Patent Publication Number: US-9420392-B2

Title: Method for operating a virtual reality system and virtual reality system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and hereby claims priority to German Application No. 10 2014 009 298.4 filed on Jun. 26, 2014, the contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The invention relates to a method for operating a virtual reality system and a virtual reality system. 
     A virtual reality system is a system by which a virtual reality can be displayed. The virtual reality system comprises in particular so-called virtual reality glasses, being a certain form of a so-called head-mounted display, i.e. a visual output device that can be worn on the head. It presents images on a display screen close to the eyes or projects them directly onto the retina. In this case a pair of virtual reality glasses additionally comprises sensors for motion detection of the head. This enables the display of the calculated graphics to be adapted to the movements of the wearer of the glasses. As a result of the physical proximity, the displayed image areas of the head-mounted display are effectively significantly larger than the free-standing display screens and in extreme cases even cover the entire field of view of the user. Because the display follows all head movements of the wearer as a result of the head mounting, the wearer has the sensation of moving directly in a landscape generated by a computer. 
     A virtual reality can thus be displayed by such virtual reality glasses, wherein the display of and at the same time the perception of reality in its physical characteristics in an interactive virtual environment generated by computer in real time are usually referred to as a virtual reality. 
     Such a virtual reality system can for example be used for the marketing of motor vehicles, in order to represent a motor vehicle virtually by the virtual reality glasses. In particular, in the case of such an application there is a challenge that the wearer of the virtual reality glasses is played very high quality sound by suitable headphones on the one hand and at the same time should be able to comprehend information from a salesperson and/or other associates and to follow their conversations. 
     The wearer of the virtual reality glasses can for example move around a virtual object, for example a motor vehicle, within a displayed virtual environment. A particular challenge in this connection is to play the spoken utterings of people in the surroundings of the wearer of the virtual reality glasses by said headphones so that the wearer of the virtual reality glasses is not confused. 
     SUMMARY 
     It is one possible object to provide a method for operating a virtual reality system and a virtual reality system that enables a wearer of virtual reality glasses to be provided especially with the spoken utterings of one or more people in an improved manner. 
     The inventors propose a method for operating a virtual reality system comprises the following:
         Detecting a spatial position of a head of a first person wearing virtual reality glasses and headphones;   Displaying at least one virtual object within a virtual environment from a virtual direction of view by the virtual reality glasses, wherein the virtual direction of view is specified depending on the detected spatial position of the head;   Reproducing an acoustic recording by the headphones;   Detecting speech sound from at least one second person by a microphone device and converting the detected speech sound into a speech signal;   Reproducing the speech signal by the headphones, wherein a left loudspeaker and a right loudspeaker of the headphones are operated depending on the detected spatial position of the head such that the speech signal is reproduced by the loudspeakers as the speech sound would pass to the first person without the headphones being worn (ears, ear canal).       

     On the one hand the proposed method enables a wearer of virtual reality glasses to receive a particularly realistic display of a virtual object within a virtual environment, because he can change his viewing angle to the displayed virtual object in a simple manner by varying the spatial position of his head. Preferably, it is also possible in this case that the wearer of the virtual reality glasses can move within the displayed virtual environment. In other words, this means that he can vary his virtual position within the virtual environment, so that the respective perspective of the virtual object can be varied. In addition, an acoustic recording is reproduced by the headphones, so that for example very high quality sounding sound is played, whereby the virtual reality experience can be further improved or heightened. 
     It is important for the method that the speech signal is reproduced by the headphones so that a left and a right loudspeaker of the headphones are operated depending on the detected spatial position of the head of the wearer of the virtual reality glasses such that the speech signal is reproduced by the loudspeakers as the speech sound would pass to the wearer of the virtual reality glasses without the headphones being worn. Thus if the wearer of the virtual reality glasses were to change his virtual position within the virtual environment, then the acoustically detectable position of the second person would not change for the wearer of the virtual reality glasses. 
     In other words, the headphones are operated such that regardless of the virtual positioning within the virtual environment, the same directional localization can always be ensured by the reproduction of the speech signal, and indeed as if the user were hearing the second person without wearing headphones. Besides the second person, who can for example be a salesperson, there can for example also be a third person present. The speech sound from the third person can also be detected and converted into a corresponding speech signal by the microphone device. The speech signal of the third person is also reproduced by the headphones such that a left and a right loudspeaker of the headphones are operated depending on the detected spatial position of the head of the wearer of the virtual reality glasses such that the speech signal of the third person is also reproduced by the loudspeakers as if the speech sound were to pass to the wearer of the virtual reality glasses without the headphones being worn. 
     The wearer of the virtual reality glasses thus always has a substantially fixed directional localization in relation to the vocal utterings of people in the surroundings of the wearer of the virtual reality glasses, so that he maintains a type of acoustic orientation and anchoring to reality, even if the virtual environment is displayed in a particularly realistic manner. 
