Patent Publication Number: US-2023161537-A1

Title: Information display system, information display method, and processing device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. Provisional Application Serial no. 63/278,071, filed on Nov. 10, 2021, and Taiwan application serial no. 111130006, filed on Aug. 10, 2022. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     Technical Field 
     The disclosure relates to an information display system, an information display method, and a processing device. 
     Description of Related Art 
     With the development of image processing technology and spatial positioning technology, applications of a transparent display has gradually received attention. Such technology, combined with physical objects and aided with virtual objects, allows the display to generate an interactive experience depending on needs of a user, and present information in a relatively intuitive way. 
     Furthermore, a virtual object associated with a physical object may be displayed on specific positions of the transparent display, so that the user can see the physical object and the virtual object superimposed on, or at one side of, the physical object through the transparent display at the same time. For example, with the transparent display disposed on an observation deck, a viewer can see the landscape and landscape information provided by the transparent display at the same time. However, in some large-scale application scenarios, a combination of multiple transparent displays may be required to provide information display services of merged virtuality and reality, and there may also be a greater number of physical objects and users. Therefore, if a single central computing device is configured to be in charge of all computing tasks, computational delays may occur because of excessive computing load or other factors, resulting in failure to provide the viewer with real-time display services of merged virtuality and reality. 
     SUMMARY 
     In an exemplary embodiment of the disclosure, an information display system includes a plurality of light-transmissive displays, a plurality of perception information capture devices, and a plurality of processing devices. The plurality of perception information capture devices are configured to capture position information and posture information of a user and capture position information of a target. The plurality of processing devices respectively correspond to the displays, and are connected to and communicate with each other through a plurality of gateways. A first processing device is selected from the processing devices according to the position information of the user. The first processing device determines sight line information of the user according to the position information and the posture information of the user provided by the perception information capture devices. A second processing device different from the first processing device performs coordinate conversion and calculates a target coordinate of the target according to the position information of the target provided by the perception information capture devices. The first processing device selects a third processing device from the processing devices according to the sight line information of the user. The third processing device determines display position information of a virtual object according to a user coordinate and the target coordinate. The third processing device controls one of the displays to display the virtual object according to the display position information of the virtual object. 
     In an exemplary embodiment of the disclosure, an information display method is adapted for an information display system including a plurality of light-transmissive displays, a plurality of perception information capture devices, and a plurality of processing devices. The information display method includes the following. The perception information capture devices are configured to capture position information and posture information of a user and position information of a target. A first processing device is selected from the processing devices according to the position information of the user. Sight line information of the user is determined by the first processing device according to the position information and the posture information of the user provided by the perception information capture devices. Coordinate conversion is performed and a target coordinate of the target is calculated by a second processing device different from the first processing device according to the position information of the target provided by the perception information capture devices. A third processing device is selected from the processing devices according to the sight line information of the user. By the third processing device, display position information of a virtual object is determined according to a user coordinate and the target coordinate, and one of the displays is controlled to display the virtual object according to the display position information of the virtual object. 
     In an exemplary embodiment of the disclosure, a processing device is connected to a light-transmissive display and a perception information capture device, and is connected to a plurality of other processing devices through a plurality of gateways. The perception information capture device is configured to capture position information and posture information of a user and capture position information of a target. The processing device includes a memory and a processor. The memory is configured to store data. The processor is connected to the memory and is configured to: determine, by the perception information capture device, that a distance between the processing device and the user is less than a distance between each of the plurality of other processing devices and the user; determine sight line information of the user according to the position information and the posture information of the user provided by the perception information capture device; and select one of the plurality of processing devices according to the sight line information of the user, and transmit the sight line information of the user to the one of the plurality of processing devices through the gateways. The one of the plurality of processing devices determines display position information of a virtual object according to the sight line information, a user coordinate, and a target coordinate, and controls the display or another display connected to the other processing devices to display the virtual object according to the display position information of the virtual object. 
     Several exemplary embodiments accompanied with figures are described in detail below to further describe the disclosure in details. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments and, together with the description, serve to explain the principles of the disclosure. 
