality content comprising the augmented reality object using the rendering system. The electronic circuit is configured to determine user interaction data of the first user interacting with the augmented reality object and transmit the user interaction data to the augmented reality interaction server. The electronic circuit is configured to receive an updated augmented reality object from the augmented reality interaction server and render the augmented reality content comprising the updated augmented reality object using the rendering system. 
     In addition to a communication device, the present invention also relates to a method of interaction in augmented reality for a first user of a communication device having an electronic circuit, the method comprising obtaining location information of the first user of the communication device and transmitting from the communication device a query request via a communication network to a computerized virtual real estate directory system. The query request comprises at least the location information of the first user ( 2 ). The method comprises receiving in the communication device from the virtual real estate directory system via the communication network a query response. The query response comprises one or more virtual real estate objects assigned to a virtual real estate object location within a predefined region defined by the location information of the first user. Each of the virtual real estate objects comprises identification information and a network address of an augmented reality interaction server. The method comprises transmitting from the communication device for at least one particular virtual real estate object an interaction request via the communication network to one of the augmented reality interaction servers, respectively using the network address of the augmented reality interaction server, each interaction request comprising the identification information of the particular virtual real estate object. The method comprises receiving in the communication device from the augmented reality interaction server via the communication network access authorization for the particular virtual real estate object. The method comprises transmitting from the communication device first user data to a communication device of a second user, associated with the particular virtual real estate object, via the augmented reality interaction server; and receiving in the communication device second user data from the communication device of the second user via the augmented reality interaction server. 
     In an embodiment, the method further comprises transmitting from the communication device the first user data to the communication device of the second user and receiving the second user data from the communication device of the second user, via the augmented reality interaction server in real time. 
     In an embodiment, the method further comprises transmitting, from the communication device of the first user, a public user identifier of the first user to the augmented reality interaction server comprising one or more of the following: a public name of the first user or an encryption key of the first user. 
     In an embodiment, the method further comprises receiving, in the communication device of the first user, from the augmented reality interaction server a public user identifier of the second user comprising one or more of the following: a public name of the second user or an encryption key of the second user. 
     In an example, the encryption key of the first user is a public key of a public/private key pair generated in the electronic circuit of the communication device of the first user, and the encryption key of the second user is a public key of a public/private key pair generated in the communication device of the second user. 
     In an embodiment, the method comprises receiving, in the communication device of the first user, from the augmented reality interaction server, a session key generated in the augmented reality interaction server and encrypted by the augmented reality interaction server using the public key of the first user, which session key is decrypted in the communication device of the first user using a private key of the first user. The electronic circuit is configured to encrypt data transmitted to the augmented reality interaction server using the session key, and to decrypt data received from the augmented reality interaction server using the session key. 
     In an embodiment, the method comprises encrypting, in the communication device of the first user, data transmitted to the communication device of the second user, via the augmented reality interaction server, using the public key of the second user. In an embodiment, the method comprises decrypting, in the communication device of the first user, data received from the communication device of the second user, via the augmented reality interaction server, which data was encrypted using the public key of the first user, using a private key of the first user stored in the communication device of the first user. 
     In an embodiment, the method comprises digitally signing data transmitted to the augmented reality interaction server or data transmitted to the communication device of the second user via the augmented reality interaction server. In particular, the method comprises digitally data to be transmitted using the private key stored in the communication device of the first user, such that the augmented reality server and/or the communication device of the second user are enabled to verify the authenticity of the transmitted data by using the public key of the communication device of the first user. 
     In an embodiment, the method comprises verifying the authenticity of data received from the augmented reality interaction server and/or data received from the communication device of the second user using a public key received from the augmented reality interaction server and/or a public key received from the communication device of the second user, respectively. 
     In an embodiment, the communication device comprises one or more cameras and a rendering system and the method further comprises determining in the communication device visual representation data of the first user using one or more images of the first user captured by the one or more cameras. The method comprises transmitting from the communication device of the first user the visual representation data of the first user, included in the first user data, to the communication device of the second user via the augmented reality interaction server. The method comprises receiving in the communication device of the first user, from the communication device of the second user, via the augmented reality interaction server, visual representation data of the second user included in the second user data. The method comprises rendering, using the rendering system and the visual representation data of the second user, augmented reality content comprising a visual representation of the second user. 
     In an embodiment, the method further comprises determining, in the communication device, a field of view of the first user using the one or more cameras. The method comprises determining, in the communication device, from the field of view coordinates of real-world features in the field of view and rendering, using the rendering system, the augmented reality content such that the augmented reality content has a fixed position relative to the coordinates of the real world features. In particular, the coordinates of the augmented reality content, for example coordinates of a center of the augmented reality content, are associated with the coordinates of the real-world features such that if the real-world features move or rotate, the augmented reality content moves or rotates, respectively, with the real world feature to remain at a fixed position and orientation relative to the position and orientation of the real-world feature. This results in a visually coherent and stable augmented reality environment. 
     In an embodiment, the method further comprises verifying, in the communication device, whether the augmented reality content is entirely contained within a bounding volume of the virtual real estate object. The method comprises rendering the augmented reality content, responsive to positive verification, and responsive to negative verification either not rendering the augmented reality content, or modifying, in the communication device the augmented reality content and rendering modified augmented reality content fitting within the bounding volume of the virtual real estate object. 
     In an embodiment, the communication device further comprises a motion tracker and the method further comprises recording, in the communication device user motion data related to body motion of the first user using the motion tracker. The method comprises transmitting, from the communication device, the user motion data, included in the first user data, to the augmented reality interaction server. 
     In an embodiment, the communication device further comprises one or more microphones and one or more speakers and the method comprises recording, in the communication device, audio data of the first user, using the one or more microphones. The method comprises transmitting, from the communication device, the audio data of the first user, included in the first user data, to the augmented reality interaction server. The method comprises receiving, in the communication device, audio data of the second user from the communication device of the second user, included in the second user data and playing, on the one or more speakers, the audio data of the second user. 
     In an embodiment, the method further comprises receiving, in the communication device an augmented reality object from the augmented reality interaction server, rendering augmented reality content comprising the augmented reality object using the rendering system. The method comprises determining, in the communication device, user interaction data of the first user interacting with the augmented reality object and transmitting, from the communication device the user interaction data to the augmented reality interaction server. The method comprises receiving, in the communication device an updated augmented reality object from the augmented reality interaction server and rendering the augmented reality content comprising the updated augmented reality object using the rendering system. 
     In addition to a computer device and a method of interaction in augmented reality, the present invention also relates to a computer program product comprising a non-transitory computer-readable medium having stored thereon computer program code configured to control an electronic circuit of a communication device such that the communication device performs the method as described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be explained in more detail, by way of example, with reference to the drawings in which: 
         FIG.  1   : shows a block diagram illustrating schematically a communication device for providing augmented reality interaction. 
         FIG.  2   : shows a diagram illustrating schematically a first user with a first communication device, a computerized virtual real estate directory system, augmented reality interaction servers, and the networks lying there between. 
         FIG.  3   : shows a diagram illustrating schematically a first user with a first communication device, an augmented reality interaction server, a second user with a second communication device, and the networks lying there between. 
         FIG.  4   : shows a drawing illustrating schematically a plan view with a user in an urban environment comprising virtual real estate objects. 
         FIG.  5   : shows a drawing illustrating schematically a field of view of a first user in an interior environment comprising a communication device, a visual representation of a second user, and an augmented reality object. 
         FIG.  6   : shows a block diagram illustrating schematically a virtual real estate directory system. 
         FIG.  7   : shows a block diagram illustrating schematically an augmented reality interaction server comprising augmented reality objects. 