     An advantageous embodiment provides that a transition time difference between the left and the right loudspeakers of the headphones is adjusted while reproducing the speech signal depending on the detected spatial position of the head of the first person. This enables the speech signal to be reproduced by the loudspeakers particularly realistically as if the speech sound were to pass to the first person without the headphones being worn. 
     A further advantageous embodiment provides that while reproducing the speech sound a level difference between the left and the right loudspeakers of the headphones is adjusted depending on the detected spatial position of the head of the first person. This also allows the speech signal from the loudspeakers to be particularly realistically reproduced as if the speech sound were to pass to the first person without the headphones being worn. 
     In another advantageous embodiment it is provided that the speech sound is recorded by a binaural recording method, especially by a binaural dummy head recording. In the simplest case, two microphones are used that face laterally away from each other and are separated from each other by a spacing of about 17 cm to 22 cm, preferably of 17.5 cm. Said spacing and the placement approximately represent the position of the ear canals of an average human. An isolating body that absorbs or even reflects the sound, such as for example a football or a metal plate, is placed between the microphones in order to approximately simulate a head. By said type of recording of the sound, a particularly natural audio impression with a particularly accurate directional localization can be produced by the headphones. This is because binaural recordings, which replace the natural ear signals inhibited by headphone reproduction, represent the best possibility of realistically reproducing a spatial hearing impression. 
     Preferably, the microphone device comprises an artificial head fitted with a binaural recording device that is positioned between the first person and the second person, especially on a connecting line between the first and the second persons, wherein the speech sound is recorded by the binaural recording device. The artificial head is a head simulation, wherein the recording device for example comprises two capacitor studio microphones with omnidirectional characteristics inserted in an artificial ear canal of the artificial head. This arrangement simulates so-called head-related transmission functions, also known by the term head-related transfer functions. 
     In another advantageous embodiment, it is provided that the relative location and/or the position of the artificial head to the head of the first person, especially also to the head of the second person, is detected and taken into account during the reproduction of the speech signal. The corresponding location and position information are preferably used to control the reproduction of the speech signal such that a particularly realistic and spatial hearing impression is reproduced by the reproduction using the headphones, so that a particularly accurate directional localization is possible for the first person. 
     According to an alternative advantageous embodiment, it is provided that the microphone device comprises a microphone worn by the other person, by which the speech sound is recorded. Because the microphone device is worn by the other person, the speech sound of the other person is mainly recorded, wherein other ambient noise is recorded less strongly by the microphone device. 
     In another advantageous embodiment, it is provided that the relative location and/or position of the head of the second person to the head of the first person is recorded and taken into account during the reproduction of the speech signal. In other words, the relative positioning of the two people to each other and the respective orientation of the heads of the two people to each other are thus taken into account, so that the speech signal can be output such that a particularly good spatial hearing impression can be realistically achieved for the second person by playing back by the headphones. 
     According to another advantageous embodiment, it is provided that other ambient noise is recorded by the microphone device, wherein said ambient noise is filtered out and not reproduced by the headphones if said ambient noise is lower by a predefined volume level than the recorded speech sound of the second person. Therefore, in particular conversations from a certain distance can effectively be blocked and not transferred via the headphones, which is especially helpful in a semi-public situation in a sales room. 
     In another advantageous embodiment, it is provided that further ambient noise is recorded by the microphone device, wherein said ambient noise, with the exception of the speech sound of the second person, is attenuated by active noise compensation generated by the headphones. In other words, a type of antisound is thus produced, by which the remaining ambient noise apart from the speech sound of the second person is attenuated or eliminated. 
     The virtual reality system comprises
         virtual reality glasses that are designed to display at least one virtual object within a virtual environment;   a detecting device that is designed to detect a spatial position of a head of a first person wearing the virtual reality glasses;   a control device that is designed to determine a virtual direction of view depending on the detected spatial position of the head of the first person and to control the virtual reality glasses such that they display the virtual object within the virtual environment from the virtual direction of view;   a microphone device that is designed to detect a speech sound of at least one second person and to convert it into a speech signal;   headphones with a left and a right loudspeaker that are designed to reproduce an acoustic recording and the speech signal;   wherein the control device is designed to control the headphones such that the left and the right loudspeakers of the headphones are operated depending on the detected spatial position of the head such that the speech signal is reproduced by the loudspeakers as if the speech sound were to pass to the first person without the headphones being worn.       

     The advantageous embodiments of the method are to be viewed here as advantageous embodiments of the virtual reality system, wherein the virtual reality system carries out the method. 