         FIG.  1 A  is a block diagram of an information display system according to an exemplary embodiment of the disclosure. 
         FIG.  1 B  is a schematic diagram of an information display system according to an exemplary embodiment of the disclosure. 
         FIG.  2    is a flowchart of an information display method according to an exemplary embodiment of the disclosure. 
         FIG.  3 A  is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure. 
         FIG.  3 B  is a flowchart of an information display method according to an exemplary embodiment of the disclosure. 
         FIG.  4 A  is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure. 
         FIG.  4 B  is a flowchart of an information display method according to an exemplary embodiment of the disclosure. 
         FIG.  5 A  and  FIG.  5 B  are schematic diagrams of estimating a sight line position according to an exemplary embodiment of the disclosure. 
         FIG.  6 A  is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure. 
         FIG.  6 B  is a flowchart of an information display method according to an exemplary embodiment of the disclosure. 
         FIG.  7    is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure. 
         FIG.  8 A  is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure. 
         FIG.  8 B  is a flowchart of an information display method according to an exemplary embodiment of the disclosure. 
         FIG.  9    is a block diagram of a processing device according to an exemplary embodiment of the disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Some exemplary embodiments of the disclosure with the accompanying drawings will be described in detail. For the reference numerals used in the following description, the same reference numerals shown in different drawings will be regarded as the same or similar elements. These exemplary embodiments are only a part of the disclosure and do not disclose all possible implementations of the disclosure. More specifically, these exemplary embodiments are merely examples of the method and the system within the scope of the disclosure. 
       FIG.  1 A  is a block diagram of an information display system according to an exemplary embodiment of the disclosure.  FIG.  1 A  first introduces members in the system and their configuration relationships, and detailed functions thereof will be disclosed together with the flowcharts of the subsequent exemplary embodiments. 
     With reference to  FIG.  1 A , an information display system 10 in this exemplary embodiment may include a plurality of displays  110 _ 1 ,  110 _ 2 ,  110 _ 3 , ..., and  110 _N, a plurality of perception information capture devices  120 _ 1 ,  120 _ 2 ,  120 _ 3 , ..., and  120 _N, and a plurality of processing devices  130 _ 1 ,  130 _ 2 ,  130 _ 3 , ..., and  130 _N. The processing devices  130 _ 1  to  130 _N may be wirelessly, wiredly, or electrically connected to respectively the displays  110 _ 1  to  110 _N and the perception information capture devices  120 _ 1  to  120 _N. Note that, to serve as an example for description in the exemplary embodiment of  FIG.  1 A , one processing device is connected to one display and one perception information capture device, for example, the processing device  130 _ 1  is connected to the display  110 _ 1  and the perception information capture device  120 _ 1 , but the disclosure is not limited thereto. In other examples, one processing device may be connected to a plurality of perception information capture devices or a plurality of displays. 
     The displays  110 _ 1  to  110 _N may be configured to display information, and may include one display device or a combination of a plurality of display devices. For example, the display device may be a liquid crystal display (LCD), a field sequential color LCD, a light-emitting diode (LED) display, and an electrowetting display among other light-transmissive displays of a transmission mode, or may be a light-transmissive display of a projection mode. 
     The perception information capture devices  120 _ 1  to  120 _N may be configured to capture position information and posture information of a user. The perception information capture devices  120 _ 1  to  120 _N include a sensing device for capturing information of the user. In some embodiments, the perception information capture devices  120 _ 1  to  120 _N may include at least one image sensor or may include at least one image sensor combined with at least one depth sensor to capture image data toward a user located in front of the displays  110 _ 1  to  110 _N, so as to perform image identification and positioning on the user. The image sensor may be a visible light sensor or a non-visible light sensor, such as an infrared sensor. In addition, the perception information capture devices  120 _ 1  to  120 _N may also include an optical localizer to perform optical spatial localization on the user. In some embodiments, the perception information capture devices  120 _ 1  to  120 _N may also identify postures presented by the limbs, torso, and head of the user through various human posture identification technologies. For example, the perception information capture devices  120 _ 1  to  120 _N may identify feature points on the human skeleton and the human body according to the image data, so as to identify the posture of the user. For any devices or a combination thereof, that can locate the position information of the user and identify the posture information of the user, they all fall within the scope of the perception information capture devices  120 _ 1  to  120 _N. 