         FIG.  8   : shows a flow diagram illustrating a sequence of steps for providing augmented reality interaction. 
         FIG.  9   : shows a flow diagram illustrating a sequence of steps for rendering a visual representation of a second user. 
         FIG.  10   : shows a flow diagram illustrating a sequence of steps for rendering an augmented reality object to a first and a second user. 
         FIG.  11   : shows a flow diagram illustrating modification of augmented reality content. 
         FIG.  12   : shows a block diagram illustrating modification of augmented reality content. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG.  1   , reference numeral  1  refers to a communication device  1  comprising an electronic circuit  13 . Depending on the embodiment, the communication device  1  includes various further modules, such as a rendering system  11 , one or more cameras  12 , one or more speakers  4 , one or more microphones  15 , a motion tracker  16 , a memory, a communication interface, a battery, an orientation module, and/or a user interface. The rendering system  11  is configured to display visual content two-dimensionally and/or three-dimensionally. The rendering system  11  can, depending on the embodiment, comprise a holographic projection system, one or more projectors, and/or a display. The user interface can be integrated into the rendering system  11  in the form of a touch-sensitive display. The communication device  1  can, depending on the embodiment, comprise further modules, such as a GPS module, accelerometer, and an environmental module (for measuring temperature and/or humidity). Further, the communication device  1  can be connected to a building automation system, for example for controlling lights, doors, and/or HVAC systems. The communication device  1  can also be connected to other Internet of things (IoT) devices. The modules of the communication device  1  are connected to each other via a data connection mechanism, such that they can transmit and/or receive data. Alternatively, or in addition, one or more of the modules of the communication device  1  are integrated into the electronic circuit  13 . The communication interface of the communication device  1  is configured for wireless communication with remote servers via a communication network  3 . The communication network  3  comprises the Internet as well as other intermediary networks. The wireless communication takes place using a mobile data network, such as GSM, CDMA and LTE networks, and/or a close range wireless communication interface using a Wi-Fi network, Bluetooth, and/or other wireless network types and standards. In an embodiment, the communication device  1  further comprises accessory modules, including headphones, displays, such as head-mounted displays and/or smart-glasses, and/or haptic gloves. These accessory modules are configured to exchange data with the communication device  1  via a data connection mechanism. 
     The term data connection mechanism relates to a mechanism that facilitates data communication between two components, devices, systems, or other entities. In an embodiment, the data connection mechanism is wired, such as a cable or system bus. In an embodiment, the data connection mechanism includes wireless communication, such that some components of the communication device are physically separated from each other and exchange data with each other wirelessly, using a Bluetooth standard, for example. 
     Depending on the embodiment, the electronic circuit  13  comprises a system on a chip (SoC), a central processing unit (CPU), and/or other more specific processing units such as a graphical processing unit (GPU), application specific integrated circuits (ASICs), reprogrammable processing units such as field programmable gate arrays (FPGAs), as well as processing units specifically configured to accelerating certain applications, such as AI (Artificial Intelligence) accelerators for accelerating neural network and/or machine learning processes. 
     The memory comprises one or more volatile and or non-volatile storage components. The storage components may be removable and/or non-removable, and can also be integrated, in whole or in part with the communication device  1 . Examples of storage components include RAM (Random Access Memory), flash memory, hard disks, data memory, and/or other data stores. The data storage system comprises a non-transitory computer-readable medium having stored thereon computer program code configured to control the electronic circuit  13 , such that the communication device  1  performs one or more steps and/or functions as described herein. Depending on the embodiment, the computer program code is compiled or non-compiled program logic and/or machine code. As such, the communication device  1  is configured to perform one or more steps and/or functions. The computer program code defines and/or is part of a discrete software application. One skilled in the art will understand, that the computer program code can also be distributed across a plurality of software applications. In an embodiment, the computer program code further provides interfaces, such as APIs (Application Programming Interfaces), such that functionality and/or data of the mobile communication device  1  can be accessed remotely, such as via a client application or via a web browser. In an embodiment, the computer program code is configured such that one or more steps and/or functions are not performed in the communication device  1  but in a separate computer system, remote from the communication device  1 . 
     In an embodiment, the communication device  1  is a personal computer. The personal computer, for example a laptop running the Windows operating system, is configured to install the computer program code, for example from a portable medium or from a server. 
     In an embodiment, the communication device  1  is a mobile phone. The mobile phone, for example a smart-phone running the Android operating system or the iOS operating system, is configured to download and install the computer program code from a server, for example from an App store. Further examples of mobile communication devices  1  are tablet computers, smartwatches and the like. 
     In an embodiment, the one or more speakers  14  are configured to play back auditory content, and comprise an electro-acoustic transducer, such as a loudspeaker or a headphone. The auditory content can be played back by speakers  14  arranged in a mono, stereo, or multichannel configuration. Further, spatial and 3D audio can also be played back, depending on the auditory content and the configuration of the speakers  14 . 
     The orientation module of the communication device  1  captures the orientation of the first user  2  and/or of the communication device  1  and can comprise a compass, accelerometers, gyroscopic sensors, etc. 
     The user interface enables the first user  2  to interact with the communication device  1 . In particular, the user interface enables the first user  2  to enter data into the mobile communication device  1 . Examples of the user interface comprise a touch-sensitive display and hardware buttons such as a keyboard. The one or more microphones  15  are configured to capture audio, for example configured for capturing voice commands of the first user  2 . In an embodiment, the user interface further uses other modules, such as the one or more cameras  15  and/or the motion tracker  16 , for capturing movement and/or gestures of the first user  2  as user input. The motion tracker  16  can include a held or worn device which tracks the motion of the first user  2  or part of the body of the first user  2 . 
       FIG.  2    shows a diagram illustrating schematically the first user  2  with the communication device  1 , a computerized virtual real estate directory system  4 , augmented reality interaction server  5 , and the communication network  3  via which communication takes place between the communication device  1  and the virtual real estate directory system  4 , and the communication device  1  and the augmented reality interaction servers  5 . Transmissions T 2 , T 3 , T 5 , and S 6  are also shown and are explained below in more detail with reference to  FIG.  8   . The first user  2  carries, on his or her person, the communication device  1 . 
     In an embodiment where the communication device  1  is a wearable device, the first user  2  wears the communication device  1 , for example as a headpiece or eyepiece. In an embodiment where the communication device  1  is not portable, and is, for example, fixedly installed, the first user  2  is situated near the communication device  1 . 
     By separating the virtual real estate directory system  4  and the augmented reality interaction server  5 , the virtual real estate directory system  4  can be configured for quick and efficient determining of virtual real estate objects  41  (not shown). The ownership and governance of the virtual real estate directory system  4  is therefore separated from the ownership and governance of the augmented reality interaction server  5 . The virtual real estate directory system  4  provides relatively little data to the communication device  1 , whereas the augmented reality interaction server  5  exchanges relatively larger amounts of data with the communication device  1 . Therefore, a relatively denser and more local provision of augmented reality interaction servers  5  than servers of the virtual real estate directory system  4  enable an efficient distribution of servers and enable the relatively larger amounts of data to be exchanged via the augmented reality interaction servers  5  to the communication device  1  with lower transmission latency and greater bandwidth, enabling a more natural and responsive interaction. In particular, the augmented reality interaction server  5  is located at a physical location which corresponds to the location of the virtual real estate object. In this way, users physically located at the same location as the augmented reality interaction server  5  benefit from a low latency connection. 