     Further advantages, features and details are revealed in the following description of preferred exemplary embodiments and using the figures. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and/or shown in the figures alone cannot only be used in the respectively specified combination but also in other combinations or on their own without departing from the scope. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and advantages of the present invention will become more apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  shows a schematic illustration of a virtual reality system for the display of a virtual object within a virtual environment; 
         FIG. 2  shows a perspective view of a partially illustrated sales room, wherein a person is wearing virtual reality glasses of the virtual reality system; 
         FIG. 3  shows an illustration of a virtual environment in which a virtual object in the form of a motor vehicle is displayed in a side view; 
         FIG. 4  shows a schematic top view of a possible embodiment of the sales room illustrated in  FIG. 2 , wherein besides the person wearing the virtual reality glasses another person and an artificial head disposed between them are illustrated; and 
         FIG. 5  shows a schematic top view of an alternative embodiment of the sales room, wherein again the wearer of the virtual reality glasses and here only the person opposite are illustrated, wherein said person opposite is wearing microphone. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     In the figures, identical or functionally equivalent elements are provided with the same reference characters. 
     A virtual reality system  10  for displaying a virtual environment is shown in a schematic illustration in  FIG. 1 . The virtual reality system  10  comprises virtual reality glasses that are designed to display at least one virtual object within a virtual environment. The virtual reality glasses  12  comprise in this case a detecting device  14  that is designed to detect a spatial position of a head of a person wearing the virtual reality glasses  12 . 
     Moreover, the virtual reality system  10  comprises a control device  16  that is designed to determine a virtual direction of view depending on the detected spatial position of the head of the wearer of the virtual reality glasses  12  and to control the virtual reality glasses  12  such that they display the currently displayed virtual object within the virtual environment from the virtual direction of view. 
     Moreover, the virtual reality system  10  comprises a microphone device  18  that is designed to detect speech sound from at least one second person and to convert it into a speech signal. Finally, the virtual reality system  10  comprises headphones  20  with a left and a right loudspeaker  22 ,  24  designed to reproduce an acoustic recording and the speech signal. In this case the control device  16  is designed to control the headphones  20  such that the left and the right loudspeakers  22 ,  24  of the headphones  20  are operated depending on the detected spatial position of the head of the wearer of the virtual reality glasses  12  such that the speech signal is reproduced by the loudspeakers  22 ,  24  as if the speech sound of the other person were to pass to the wearer of the virtual reality glasses  12  without the headphones  20  being worn. 
     An unspecified sales room in a car dealership is shown in  FIG. 2 . In the present case a first person  26  is wearing the virtual reality glasses  12  of the virtual reality system  10 . The virtual reality glasses  12  are coupled in the present case to the control device  16  disposed under a table  28 , wherein the control device can be a conventional PC for example. Furthermore, the virtual reality system  10  comprises a remote controller  30 , by which the user  26  can control the display of the virtual reality glasses  12 . A coordinate system that is fixed relative to the head of the first person  26  is denoted by the axes x 1 , y 1  and z 1 . 
     In  FIG. 3  a virtual environment  32  is shown, wherein a virtual object in the form of a motor vehicle  34  is displayed within said virtual environment  32 . The current virtual position of the first person  26  within the virtual environment  32  is characterized with the dashed circle  36 . The current virtual direction of view, starting from the virtual position  36 , is characterized by the arrow  38 . The virtual direction of view  38  corresponds here to the current spatial position, i.e. the orientation, of the first person  26  that is wearing the virtual reality glasses  12 . If the wearer swivels his head for example to the left, then he is no longer looking, as shown here, at the motor vehicle  34 , but rather at a region further to the left within the virtual environment  32 . The same also applies to an upward and downward pivoting movement of the head of the person  26 . Furthermore, the person  26  can move within the virtual environment  32 , for example by suitable operation of the remote controller  30 , i.e. can for example virtually move around the vehicle  34 . The coordinate system within the virtual environment  32  is denoted by the axes x 2 , y 2  and z 2 . 
     In addition to a purely visual illustration of the virtual environment  32 , a recording backing the virtual illustration is played by the headphones  20 . For example, the recording can be purely music or even suitable operating sound of the virtual motor vehicle  34 , such as for example exhaust noise, sound from the stereo system of the motor vehicle  34  and similar. In this case, said virtual noises can for example also be changed depending on the virtual position of the person  26  within the virtual environment  32 , so that a type of virtual spatial hearing impression can be enabled within the displayed virtual environment  32  by playing back by the headphones  20 . 
     In  FIG. 4  a possible arrangement of the first person  26  relative to a second person  40 , for example a salesperson in a car dealership, is shown in a schematic top view. An artificial head  42  is disposed between the first person  26  and the second person  40  on the table  28  of the sales room. In the present case the microphone device  18  is formed by respective unspecified microphones disposed on the outside of the artificial head  42 . Speech sound  44  emitted by the second person  40  is detected by the microphone device  18 . In the present case the speech sound  44  is thus detected by a binaural recording method, more accurately by a binaural dummy head recording. The relative location and/or position of the artificial head  42  to the head  25  of the first person  26  and also to the head  46  of the second person  40  is detected in this case and is taken into account during the reproduction of the speech signal by the headphones  20 . 