     In addition, the perception information capture devices  120 _ 1  to  120 _N may be configured to capture position information of a target in a physical scene. The perception information capture devices  120 _ 1  to  120 _N include a sensing device for capturing information of the target. In some embodiments, the perception information capture devices  120 _ 1  to  120 _N may include at least one image sensor or may include at least one image sensor combined with at least one depth sensor to capture image data toward a target located behind the displays  110 _ 1  to  110 _N, so as to perform image identification and positioning on the target. The image sensor may be a visible light sensor or a non-visible light sensor, such as an infrared sensor. For any devices or a combination thereof, that can locate the position information of the target, they all fall within the scope of the perception information capture devices  120 _ 1  to  120 _N. 
     In the embodiments of the disclosure, the image sensor may be configured to capture an image and includes a camera lens having a lens element and a photosensitive element. The depth sensor may be configured to detect depth information, and may be realized by active depth sensing technology and passive depth sensing technology. The active depth sensing technology may calculate depth information by actively emitting a light source, infrared, ultrasonic, laser, and so on to serve as a signal combined with time difference ranging technology. The passive depth sensing technology may calculate depth information by utilizing the parallax of two images captured from different viewing angles by two image sensors behind the images. 
     In some embodiments, the perception information capture devices  120 _ 1  to  120 _N may transmit information to the processing devices  130 _ 1  to  130 _N through respective communication interfaces by wire or wirelessly. The processing devices  130 _ 1  to  130 _N are computer devices with computing function. The processing devices  130 _ 1  to  130 _N may each include a processor. For example, the processor may be a central processing unit (CPU), an application processor (AP), or any other programmable general-purpose or special-purpose microprocessor, a digital signal processor (DSP), an image signal processor (ISP), a graphics processing unit (GPU), or other similar devices, integrated circuits, or a combination thereof. The processing devices  130 _ 1  to  130 _N may be deployed in the field to which the information display system 10 belongs, and may be computer devices respectively built into the displays  110 _ 1  to  110 _N or connected to the displays  110 _ 1  to  110 _N. The processing devices  130 _ 1  to  130 _N respectively correspond to the displays  110 _ 1  to  110 _N, and may be configured to control the displays  110 _ 1  to  110 _N connected thereto. For example, the processing device  130 _ 1  may be configured to control the display  110 _ 1  to display contents. 
     For example,  FIG.  1 B  is a schematic diagram of an information display system according to an exemplary embodiment of the disclosure. For convenience and clarity in description, three displays  110 _ 1  to  110 _ 3  and three perception information capture devices  120 _ 1  to  120 _ 3  are shown in  FIG.  1 B  as an example for description, but the disclosure is not limited thereto. With reference to  FIG.  1 B , a user U1 and a target Obj1 are respectively located at the front side and the back side of the displays  110 _ 1  to  110 _ 3 . In this exemplary embodiment, the user U1 may view a physical scene of a virtual object Vf1 including the target Obj1 through the display  110 _ 2 . The virtual object Vf1 may be regarded as augmented reality content augmented based on the target Obj1. 
     Note that the processing devices  130 _ 1  to  130 _N are connected to and communicate with each other through a plurality of gateways G1, G2, ..., and Gk. Each of the gateways G1 to Gk supports wireless transmission protocols or wired transmission protocols, and may establish links with nearby gateways or the processing devices  130 _ 1  to  130 _N. The types of wireless transmission protocols and wired transmission protocols are not limited by the disclosure, and may be WiFi standards, ZigBee standards, mobile communication standards, Ethernet standards, or the like. In some embodiments, the gateways G1 to Gk may form a network topology N1. However, the disclosure does not limit the number of the gateways G1 to Gk and the form of the network topology. Each of the processing devices  130 _ 1  to  130 _N may be connected to at least one of the gateways G1 to Gk. With the links between the gateways G1 to Gk, the processing devices  130 _ 1  to  130 _N may transmit information and communicate with each other through the gateways G1 to Gk. 