       FIG.  3    shows a diagram illustrating schematically a first user  2  with a first communication device  1  connected to the augmented reality interaction server  5  via the communication network  3  and a second user  2 B with second communication device  1 B also connected to the augmented reality interaction server  5  via the communication network  3 . Both the first user  2  and the second user  2 B are located in the same virtual real estate object  41 . 
     In an embodiment, the first user  2  and the second user  2 B are located in different virtual real estate objects  41  which are adjacent or near each other. Transmissions T 7 , T 8 , T 7 B, and T 8 B are also shown and are explained below in more detail with reference to  FIG.  8   . 
       FIG.  4    shows a drawing illustrating schematically a plan view of an urban environment comprising virtual real estate objects  41  and the first user  2  at a location described by location information  21 . 
     In an embodiment, the location information  21  is a physical geographic location of the first user  2  which, for example, is described by coordinates in a coordinate system. For example, the coordinate system is a geographic coordinate system described by spherical coordinates, i.e. latitude and longitude, projected coordinate systems, such as universal transverse Mercator (UTM) or the like. National coordinate systems, such as the Swiss coordinate system, can also be used to describe the location information  21  of the first user  2 . In an embodiment, corrections to the location information  21  of the first user  2  are provided to compensate for continental drift. 
     In an embodiment, the location information  21  relates to an emulated location of the first user  2 , meaning that the first user  2  is not actually physically present at that location, but rather a representation of the first user  2  has been placed at the physical location. For example, the first user  2  has selected the representation of the first user  2  to be virtually located at the location  2 . For example, the first user  2  may be physically located at their home, while the emulated location information  21  of the first user  2  is located at his or her workplace. 
     A region R around the first user  2  is defined as a two-dimensional or three-dimensional space in which the first user  2  is located. Depending on the embodiment or configuration, the region R is a geometric object such as a sphere centered on the location as described by the location information  21  of the first user  2 , or a rectangle with the first user  2  placed inside. In an embodiment, the region R is defined in terms of a direction in which the first user  2  is oriented, such that the region R extends further from the first user  2  in the direction in which the first user  2  is oriented (e.g. facing and/or looking) than in the directions in which the first user  2  is not oriented. 
     The real-world space is virtually divided into a hierarchy of virtual real estate objects  41  arranged similarly to a tree data structure, and in which parent virtual real estate objects comprise child virtual real estate objects. The hierarchy comprises a plurality of levels. Virtual real estate objects  41  at higher levels cover larger geographic areas, such as a country, state, or city. Virtual real estate objects  41  at lower levels cover smaller areas, such as city squares, blocks, buildings. At even lower levels, virtual real estate objects  41  cover even smaller spaces such as stories of buildings, shops, individual rooms, and/or individual compartments or shelves in rooms. For the purposes of illustration, a plurality of virtual real estate objects  41  are shown in  FIG.  4   . In one example, the virtual real estate objects  41  are 3D objects defined by a set of polygons, a set of edges and vertices, and/or voxels. In another example, virtual real estate objects  41  are 2D objects described by a set of lines and/or a set of points which define a virtual fence around the virtual real estate object  41 . 
     Each virtual real estate object  41  is assigned a virtual real estate object location  42  in the virtual real estate directory system  4 , which associates the virtual real estate object  41  with a real-world location whereby the virtual real estate object location  42  is described by coordinates in a coordinate system. As above for the location information  21  of the first user  2 , the coordinate system uses, for example, spherical coordinates or projected coordinates, based on a local or national coordinate system. In an embodiment, the coordinates are further corrected to account for continental drift or other sources of error. 
     Each virtual real estate object  41  has a bounding volume V which is a closed volume which contains the virtual real estate object  41 . The bounding volume V is defined using polygons, vertices and edges, and/or other geometric objects. The bounding volume V being a closed volume means that a given point cannot move from inside the bounding volume V to outside the bounding volume V without passing through a surface of the bounding volume V. 
     In one example, the bounding volume V exactly matches the shape of the virtual real estate object  41 . In another example, the bounding volume V is a relatively simpler shape than the relatively more complex virtual real estate object  41 , meaning it is described with less polygons and/or less vertices and edges than the virtual real estate object  41 . However, it is ensured that the bounding volume V entirely contains the virtual real estate object  41 , e.g. no points of the virtual real estate object  41  lie outside the bounding volume V. In an embodiment, the bounding volume V is a rectangular prism. 
       FIG.  5    shows a drawing illustrating schematically a field of view F of the first user  2  in an indoor environment. The field of view F is indicated by the dashed lines. The field of view F is defined, for example, by a solid angle with its vertex at the first user  2  or at the communication device  1 . Alternatively, the field of view is defined as a rectangular pyramid with a horizontal angle and vertical angle and a vertex at the first user  2 . The location of the first user  2  is defined by the location information  21 . The first user  2  is situated in front of a table. Multiple cameras  12  capture images of the first user  2  from multiple angles. One or more microphones  15  capture audio data of the first user  2 . The rendering system  11  renders augmented reality content  51 , which comprises augmented reality content  53  and user data received from users with which the first user  2  is interacting, in particular from the second user  2 B. The augmented reality content  51  rendered comprises visual augmented reality content, as well as auditory augmented reality content. The augmented reality content  51  can further comprise other sensory modalities, for example touch, smell, or taste, depending on the capabilities of the particular rendering system  11 . 
     Depending on the embodiment, the user data received comprises a visual representation  54  of the second user  2 B rendered by the rendering system  11 , and auditory augmented reality content played back by the one or more speakers  14 . 
     In an embodiment, the augmented reality object  53  comprises visual content, e.g. a 3D model described by a set of polygons, along with auditory content, e.g. as described by an audio track. In an embodiment, beyond the 3D model, augmented reality content  51  comprises dynamic content, interactive content with which the first user  2  can interact, and so forth. 
     The augmented reality content  51  is rendered for the first user  2  using the communication device  1 . Depending on the particular hardware configuration of the communication device  1 , e.g. which type of device the mobile communication device  1  is, which modules the communication device  1  comprises, and which accessory modules the communication device  1  is connected to, the rendering of the augmented reality content  51  comprises rendering and/or playing back one or more types of sensory content. 
     The augmented reality content  51  is rendered by the rendering system  11  such that it remains in a fixed position relative to the table. In particular, the cameras  12  extract coordinates C of the environment of the first user  2 , for example the table, from the field of view F of the first user  2 . The communication device  1  then renders the augmented reality content  51  in the air such that it does not move relative to the real world objects in the environment, such as the table. 
     In an embodiment, the rendered augmented reality content  51  is anchored to a real world object, for example a feature of the building, such as a floor, wall, or other surface of the building, or for example an item of furniture, such as a table. The augmented reality content  51  is rendered such that it remains in a fixed position relative to the real world object such that even if the first user moves their head or body the augmented reality content  51  will remain in place in the 
     Using the field of view F, in an embodiment, coordinates C are overlaid onto the real-world, enabling coordinates of real-world objects and features to be extracted from the field of view F. For example, the cameras  12  of the communication device  1  capture the field of view F as one or more images, and the communication device  1  extracts from the one or more images points, edges, and other features of real-world objects, such as corners of buildings, street edges, the horizon, and other persons, and stores these extracted features. The extracted features are used by the communication device  1 , for example, to improve a calculated location of the first user  2 , improve a determined orientation of the first user  2 , and/or improve the positioning and rendering of augmented reality content  51 . 
     In an embodiment, the field of view F is defined using a field of view of the camera  12  of the mobile communication device  1 . Additionally, an accelerometer and/or gyroscopic sensor of the communication device  1  are used by the communication device  1  to determine an orientation of the communication device  1 . The orientation of the communication device  1  is then used to determine the field of view F. 