     The speech signal is reproduced here by the headphones  20 , wherein the left and the right loudspeakers  22 ,  24  of the headphones  20  are operated depending on the detected spatial position of the head  25  of the first person  26  and the additional detected positions and location information of the head  25  relative to the artificial head  42  and of the head  46  of the second person  40  such that the speech signal is reproduced by the loudspeakers  22 ,  24  as if the speech sound were to pass to the first person without the headphones  20  being worn, more accurately to his ears or into his ear canals. For example, when reproducing the speech signal a transition time difference and/or level difference between the left and right loudspeakers  22 ,  24  of the headphones  20  is adjusted depending on the spatial location and position information. 
     A coordinate system that is fixed relative to the head of the second person  40  is denoted by the axes x 3 , y 3  and z 3 . A coordinate system that is fixed relative to the artificial head  42  is denoted by the axes x 4 , y 4  and z 4 . The respective relative locations relative to the fixed coordinate systems of the head  46  of the second person, of the artificial head  42  and of the head  25  of the first person  26  can thus be detected and analyzed in relation to their locations and positioning relative to each other. Moreover, the volume setting with which the speech signal converted from the detected speech sound  44  by the headphones  20  is fed through the headphones  20  is adjusted taking into account the respective spacings A 1 , A 2  and A 3  between the respective heads  25 ,  42 ,  46 . 
     Thus if the first person  26  is moving around within the virtual environment  32  by the displayed contents of the virtual reality glasses  12 , the detected speech sound  44  is always played through the headphones  20  by the converted speech signal such that the perceived position of the second person  40  relative to the first person  26  does not change. In other words, the directional localization for the first person  26 , who is wearing the virtual reality glasses  12 , always remains constant relative to the second person  40 , at least while the second person  40  is not moving. 
     Further ambient noise can for example also be detected by the microphone device  18 , wherein said ambient noise is filtered out and is not reproduced by the headphones  20  if said ambient noise is lower by a predefined volume level than the detected speech sound of the second person  40 . This enables speech from a defined distance to be effectively blocked and not transferred to the first person  26  by the headphones  20 , which is especially useful in the case of a semi-public situation in a car dealership. 
     Alternatively or additionally, it is also possible for the headphones  20  to be so-called active noise cancelling headphones. Either the headphones  20  themselves comprise suitable microphones for detecting the ambient sound or the sound information acquired by the microphone device  18 , with the exception of the speech sound  44  of the second person  40 , is attenuated by active noise compensation produced by the headphones  20 , i.e. by antisound. This also allows it to be ensured that above all only the speech sound  44  passes to the ears of the first person  26 . 
     An alternative arrangement between the first and the second persons is illustrated in  FIG. 5 . In the present case the artificial head  42  is no longer located between the first and the second persons  26 ,  40 . Instead of this the second person  40  is wearing a microphone  48  belonging to the microphone device  18  immediately in front of his mouth, by which the speech sound  44  is detected. This has the advantage that ambient noise is hardly detected or is detected significantly less strongly than with the arrangement shown in  FIG. 4 . Here too the relative location and/or position of the head  46  of the second person  40  to the head  25  the first person  26  is detected and is taken into account during the reproduction of the converted speech signal. The speech signal is in turn reproduced by the headphones  20 , wherein the left and right loudspeakers  22 ,  24  of the headphones  20  are operated depending on the detected location and position information such that the speech signal is reproduced by the loudspeakers  22 ,  24  as if the speech sound  44  were to pass to the first person  26  without the headphones  20  being worn. Here for example the transition time difference and/or even the level difference between the left and the right loudspeakers  22 ,  24  can be suitably adjusted in order to enable a most realistic reproduction of the detected speech sound  44  and an associated particularly accurate and realistic directional localization of the speech sound  44  and hence of the second person  40 . In this connection it is possible to carry out active noise compensation in a similar manner in order to attenuate or block further ambient noise as far as possible. Or just as good, detected ambient noise can also be filtered out and not reproduced by the headphones  20 , if it were to be lower by a predefined volume level than the detected speech sound  44  of the second person  40 . The latter should be particularly simple to design because the microphone  48  is worn immediately in front of the mouth of the second person  40 , so that the speech sound  44  emitted by the second person  40  should arrive significantly louder at the microphone  48  than the rest of the ambient noise. 
     The invention has been described in detail with particular reference to preferred embodiments thereof and examples, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention covered by the claims which may include the phrase “at least one of A, B and C” as an alternative expression that means one or more of A, B and C may be used, contrary to the holding in  Superguide v. DIRECTV,  69 USPQ2d 1865 (Fed. Cir. 2004).