     Note that, by configuring the links between the processing devices  130 _ 1  to  130 _N and the gateways G1 to Gk, the computing tasks required for displaying the virtual object Vf1 based on position information and posture information of the user U1 and position information of the target Obj1 may be distributed to and performed by some of the processing devices  130 _ 1  to  130 _N. Accordingly, computational efficiency may be improved through a distributed processing architecture to prevent delay in displaying the virtual object. 
       FIG.  2    is a flowchart of an information display method according to an exemplary embodiment of the disclosure. With reference to  FIG.  1 A ,  FIG.  1 B , and  FIG.  2    together, flows of the method of  FIG.  2    may be realized by the information display system 10 of  FIG.  1 A  and  FIG.   1 B . 
     In step S 210 , the perception information capture devices  120 _ 1  to  120 _N are configured to capture the position information and the posture information of the user U1 and the position information of the target Obj 1. As mentioned above, the perception information capture devices  120 _ 1  to  120 _N are, for example, image sensors, depth sensors, or a combination thereof that can locate the positions of the user U1 and the target Obj 1. 
     In step S 220 , a first processing device is selected from the processing devices  130 _ 1  to  130 _N according to the position information of the user U1. In some embodiments, the first processing device is closest in distance to the position information of the user U1 among the processing devices  130 _ 1  to  130 _N. In other words, a distance between the first processing device and the user U1 is less than a distance between each of the other processing devices and the user U1. At least one of the perception information capture devices  120 _ 1  to  120 _N may locate the position information of the user U1. Moreover, in the case where the processing devices  130 _ 1  to  130 _N have been fixedly disposed in the field to which the information display system 10 belongs, position information of the processing devices  130 _ 1  to  130 _N is known. Therefore, at least one of the processing devices  130 _ 1  to  130 _N may obtain the distance between each of the processing devices  130 _ 1  to  130 _N and the user U1 according to the position information of the user U1 and the known position information of each of the processing devices  130 _ 1  to  130 _N. Accordingly, the first processing device that is closest in distance to the position information of the user U1 among the plurality of processing devices may be selected. As can be known, the first processing device that is closest in distance to the user U1 may correspondingly change in response to dynamic movement of the user U1. 
     In step S 230 , sight line information E1 of the user is determined by the first processing device according to the position information and the posture information of the user U1 provided by the perception information capture devices  120 _ 1  to  120 _N. After the first processing device is selected, the first processing device may obtain the position information and the posture information of the user directly from one of the perception information capture devices  120 _ 1  to  120 _N connected thereto, or may obtain the position information and the posture information of the user from the gateways G1 to Gk. Therefore, the first processing device may identify the sight line information E1 according to the position information and the posture information of the user U1. The sight line information E1 includes a sight line vector. 
     In step S 240 , by a second processing device different from the first processing device, coordinate conversion is performed and a target coordinate of the target Obj1 is calculated according to the position information of the target Obj1 provided by the perception information capture devices  120 _ 1  to  120 _N. In other words, the second processing device performs coordinate conversion on the position information (e.g., camera coordinates or image coordinates) of the target Obj1 provided by at least one of the perception information capture devices  120 _ 1  to  120 _N, and obtains the target coordinate in a three-dimensional display coordinate system. 
     In step S 250 , a third processing device is selected from the processing devices  130 _ 1  to  130 _N by the first processing device according to the sight line information E1 of the user U1. After the first processing device obtains the sight line information E1 of the user U1, the first processing device identifies one of the displays  110 _ 1  to  110 _N according to the sight line information E1 of the user U1 to select the corresponding third processing device from the processing devices  130 _ 1  to  130 _N according to one of the displays  110 _ 1  to  110 _N. In some embodiments, the first processing device may calculate a viewing angle range corresponding to one of the displays  110 _ 1  to  110 _N according to the position information of the user U1. The first processing device identifies the one of the displays  110 _ 1  to  110 _N from the displays  110 _ 1  to  110 _ 3  in response to the sight line information of the user U1 falling within the viewing angle range. Taking  FIG.  1 B  as an example, the first processing device may calculate a viewing angle range corresponding to the display  110 _ 2  according to the position information of the user U1. Since the sight line information of the user U1 falls within the viewing angle range of the display  110 _ 2 , it may be determined that the sight line position of the user U1 falls on the display  110 _ 2 . 