     In an embodiment, the field of view F is defined as the field of view of the first user  2  by determining, using the orientation module of the communication device  1 , an orientation of the first user  2 , for example a body orientation of the first user  2 , a head orientation of the first user  2 , and/or an eye orientation of the first user  2 . Depending on the embodiment, the orientation module of the communication device  1  comprises a head-tracker, eye-tracker, or other component(s) to detect an orientation of the first user  2 . 
       FIG.  6    shows a block diagram illustrating schematically a virtual real estate directory system  4 . The virtual real estate directory system  4  is implemented using a server computer system comprising one or more server computers. The server computers of the virtual real estate directory system  4  are located at the same location or are distributed, i.e. located remotely from one another at different locations. The server computers of the virtual real estate directory system  4  comprise one or more processors, memory, and communication interfaces for exchanging data with other systems and/or devices using the communication network  3 . For example, the virtual real estate directory system  4  exchanges data with the mobile communication device  1  using the communication network  3 . The virtual real estate directory system  4  is implemented on server computers as a hierarchical system and/or hierarchical database which comprise virtual real estate objects  41 . 
     As explained above in relation to  FIG.  4   , the real-world space is virtually divided into a hierarchy of virtual real estate objects  41  with virtual real estate objects  41  at higher levels covering large geographic areas, such as a country, state, or city and virtual real estate objects  41  at lower levels covering smaller areas. The virtual real estate directory system  4  is arranged in a similar hierarchy with one or more high level server computers comprising higher level virtual real estate objects  41 , and one or more low level server computers comprising low level virtual real estate objects  41 . In an embodiment, the server computers are located in the same location or area as the virtual real estate objects  41  they store. For example, the server computer comprising virtual real estate objects  41  for a specific country is located in that same country, and the server computer comprising virtual real estate objects  41  for a specific city is located in that same city. 
     The virtual real estate object  41  comprises the virtual real estate object location  42 , identification information  43  which uniquely identifies the virtual real estate object  41 , a network address of an augmented reality interaction server  44 , and the bounding volume V. The identification information  43  comprises at least: an identifier which uniquely identifies the virtual real estate object  41  or a hash value of the virtual real estate object  41 . The hash value is generated by hashing the virtual real estate object  41  or one or more components thereof. Additionally, the virtual real estate object  41  comprises information relating to an owner and/or assignee of the virtual real estate object, and 3D content relating to a more complex boundary of the virtual real estate object  41 . Depending on its hierarchical level, a given virtual real estate object  41  comprises identification information of child virtual real estate objects  41  which are contained in the given virtual real estate object  41 , and identification information of parent virtual real estate objects  41  of which the given virtual real estate object  41  is itself a child virtual real estate object  41 . This enables an efficient mapping and traversing of virtual real estate objects  41  in the virtual real estate directory system  4 . 
     In an embodiment, the identification information  43  comprises and/or defines the bounding volume V. In a further embodiment, the identification information  43  comprises one or more of the following: the identifier, the hash value, the bounding volume V, or the virtual real estate object location  42 . 
       FIG.  7    shows a block diagram illustrating schematically an augmented reality interaction server  5  comprising augmented reality objects  53 . The augmented reality interaction server  5  comprises one or more server computers. The server computers of the augmented reality interaction server  5  comprise one or more processors, memory, and communication interface for exchanging data with other systems and/or devices using the communication network  3 . For example, the augmented reality interaction server  5  exchanges data with the communication device  1  using the communication network  3 . The augmented reality interaction server  5  is separate from the virtual real estate directory system  4 . For example, the augmented reality interaction server  5  is located near the location to which the virtual real estate object  41  is assigned. The augmented reality interaction  51  comprises sensory content of one or more sensory modalities, as described above in relation to  FIG.  4   . 
     In an embodiment, the augmented reality interaction server  5  is located at the same location as the virtual real estate directory system  4  and/or is implemented on servers of the virtual real estate directory system  4 . 
     In an embodiment, the augmented reality interaction server  5  hosts one or more augmented reality rooms. In particular, the one or more processors of the augmented reality interaction server  5  are configured to generate one or more augmented reality rooms. The augmented reality rooms are virtual 3D spaces which are configured such that the first user  2  and the second user  2 B can join the augmented reality room. In an embodiment, the augmented reality rooms correspond to a physical space, such as one or more of: a premises, a building, an auditorium, or a room. The augmented reality interaction server  5  is configured for secure data exchange such that the first user  2 , the second user  2 B, and/or further users can exchange data with each other, securely, within a first augmented reality room, without other users in other augmented reality rooms having knowledge of, or access to, any data being exchanged in the augmented reality room. 
     In a first embodiment, the augmented reality interaction server  5  is configured to generate for the augmented reality room an encryption key. 
     In a first example, the augmented reality interaction server  5  generates a public/private key pair and transmits the public key to the first user  2  and the second user  2 B. The communication device  1  of the first user  2  is configured to receive the public key of the augmented reality room from the augmented reality interaction server  5 . The communication device  1  of the first user  2  is configured to transmit a public key of the communication device  1  to the augmented reality room of the augmented reality interaction server  5 . The communication device  1  is configured to encrypt data transmitted to the augmented reality room using the public key of the augmented reality room, and configured to decrypt data received from the augmented reality room using a private key of the communication device  1 . In such a way, a high level security is provided for data transmitted between the communication device  1  and the augmented reality room. The augmented reality room encrypts data transmitted to the communication device  1  of the first user  2  using the public key of the communication device  1  and encrypts data transmitted to the communication device  1 B of the second user  2 B using a public key of the communication device  1 B of the second user  2 B. 
     In an embodiment, data transmitted from the communication device  1  of the first user  2  to the augmented reality room itself comprises address information comprising one or more of the following: a public name of the second user  2 B, one or more public names of further users, or a public flag. The address information is, depending on the embodiment, encrypted with a public encryption key of the augmented reality room. The augmented reality interaction server  5  is configured to forward the data transmitted from the communication device  1  depending on the address information, in particular to forward the data to all users in the augmented reality room if the address information comprises the public flag, or to a set of users according to the list of public names contained in the address information. 
     Depending on the embodiment, first user data transmitted by the communication device  1  of the first user  2  to the communication device  1 B of the second user  2 B is encrypted with a public key, or a symmetric session key established between the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B, such that the augmented reality room, nor any further users, have access to the unencrypted first user data. The above configurations of the communication between the augmented reality interaction server  5 , the first user  1  and the second user  1 B ensure a high level of security as data is encrypted end-to-end between the first user  1  and the second user  1 B. 
     In an embodiment, the communication device  1  receives from the augmented reality room the encryption key, the encryption key being securely encrypted using the public key of the communication device  1  which was received in the augmented reality room. The communication device  1  is configured to decrypt the encryption key using the private key of the communication device  1 . Subsequently, data transmitted to the augmented reality room by the communication device  1  is encrypted in the communication device  1  using the encryption key. In this embodiment, the encryption key of the augmented reality room acts as a symmetric session key which is securely transmitted to the first user  1 , the second user  1 B, and further users logged in to the augmented reality room. Further users joining the augmented reality room receive the encryption key from the augmented reality room and are subsequently privy to data of the augmented reality room. This configuration allows for fast and secure data exchange between all participants of the augmented reality room. Simultaneously, the communication device  1  is configured such that it can also perform an end-to-end encrypted data exchange with one or more participants of the augmented reality room. 
     In an embodiment, the augmented reality room is configured to generate a new encryption key and distribute the new encryption key to the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B if a further participant of the augmented reality room leaves the augmented reality room. This ensures continued security of the augmented reality room and data being exchanged therein. In particular, the communication device  1  is configured to receive from the augmented reality interaction server  5  a new encryption key, encrypted with the public key of the communication device  1 , to decrypt the new encryption key using the private key stored in the communication device  1 , to replace the stored encryption key with the new encryption key, and to encrypt subsequent data transmitted to the augmented reality interaction server  5  using the new encryption key. 
       FIG.  8    shows a flow diagram illustrating a sequence of steps for providing augmented reality interaction  51  between the first user  2  of the first communication device  1  and the second user  2 B of the second communication device  1 B. 
     In step S 1 , the location information  21  of the first user  2  is obtained. The location information  21  of the first user  2  is obtained by the electronic circuit  13  of the communication device  1 . The location information  21  relates to a physical location of the first user  2  or an emulated location of the first user  2 . The emulated location of the first user  2  corresponds to a location in the real world which the first user  2  has selected, for example by choosing a location on a map, or a location in the real world to which the first user  2  has been assigned, for example by virtue of belonging to a particular group, for example their company. For example, if the first user  2  is located at their home, the first user  2  can select their workplace has their emulated location, and the location information  21  of the first user  2  relates henceforth relates to their emulated location. 
     In an embodiment, the location information  21  relates to a physical location of the first user  2  and the location module of the mobile communication device  1  determines the physical location using signal trilateration, for example from a global navigation satellite system such as GPS (Global Positioning System), Glonass, and/or Galileo. In an embodiment, the location module further uses the presence of other radio networks, such as mobile radio or WLAN networks, to determine the physical location of the first user  2 , for example by trilateration. In an embodiment, the location module further uses beacons, such as Bluetooth or ultra-wideband beacons for determining the physical location of the first user  2 , which is particularly advantageous indoors where a precise determination of the location information  21  of the first user  2  may not be possible using satellite-based systems. The electronic circuit  13  obtains the location from the location module. 
     In an embodiment, a device separate from the communication device  1  of the first user  2  determines the location information  21  of the first user  2  and transmits the location information  21  to the mobile communication device  2 . 
     In step S 2 , the communication device  1  transmits in a transmission T 2  a query request to the virtual real estate directory system  4  using the communication network  3 . The query request comprises the location information  21  of the first user  2 . The query request 
     In an embodiment, the query request further comprises an orientation of the first user  2 , a field of view F of the first user  2 , a user identifier of the first user  2 , a device identifier of the communication device  1 , a network address of the communication device  1 , a device type of the communication device  1 , a hardware configuration of the communication device  1 , and/or a movement velocity of the first user  2  of the communication device  1 . The field of view F of the first user  2  and the device type of the communication device  1  in particular enable the recipient of the query request to provide a relevant and complete query response to the communication device  1 , as is explained below. 
     In step S 201 , the query request is received in the virtual real estate directory system  4  from the communication device  1 . The query request is received in the server computer system. In particular, the query request is received in a specific server computer of the server computer system. 
     In step S 202 , the virtual real estate directory system  4  processes the query request. The query request is processed in the server computer system. Processing the query request comprises the specific server computer of the virtual real estate directory system  4  which received the query request to check whether the query request is to be forwarded to another server computer of the virtual real estate directory system  4 . The query request is to be forwarded depending on one or more of the following factors: the physical location to which the location information  21  of the first user  2  relates, the user identifier of the first user  2 , the device identifier of the communication device  1 , and the network address of the communication device  1 . In particular, depending on the location information  21  of the first user  2 , the query request is forwarded to one or more further server computers of the virtual real estate directory system  4 , which are responsible for the geographic area corresponding to the location information  21  of the first user  2 , meaning that they comprise virtual real estate objects  41  assigned to virtual real estate locations  42  in the geographic area indicated by the location information  21  of the first user  2 . In an embodiment, forwarding the query request in the virtual real estate directory system  4  comprises one or more individual forwarding steps, where a given receiving server computer forwards the query request to one or more further server computers, which in turn process and forward the query result to other server computers. In this manner, the query request traverses the server computers arranged in the hierarchical system and/or hierarchical database. 
     In step S 203 , the virtual real estate directory system  4  generates a query response. The query response comprises virtual real estate objects  41  located near the location defined by the location information  21  (the physical location or the emulated location) of the first user  2 . In particular, the query response comprises virtual real estate objects  41  assigned to a virtual real estate location  42  within the region R around the location defined by the location information  21  of the first user  2 . In an embodiment, the query response comprises virtual real estate objects  41  located in the field of view F of the first user  1 . For example, the query response comprises virtual real estate objects  41  stored on one or more server computers of the virtual real estate directory system  4 . In particular, the query response may comprise a plurality of query response messages from a plurality of server computers of the virtual real estate directory system  4 , each query response message comprising virtual real estate objects  41  assigned to virtual real estate locations  42  within the region R around the location of the first user  2 . For example, a server computer of the virtual real estate directory system  4 , responsible fora city, may generate a query response message with large virtual real estate objects  41  corresponding to city blocks, landmarks, and/or natural geographic features, and another server computer of the virtual real estate directory system  4 , responsible for a particular building, may generate another query response message with smaller virtual real estate objects  41 , corresponding to the particular building along with particular floors, units, and/or areas of the building. 
     In step S 204 , the query response is transmitted, in a transmission T 3 , from the virtual real estate directory system  4  to the communication device  1  via the communication network  3 . The query response is transmitted from the server computer system of the virtual real estate directory system  4  and comprises one or more individual query response messages from one or more server computers of the virtual real estate directory system  4 . 
     In step S 3 , the query response is received in the communication device  1 . The query response comprises one or more virtual real estate objects  41 . Each virtual real estate object  41  comprises the virtual real estate object location  42 , the identification information  43 , the network address  44  of the augmented reality interaction server  5 , and the bounding volume V. 
     In an embodiment, at least one of the query request or the query response are encrypted transmissions. In one example, the query request is encrypted by the communication device  1  using a public key of the virtual real estate directory system  4  obtained by the communication device  1 . In another example, the query response is encrypted by the virtual real estate directory system  4  using a public key of the communication device  1  obtained by the virtual real estate directory system  4 . In another example, the communication device  1  and the virtual real estate directory system  4  establish a secure connection prior to transmission of the query request by the communication device  1 , for example using the Secure Sockets Layer (SSL) protocol. 
     In step S 4 , the query response is processed and stored in the communication device  1 . Depending on the embodiment and/or configuration, processing the query response comprises the communication device  1  using the orientation of the first user  2  and/or the field of view F to generate a sub-set of virtual real estate objects  41  with a virtual real estate object location  42  located in the direction of the orientation of the first user  2  and/or within the field of view F of the first user  2 . Furthermore, processing the query response may comprise the communication device  1  using a movement velocity of the first user  2  to generate a sub-set of virtual real estate objects  41  with a virtual real estate object location  42  located in the direction in which the first user  2  is moving. 
     In an embodiment, the virtual real estate object  41  is displayed using the rendering system  11  of the communication device  1 , such that the virtual real estate object  41  appears on the rendering system  11  overlaid over the real-world in a semi-transparent or translucent manner at the virtual real estate object location  42 . In an embodiment, this comprises displaying the bounding volume V of the virtual real estate object  41 . In particular, when the communication device  1  is situated in an interior environment, the virtual real estate object  41  is displayed around the communication device  1  using the rendering system  11 . For example, if the location information  21  of the first user  2  relates to an emulated location, the virtual real estate object  41  can encompass the first user  2 . 