     In other words, the first processing device may identify the display looked at by the user according to the sight line information E1 of the user U1. Since the displays  110 _ 1  to  110 _N may be respectively controlled by the corresponding processing devices  130 _ 1  to  130 _N, the first processing device may select the processing device corresponding to the display looked at by the user as the third processing device. Note that the first processing device may be the same as or different from the third processing device. In the scenario where the displays  110 _ 1  to  110 _N are arranged in parallel and the processing devices  130 _ 1  to  130 _N are respectively disposed adjacent to the corresponding displays  110 _ 1  to  110 _N, the first processing device closest in distance to the user U1 is the same as the third processing device looked at by the user U1 when the user looks at the display directly in front of the user; and the first processing device closest in distance to the user U1 is different from the third processing device looked at by the user U1 when the user looks at the displays at the left and right sides. 
     In some embodiments, the third processing device performs coordinate conversion and calculates a user coordinate of the user according to the position information of the user U1 provided by the perception information capture devices  120 _ 1  to  120 _N. In other words, the third processing device performs coordinate conversion on the position information (e.g., camera coordinates or image coordinates) of the user U1 provided by at least one of the perception information capture devices  120 _ 1  to  120 _N, and obtains the user coordinate in a three-dimensional display coordinate system. 
     In step S 260 , by the third processing device, display position information of the virtual object Vf1 is determined according to the user coordinate and the target coordinate, and one of the displays  110 _ 1  to  110 _N is controlled to display the virtual object Vf1 according to the display position information of the virtual object Vf1. In some embodiments, the second processing device may transmit the target coordinate of the target Obj 1 to the third processing device through the gateways G1 to Gk. Similarly, if the first processing device is different from the third processing device, the first processing device may also transmit the sight line information E1 of the user U1 to the third processing device through the gateways G1 to Gk. Based on this, the third processing device may determine the display position information of the virtual object Vf1 according to the user coordinate, the sight line information E1, and the target coordinate. The display position information may be regarded as a landing point or region where the sight line of the user is pointed on the display plane when the user views the target Obj1. Depending on various requirements or different applications, the third processing device may determine the actual display position of the virtual object Vf1 according to the display position information for the user U1 to see the virtual object Vf1 displayed near the target Obj1 or see the virtual object Vf1 displayed to be superimposed on the target Obj1. 
     As can be known accordingly, in the embodiment of the disclosure, by linking the gateways G1 to Gk with the processing devices  130 _ 1  to  130 _N, the amount of computation required for displaying the virtual object Vf1 may be allocated to be in the charge of a plurality of processing devices to improve computational efficiency and prevent delay in displaying the virtual object. 
     Embodiments accompanied with the display system 10 will be provided below to describe the implementations of the disclosure to determine the third processing device according to the sight line information of a single user and multiple users. For convenience and clarity in description in the following embodiments, three processing devices  130 _ 1  to  130 _ 3  respectively connected to three displays  110 _ 1  to  110 _ 3  and three perception information capture devices  120 _ 1  to  120 _ 3  will be taken as an example, but the disclosure is not limited thereto. The processing devices  130 _ 1  to  130 _ 3  may be respectively disposed adjacent to the corresponding displays  110 _ 1  to  110 _ 3 . 
       FIG.  3 A  is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure.  FIG.  3 B  is a flowchart of an information display method according to an exemplary embodiment of the disclosure. With reference to  FIG.  3 A  and  FIG.  3 B  together, in this embodiment, the user U1 is in front of the display  110 _ 2  and looks at the display  110 _ 2  directly in front of the user U1. 