     The communication device  1  generates an interaction request for each virtual real estate object  41  that the communication device  1  received in the query response. In an embodiment, the communication device  1  generates an interaction request only for those virtual real estate objects  41  of the sub-set of virtual real estate objects  41 . Each particular interaction request comprises the identification information  43  of the particular virtual real estate object  41 . Additionally, each particular interaction request may comprise the user identifier of the first user  2 , the device identifier of the communication device  1 , the network address of the communication device  1 , the device type of the mobile communication device  1 , and/or the hardware configuration of the communication device  1 . 
     In step S 5 , the communication device  1  transmits, in a transmission T 5  via the communication network  3 , one or more interaction requests to one or more augmented reality interaction servers  5  using the specific network address  44  of each specific augmented reality interaction server  5 . Depending on the embodiment and/or scenario, the communication device  1  transmits an interaction requests to each augmented reality interaction server  5 . Subsequent steps are described in relation to a single interaction request and a single augmented reality server  5  for the sake of conciseness. 
     In step S 501 , the augmented reality interaction server  5  receives the interaction request in a transmission T 5 . Access authorization is determined for all augmented reality objects  51  within the virtual real estate object  41 . Further, access authorization relating to augmented reality interaction between the first user  2  and other users, in particular the second user  2 B, is determined. Access authorization for augmented reality interaction ensures that the first user  2  is authorized to interact, in augmented reality, with other users within the virtual real estate object, in particular with a second user  2 B. In particular, access authorization for augmented reality interaction comprises authorization for the first user  2  transmitting first user data to, and receiving second user data from, the second user  2 B. User data (e.g. first user data and/or second user data) comprises data files stored in, or obtained by, the communication device  1 . 
     In an embodiment, the user data further comprises personal data of the user, as well as visual representation data and/or audio data of the user, as explained in more detail below. 
     In an embodiment, different augmented reality objects  53  have different access authorization levels, such that the user  2  is granted access authorization to some, but not necessarily all, augmented reality objects  53 . Depending on the embodiment, the augmented reality interaction server  5  may receive a separate interaction request from the communication device  1  for each augmented reality object  53 . 
     In step S 502 , the augmented reality interaction server  5  determines access authorization of the communication device  1  and/or the first user  2  using the interaction request. In particular, the augmented reality interaction server  5  checks whether a hardware identifier of the communication device  1  contained in the interaction request is authorized. Additionally, credentials of the first user  2  contained in the interaction request, such as a user name and a user password, are verified to determine access authorization. 
     In step S 503 , the augmented reality interaction server  5  transmits an access authorization confirmation in a transmission T 6  to the communication device  1  of the first user  2 . In step S 6 , the communication device  1  receives the access authorization confirmation. 
     In an embodiment, the steps above related to access authorization are carried out over an encrypted communications channel, for example using SSL encryption. Additionally, a particular augmented reality interaction server  5  may require two factor authentication. In one example, the augmented reality interaction server  5  transmits a confirmation code to a separate user device of the first user  2 , the first user  2  being required to enter the confirmation code into the communication device  1 , the confirmation code then being transmitted back to the augmented reality interaction server  5 , whereupon the augmented reality interaction server  5  determines if the confirmation codes match. 
     In an embodiment, the communication device  1  is configured to receive from the augmented reality interaction server  5 , as part of the authorization of step S 6 , a user identifier which is dynamically generated by the augmented reality interaction server  5 . The user identifier is transmitted by the communication device  1  in subsequent data transmissions to the augmented reality interaction server  5 . Depending on the embodiment, the communication device  1  transmits the public name and/or the user identifier of the communication device  1  to the augmented reality interaction server  5 . 
     In an embodiment, the communication device  1  is configured to receive from the augmented reality interaction server  5  a digital certificate, which digital certificate comprises one or more digital credentials of the augmented reality interaction server. The communication device  1  is configured to verify the validity of the digital certificate prior to further communication with the augmented reality interaction server  5 . 
     Subsequent to receiving access authorization, the first user  2  exchanges data with other users who are located in the virtual real estate object  41  via the augmented reality interaction server  5 . In particular, as explained below in more detail, the communication device  1  of the first user  2  exchanges first user data with the communication device  1 B of the second user  2 B via the augmented reality interaction server  5 , the second user  2 B also being located in the virtual real estate object  41 . The communication device  1  thereby enables an exchange of data between the first user  2  and other users who are located, physically or virtually (i.e. a corresponding emulated location) at the virtual real estate object location  42 . This enables a group of users located in or near the virtual real estate object  41  to interact in augmented reality. 
     In an embodiment, subsequent to receiving access authorization, the communication device  1  of the first user  2  receives from the augmented reality interaction server  5  a room list of one or more augmented reality rooms, and can receive along with a room name of a particular augmented reality room a user list of all user currently in the particular augmented reality room. The communication device  1  is configured to enable the first user  2  to select a particular augmented reality room. Upon selection of the particular augmented reality room, the first user  2  performs an exchange of credentials, for example an exchange of public keys or establishing a common session key, with the augmented reality room as described above to increase the security of data exchange with the augmented reality room, in particular with the second user  2 B also logged in to the same augmented reality room. 
     In an embodiment, after being permitted access to the augmented reality room, the communication device  1  of the first user  2  receives one or more of the following: a position, a bounding volume of all other users of the augmented reality room, a list of unoccupied positions in the augmented reality room, or common data of the augmented reality room. The position is a three dimensional position in the augmented reality room of the visual representations of other users, in particular the visual representation  54  of the second user  2 B. The bounding volume is a three dimensional volume encompassing the visual representation of the other users, in particular the three dimensional volume encompassing the visual representation  54  of the second user  2 B. The list of unoccupied positions comprises one or more positions in three-dimensional space in the augmented reality room, which positions are not occupied by any other user. Common data of the augmented reality room is data which has been provided by the augmented reality room to all participants of the augmented reality room, or data which has been provided by another user of the augmented reality room for all participants of the augmented reality room. 
     In an embodiment, the first user  2  occupies a particular position in the augmented reality room. More specifically, the visual representation of the first user  2  occupies the particular position in the augmented reality room, and the rendering system  11  of the communication device  1  is configured to render the augmented reality room using a visual perspective of the first user  2 . The communication device  1  of the first user  2  is configured to ensure that no other user, in particular visual representation of the other user, occupies the same space as the first user  2 . In particular, that the bounding volume of the other user does not overlap the bounding volume of the first user  1 . The communication device  1  is configured not to render the visual representation of the other user should such an overlap of bounding volumes occur. 
     In Step S 7 , the first user  2  transmits the first user data, in a transmission T 7 , to the augmented reality interaction server  5 . In Step S 71 , the augmented reality interaction server  5  receives the first user data and routes the first user data to the communication device  1 B of the second user  2 B in a transmission T 7 B. Additionally, the augmented reality interaction server  5  can route the first user data to additional users who are also located at in the virtual real estate object  41 , either physically or virtually. The communication device  1 B of the second user  2 B receives the first user data in step S 72 . The communication device  1 B transmits the second user data of the second user  2 B to the augmented reality interaction server  5  in a transmission T 8 B. In step S 74 , the augmented reality interaction server  5  then routes the second user data to the first user  2  in a transmission T 8 . 
     In step S 8 , the communication device  1  of the first user  2  receives the second user data. 
     In an embodiment, the second user data is processed using to content filters which are stored in the communication device  1 . Additionally, content filtering can also take place in the augmented reality interaction server  5 . In particular, the augmented reality interaction server  5  processes received data (i.e. first user data and/or second user data) using content filters, rejecting the received data and not transmitting the received data if it matches one of the filter criteria of the content filter. Content filtering in the augmented reality interaction server  5  ensures that only permitted content is routed via the augmented reality interaction server  5 . Content filtering in the communication device  1  ensures that only permitted content is stored in the communication device  1  and rendered and/or played back by the communication device  1 . 