     The perception information capture device  120 _ 2  may capture position information and posture information of the user U1 (step S 302 ), and transmit the position information and the posture information of the user U1 to the processing device  130 _ 2 , for example. In response to receiving the position information of the user U1, the processing device  130 _ 2  may calculate a distance between each of the processing devices  130 _ 1  to  130 _ 3  and the position information of the user U1. Moreover, the processing device  130 _ 2  may select a first processing device according to the distance between each of the processing devices  130 _ 1  to  130 _ 3  and the position information of the user U1 (step S 304 ). Here, the first processing device is closest in distance to the position information of the user U1 among the processing devices  130 _ 1  to  130 _ 3 . In this exemplary embodiment, it is assumed that the processing device  130 _ 2  is the first processing device closest in distance to the user U1. In other words, in an embodiment, by the perception information capture device  120 _ 2 , the processing device  130 _ 2  may determine that the distance between the processing device  130 _ 2  and the user U1 is less than the distance between each of the other processing devices  130 _ 1  and  130 _ 3  and the user U1. 
     Next, the processing device  130 _ 2  may identify the sight line information E1 of the user U1 according to the position information and the posture information of the user U1 (step S 306 ). The processing device  130 _ 2  is selected to calculate the sight line information E1 of the user U1 and determine on which display the sight line information E1 of the user U1 falls. In this exemplary embodiment, the processing device  130 _ 2  may determine that the sight line information E1 of the user U1 falls on the display  110 _ 2  according to the sight line information E1 of the user U1 and select a third processing device according to the display  110 _ 2  to which the sight line information E1 is pointed (step S 308 ). In this exemplary embodiment, the processing device  130 _ 2  for controlling the display  110 _ 2  is the third processing device. In other words, the first processing device and the third processing device in this exemplary embodiment are the same and both are the processing device  130 _ 2 . Therefore, the processing device  130 _ 2  performs coordinate conversion and calculates a user coordinate of the user according to the position information of the user U1 provided by the perception information capture device  120 _ 2  (step S 310 ). 
     In addition, the perception information capture devices  120 _ 1  to  120 _ 3  may capture position information of the target Obj1 (step S 312 ). Since the processing device  130 _ 2  has been selected as the first processing device, the processing device  130 _ 1  or the processing device  130 _ 3  may be selected as a second processing device (step S 314 ). The processing device  130 _ 3  as the second processing device will be taken as an example in the description below. The processing device  130 _ 3  may receive the position information and other relevant information of the target Obj1 to further process target identification related to the target Obj1 (step S 316 ). Next, the processing device  130 _ 3  performs coordinate conversion and calculates a target coordinate of the target Obj 1 according to the position information of the target Obj1 provided by the perception information capture devices  120 _ 1  to  120 _ 3  (step S 318 ), to convert the position information of the user U1 and the position information of the target Obj1 into the same coordinate system. The processing device  130 _ 3  may transmit the target coordinate of the target Obj1 through at least one of the gateways G1 to Gk to the processing device  130 _ 2  as the third processing device (step S320). 
     Lastly, the processing device  130 _ 2  determines display position information of the virtual object Vf1 according to the user coordinate and the target coordinate (step S 322 ), and controls the display  110 _ 2  to display the virtual object according to the display position information of the virtual object (step S 324 ). Accordingly, the processing device  130 _ 2  may display the virtual object Vf1 taking the display position information as a reference. 
       FIG.  4 A  is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure.  FIG.  4 B  is a flowchart of an information display method according to an exemplary embodiment of the disclosure. With reference to  FIG.  4 A  and  FIG.  4 B  together, in this embodiment, the user U1 is in front of the display  110 _ 3  and looks at the display  110 _ 1  located to the left of the user U1. 