     In an embodiment, the communication device  1  further processes the received second user data according to user settings. User settings include, for example, a language setting. For example, if audio data relating to speech data is contained in the second user data, the electronic circuit  13  of the communication device  1  processes the speech data according to language setting, automatically translating the speech data from a first language of the speech data into a second language according to the language setting, or generating text from the speech data of the audio data. 
     Therefore, users who are physically located at the virtual real estate object location  42  can interact (e.g. exchange data) with users virtually located at the virtual real estate object location  42  and vice versa. In particular, the location data  21  of the first user  2  corresponds to an emulated location or physical location and the first user  2  can therefore interact with the second user  2 B. 
       FIG.  9    shows a flow diagram illustrating an exemplary sequence of steps for augmented reality interaction. 
     In step S 9 , the communication device  1  of the first user  2 , in particular the one or more cameras  12 , capture one or more images of the first user  2 . The images are 2D or 3D still or video images of the first user  2  and are transmitted from the one or more cameras  12  to the electronic circuit  13  of the communication device  1 . In an embodiment, audio data of the first user  2  is recorded using the one or more microphones  15  and transmitted to the electronic circuit of the communication device  1 . 
     In step S 10 , the electronic circuit determines visual representation data of the first user  2  using the one or more images. The visual representation data is data which is used to render a visual representation of the first user  2 . The visual representation data is, in an embodiment, used to generate a life-like 2D or 3D rendering of the first user  2 . The visual representation data is, in an embodiment, used to generate an avatar of the first user  2 , the avatar being a graphical 2D or 3D representation of the user which is not intended to be lifelike. 
     Depending on the embodiment, the visual representation data comprises user motion data, relating to the movement of the first user  2 ; pose data, relating to the position of the body of the first user  2 , in particular the face; and/or facial expression data, for example comprising expressions, eye movements, or emotions of the first user  2 . 
     In Step S 11 , the communication device  1  transmits the visual representation data to the augmented reality interaction server  5  which, in step S 111 , routes the data to the communication device  1 B of the second user  2 B. The second user  2 B receives the visual representation data of the first user  2  in step S 112 . The communication device  1 B of the second user  2 B then renders the visual representation of the first user  2  using the visual representation data. In an embodiment, rendering the visual representation of the first user  2  uses a pre-stored model of the first user  2  stored in the communication device  1 B of the second user  2 B. 
     In an embodiment, the audio data of the first user  2  is transmitted to the augmented reality interaction server  5 . 
     In Step S 113 , the communication device  1 B of the second user  2 B captures one or more images of the second user  2 B and determines visual representation data of the second user  2 B. In step S 114 , the communication device  1 B of the second user  2 B transmits the visual representation data of the second user  2 B to the augmented reality interaction server  5  which routes the data, in step S 115 , to the communication device  1  of the first user  2 . The communication device  1  of the first user  2  receives the visual representation data of the second user  2 B in step S 12 . In step S 13 , the communication device  1  renders the visual representation  54  of the second user  2 B, using the visual representation data and the rendering system  11 . 
     In an embodiment, the communication device  1 B also records second user audio data which is transmitted to the augmented reality server  5  and routed, by the augmented reality server  5  to the communication device  1  of the first user  2 . The communication device  1  plays back the second user audio data using the one or more speakers  14 . Preferably, the speakers  14  play back the second user audio data as if emanating from the visual representation  54  of the second user  2 B, for improved realism. 
     As explained above in relation to  FIG.  8   , the communication device  1  can further process the received data, including the visual representation data and/or the second user audio data according to the user settings. 
     In an embodiment, rendering the visual representation  54  of the second user  2 B uses a pre-stored model of the second user  2 B stored in the communication device  1  in conjunction with the visual representation data, in particular the user motion data. Using the user motion data in conjunction with the visual representation data has the advantage that less data must be transmitted, because the user motion data is a compact representation only of the motion of the second user  2 B, and does not comprise other details of the visual appearance of the second user  2 B. 
     In an embodiment, the steps described above are carried out continuously such that the visual representation data is continuously streamed from the communication device  1  of the first user  2  to the communication device  2  of the second user  2 B, and vice versa. In an embodiment, the streaming occurs in real-time, such that a natural interaction in augmented reality between the first user  2  and the second user  2 B is achieved. In an embodiment, this is achieved by arranging the augmented reality interaction server  5  arranged at the virtual real estate object location  42 , such that the latency of transmission between the users and the augmented reality interaction server  5  is reduced. 
     In an embodiment, in addition to visual representation data being exchanged, audio data is also exchanged between the first user  2  and the second user  2 B via the augmented reality interaction server  5 . In particular, audio data recorded by the one or more microphones  15  is transmitted by the communication device  1  of the first user  1 , via the augmented reality interaction server  5  to the communication device  1 B of the second user  1 B. 
       FIG.  10    shows a flow diagram illustrating an exemplary sequence of steps for interacting with an augmented reality object. The sequence of steps enables the first user  2  and the second user  2 B to interact with an augmented reality object  53  common to both of them. In particular, the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B exchange data with the augmented reality interaction server  5  in a continuous manner such that the augmented reality object  53  is continually updated at both the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B. 
     In step S 14 , the augmented reality interaction server  5  transmits the augmented reality object  53  to the communication device  1  of the first user  2  and the communication device  2  of the second user  2 B. The augmented reality object  53  is a representation of an object which can be rendered in augmented reality, in particularly rendered by the communication device  1 . The augmented reality object  53  can encompass one or more sensory modalities, for example visual, haptic, and/or auditory modalities. The augmented reality object  53 , for example, comprises a 2D or 3D image (static images and/or moving images), a sound recording, and/or a scent, depending on the embodiment. The 2D image represents, for example, a graphic image, a photograph or a video clip. The 3D image represents, for example, a CAD object, a 3D model, or a topographical map. The augmented reality object  53  comprises, for example, a document, which document consists of text content and/or image content. 
     In step S 15  and step S 15 ′, the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B receive the augmented reality object  53 , respectively. 
     In an embodiment, in addition to the augmented reality object  53 , the identification information  43  of each particular virtual real estate object  41  to which the augmented reality object  53  is assigned is received with the augmented reality object  53 . The augmented reality object  53  received is then processed in the communication device  1  by associating the augmented reality object  53  with a specific virtual real estate object  41 , in particular by matching the identification information  43  of the specific virtual real estate object  41  as stored (received part of the query response as described above in relation to step S 3  of  FIG.  8   ) in the communication device  1  with the identification information  43  received. 
     In an embodiment, the communication device  1  processes the augmented reality object  53  using a set of content filters which are stored in the communication device  1 . The content filters are used to determine whether the augmented reality object  53 , is accepted or rejected. 
     In step S 16  and step S 16 ′, the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B render the augmented reality object  53 , respectively. In an embodiment, the hardware configuration of the communication device  1  may be used to determine which aspects of the augmented reality object  53  are rendered. In particular, whether the visual, haptic, and/or auditory aspects of the augmented reality object  53  are rendered depends on whether the hardware configuration indicates that the communication device  1  has hardware modules which can render or play back a given content type. 
     In an embodiment, different content types are encrypted using different encryption keys. In particular, the augmented reality room implemented in the augmented reality interaction server  5  generates a content session key for each content type and securely distributes the content session key to the communication device  1  of the first user  2  and to other participants of the augmented reality room (i.e. communication devices of other participants in the augmented reality room). The communication device  1  is configured to encrypt data transmitted to the augmented reality room using a content session key according to the content type of the data, and to decrypt data received from the augmented reality room using the content session key according to the content type of the data. 