     The perception information capture device  120 _ 3  may capture position information and posture information of the user U1 (step S 402 ), and transmit the position information and the posture information of the user U1 to the processing device  130 _ 3 , for example. The processing device  130 _ 3  may select a first processing device according to a distance between each of the processing devices  130 _ 1  to  130 _ 3  and the position information of the user U1 (step S 404 ). In this exemplary embodiment, the first processing device is the processing device  130 _ 3  that is closest in distance to the position information of the user U1 among the processing devices  130 _ 1  to  130 _ 3 . Next, the processing device  130 _ 3  as the first processing device may identify sight line information E2 of the user U1 according to the position information and the posture information of the user U1 (step S 406 ). In this exemplary embodiment, the processing device  130 _ 3  may determine that the sight line information E2 of the user U1 falls on the display  110 _ 1  according to the sight line information E2 of the user U1 and select a third processing device according to the display  110 _ 1  to which the sight line information E2 is pointed (step S 408 ). In this exemplary embodiment, the processing device  130 _ 1  for controlling the display  110 _ 1  is the third processing device. In other words, the first processing device and the third processing device are different in this exemplary embodiment. The processing device  130 _ 3  may transmit the sight line information E2 of the user U1 through at least one of the gateways G1 to Gk to the processing device  130 _ 1  as the third processing device (step S 410 ). 
     In addition, the perception information capture devices  120 _ 1  to  120 _ 3  may capture position information of a target Obj2 (step S 412 ). Since the processing device  130 _ 3  has been selected as the first processing device and the processing device  130 _ 1  has been selected as the third processing device, the processing device  130 _ 2  may be selected as a second processing device (step S 414 ). The processing device  130 _ 2  may receive the position information and other relevant information of the target Obj2 to further process target identification related to the target Obj2 (step S 416 ). Next, the processing device  130 _ 2  performs coordinate conversion and calculates a target coordinate of the target Obj2 according to the position information of the target Obj2 provided by the perception information capture devices  120 _ 1  to  120 _ 3  (step S 418 ). The processing device  130 _ 2  may transmit the target coordinate of the target Obj2 through at least one of the gateways G1 to Gk to the processing device  130 _ 1  as the third processing device (step S 420 ). 
     The processing device  130 _ 1  may receive the position information of the user U1 through the gateways G1 to Gk or directly from the perception information capture device  120 _ 1 . Therefore, the processing device  130 _ 1  performs coordinate conversion and calculates a user coordinate of the user according to the position information of the user U1 (step S 422 ). The processing device  130 _ 1  determines display position information of a virtual object Vf2 according to the user coordinate, the target coordinate, and the sight line information E2 (step S 424 ), and controls the display  110 _ 1  to display the virtual object Vf2 according to the display position information of the virtual object Vf2 (step S 426 ). In this exemplary embodiment, the processing device  130 _ 3  (i.e., the first processing device) may analyze the sight line information E2 of the user U1. The processing device  130 _ 2  (i.e., the second processing device) may process object identification and coordinate conversion on the target Obj2. The processing device  130 _ 1  (i.e., the third processing device) determines the display position information of the virtual object Vf2 according to the user coordinate and the target coordinate. 
     In some embodiments, the first processing device may calculate a viewing angle range corresponding to a certain display according to the position information of the user U1. The first processing device may identify the display looked at by the user U1 from the displays  110 _ 1  to  110 _ 3  in response to the sight line information of the user U1 falling within the viewing angle range. 
       FIG.  5 A  and  FIG.  5 B  are schematic diagrams of estimating a sight line position according to an exemplary embodiment of the disclosure. With reference to  FIG.  5 A  and  FIG.  5 B , a width of the display  110 _ 2  is dw. By disposing reference points P1 to P4 at known positions in front of the display  110 _ 2 , the processing device  130 _ 2  may estimate a lateral offset distance X of the user U1 from the left border of the display  110 _ 2  according to pixel positions of the reference points P1 to P4 on an image captured by the perception information capture device  120 _ 2 . The reference points P1 to P4 may be any identifier and is not limited by the disclosure. 
     Depth information of the reference points P1 to P2 is D1, and depth information of the reference points P3 to P4 is D2. The ratio of the result of subtracting an X-axis pixel coordinate D1 L  of the reference point P2 from an X-axis pixel coordinate D1 R  of the reference point P1 to the depth information D1 will be equal to the ratio of the result of subtracting an X-axis pixel coordinate Du L  from an X-axis pixel coordinate Du R  to depth information D. Similarly, the ratio of the result of subtracting an X-axis pixel coordinate D2 L  of the reference point P4 from an X-axis pixel coordinate D2 R  of the reference point P3 to the depth information D2 will be equal to the ratio of the result of subtracting the X-axis pixel coordinate Du L  from the X-axis pixel coordinate Du R  to the depth information D. Based on this, in the case where the X-axis pixel coordinate Du R  and the X-axis pixel coordinate Du L  can be known by calculation, the lateral offset distance X of the user U1 from the left border of the display  110 _ 2  can be obtained by, for example, interpolation calculation based on the depth information D of the user and the width dw. 