     In an embodiment, the communication device  1  of the first user  2  renders the augmented reality object  53  according to the user settings, which determine, for example, the size and position of the augmented reality object  53 . Thereby the first user  2  can customize the appearance and/or functionality of the augmented reality object  53  according to their requirements, in particular the limitations of the communication device  1 , or the space in which the augmented reality content  51  is rendered. 
     The augmented reality object  53 , and more generally all augmented reality content  51 , is rendered such that the augmented reality object  53  is located (mapped and arranged) in the virtual real estate object  41 . For example, if the augmented reality object  53  comprises visual content, this visual content will appear on the rendering system  11  in the virtual real estate object  41  at the virtual real estate object location  42 . In particular, the visual content will be rendered inside the bounding volume V of the virtual real estate object  41 . Further, if the augmented reality object  53  comprises auditory content, the auditory content will be played back as if originating from a virtual audio source inside the virtual real estate object  41  at the virtual real estate object location  42 , more particularly at a virtual audio source at or inside the augmented reality object  53 . Further, the communication device  1  is configured such that only if the location information  21  of the first user  2  is inside the virtual real estate object  41  or its bounding volume V auditory content is played back to the first user  2  using the one or more speakers  14 . 
     In an embodiment where the communication device  1  is a smart phone, the electronic circuit  13  is configured to direct the one or more cameras  12  to capture an image of the real-world and to direct the rendering system  11  to display the image of the real-world. The electronic circuit  13  then renders the image (visual content) of the augmented reality object  53  on the rendering system  11 , such that both the real-world and the augmented reality object  53  are displayed simultaneously, with the visual content overlaid on the image of the real-world. 
     Depending on the embodiment, the augmented reality object  53  is rendered in step S 16  using a template augmented reality object stored in the communication device  1  of the first user  1 . The template augmented reality object is configured to provide for the communication device  1 , in particular the rendering system  11 , a framework for rendering the augmented reality object  53 . In an embodiment, the template augmented reality object is a member of a particular type of augmented reality object, and the communication device  1  is configured to identify a type of the augmented reality object  53  and render the augmented reality object  53  using the template augmented reality object assigned to that type of augmented reality object. The advantage of using template augmented reality objects is that less data must be transmitted from the augmented reality interaction servers  5  to the communication device  1  for the communication device  1  to render the augmented reality object  1 . 
     In step S 17 , the communication device  1  of the first user  2  determines user interaction data of the first user  2  with the augmented reality object  53 . In particular, user inputs of the first user  2  are recorded by the electronic circuit  13 . User inputs comprise user interface inputs, such as entered using a keyboard, gesture inputs registered using the motion tracker  16  and/or the one or more cameras  12  and voice inputs registered using the one or more speakers  14 . The user inputs relate to additions and/or modifications of the augmented reality object  53 , for example if the augmented reality object  53  represents a text document, the user inputs can relate to additions, deletions, or modifications of the text document. The user interaction data is transmitted by the communication device  1  to the augmented reality interaction server  5  in step S 18 . 
     In step S 181 , the augmented reality interaction server  5  receives the user interaction data. The augmented reality interaction server  5 , in an embodiment, also receives user interaction data from other users via their communication devices, in particular user interaction data from the communication device  1 B of the second user  2 B. In step S 182 , the augmented reality interaction server  5  determines an updated augmented reality object  53  using the user interaction data. In an embodiment, the augmented reality interaction server  5  determines object update data of the augmented reality object  53 . The object update data is configured such that the communication devices of those users which received the augmented reality object  53  are enabled to generate the updated augmented reality object  53 . Determining the object update data is advantageous as it relates not to the entire updated augmented reality object  53 , but merely to a difference between the augmented reality object  53  and the updated augmented reality object, which typically requires less data to store. 
     In step S 191 , the augmented reality interaction server  5  transmits the updated augmented reality object to the communication devices, in particular the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B. In an embodiment, instead of the updated augmented reality object, the object update data is transmitted. 
     In steps s 19  and S 19 ′ the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B receive the updated augmented reality object, respectively. In steps S 20  and S 20 ′, the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B render the updated augmented reality object, respectively. In the embodiment where the object update data was transmitted, the communication device  1  of the first user  2  and the communication device  1 B of the second user  2 B each receive the object update data and each render the updated augmented reality object using the augmented reality object  53  and the object update data. 
     The steps described above allow the first user  2  and the second user  2 B to both have rendered for them a copy of the same augmented reality object  53 . Any user inputs of either of these users with the augmented reality object  53  are registered as user interaction data which is used by the augmented reality interaction server  5  to determine an updated augmented reality object, or object update data thereof. The updated augmented reality object, or object update data relating to the augmented reality object  53 , is transmitted to the communication devices of both users. Very frequent updates of the augmented reality object  53  are achieved particularly by use of the object update data, which results in a fluid interaction in real time. This is because the object update data requires less data and therefore smaller data messages are required, reducing the requirements of bandwidth and also decreasing the time between updates. Thereby a coherent and fluid interaction between two users and an augmented reality object is made possible. 
       FIG.  11    shows a flow diagram illustrating an exemplary sequence of steps for processing augmented reality content  51  according to an embodiment of the invention. In step S 21 , the communication device  1  receives augmented reality content  51 , which comprises user data (i.e. second user data), representation data of the second user including visual representation data and auditory representation data, and augmented reality objects  53 . In step the electronic circuit  13  of the communication device  1  verifies whether the augmented reality content  51  fits inside the bounding volume V of the virtual real estate object. In particular, the electronic circuit  13  verifies that the visual content of the augmented reality content  51  does not extend beyond the bounding volume V. If the visual content, such as a 3D model or image, does not extend beyond the bounding volume V of the virtual real estate object  51 , then a positive verification is generated in the electronic circuit  13  and step S 23  is executed by the electronic circuit  13 . In step S 23 , the communication device renders the augmented reality content  51 , as described for example in step S 13  of  FIG.  9    and step S 16  of  FIG.  10   , which relate to the aspects of rendering the visual representation  54  of the second user  2 B and rendering the augmented reality object  53 , respectively. If the visual content does extend beyond the bounding volume V of the virtual real estate object  51 , then a negative verification is generated in the electronic circuit  13  and the electronic circuit proceeds to either step S 222  or S 232 , depending on a configuration of the communication device  1 . In step S 323 , the electronic circuit  13  does not render the augmented reality content  51 . In step S 222 , the augmented reality content  51  is modified such that it fits inside, i.e. does not extend beyond, the bounding volume V of the augmented reality content  51 . This modification of the augmented reality content  51  allows the communication device  1  to render the augmented reality content  51  in step S 231 , without the augmented reality content  51  extending beyond the virtual real estate object  41  and without extending into a neighboring virtual real estate object  41 . 
       FIG.  12    shows a block diagram illustrating modification of augmented reality content  51  according to an embodiment of the invention. The augmented reality content  51 , in particular the visual content of the augmented reality content  51 , for example the augmented reality object  53 , is resized, reshaped, truncated, and/or otherwise modified in step S 222 , to generated modified augmented reality content  52 , in particular a modified augmented reality object  55 , which fits inside the bounding volume of the virtual real estate object  41 . 
     It should be noted that, in the description, the sequence of the steps has been presented in a specific order, one skilled in the art will understand, however, that the order of at least some of the steps could be altered, without deviating from the scope of the invention.