     As such, a viewing angle range θ may be calculated based on the lateral offset distance X, the depth information D, and the tangent function. As shown in  FIG.  5 B , if sight line information E3 of the user U1 does not fall within the viewing angle range θ, it indicates that the user U1 looks at the display  110 _ 1  to the left. Comparatively, if the sight line information of the user U1 falls within the viewing angle range θ, it indicates that the user U1 looks at the display  110 _ 2 . 
       FIG.  6 A  is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure.  FIG.  6 B  is a flowchart of an information display method according to an exemplary embodiment of the disclosure. With reference to  FIG.  6 A  and  FIG.  6 B  together, in this embodiment, the user U1 is located in front of the display  110 _ 2 , and switches from looking at the display  110 _ 2  located directly in front of the user U1 to looking at the display  110 _ 1  located to the left of the user U1. 
     The perception information capture device  120 _ 2  may capture position information and posture information of the user U1 (step S 602 ), and transmit the position information and the posture information of the user U1 to the processing device  130 _ 2 , for example. The processing device  130 _ 2  may select a first processing device according to a distance between each of the processing devices  130 _ 1  to  130 _ 3  and the position information of the user U1 (step S 604 ). In this exemplary embodiment, the first processing device may be the processing device  130 _ 2  that is closest in distance to the position information of the user U1 among the processing devices  130 _ 1  to  130 _ 3 . Next, the processing device  130 _ 2  as the first processing device may identify the sight line information E1 of the user U1 according to the position information and the posture information of the user U1 (step S 606 ). In this exemplary embodiment, the processing device  130 _ 2  may determine that the sight line information E1 of the user U1 falls on the display  110 _ 2  according to the sight line information E1 of the user U1 and select a third processing device according to the display  110 _ 1  to which the sight line information E1 is pointed (step S 608 ). In this exemplary embodiment, before the sight line information of the user U1 is changed, the processing device  130 _ 2  for controlling the display  110 _ 2  is also the third processing device. Therefore, the processing device  130 _ 2  calculates a user coordinate of the user (step S 610 ). The processing device  130 _ 2  determines display position information of the virtual object Vf1 (step S 612 ). The processing device  130 _ 2  controls the display  110 _ 2  to display the virtual object Vf1 (step S 614 ). The detailed operation specifics of step S 602  to step S 614  have been described in detail in the embodiments above, and will not be repeatedly described here. 
     Note that, in response to the user U1 turning around or turning his head, the processing device  130 _ 2  detects a change in sight line information of the user U1 (step S 616 ). In this exemplary embodiment, the sight line information E1 of the user is changed to the sight line information E3. After the sight line information of the user U1 is changed, the processing device  130 _ 2  determines whether the sight line information E3 of the user U1 still falls within a viewing angle range of one (i.e., the display  110 _ 2 ) of the displays  110 _ 1  to  110 _ 3  (step S 618 ). In response to the sight line information E3 of the user U1 not falling within the viewing angle range of the display  110 _ 2  (determined to be No in step S 618 ), the processing device  130 _ 2  identifies another one (i.e., the display  110 _ 1 ) of the displays  110 _ 1  to  110 _ 3  according to the sight line information E3 of the user to select another third processing device from the processing devices  130 _ 1  to  130 _ 3  according to the another one (i.e., the display  110 _ 1 ) of the displays  110 _ 1  to  110 _ 3  (step S 620 ). In this exemplary embodiment, after the sight line information of the user U1 is changed, the processing device  130 _ 1  for controlling the display  110 _ 1  is identified as another third processing device. Therefore, the processing device  130 _ 2  transmits the sight line information E3 to the processing device  130 _ 1  that is subsequently in charge of display control (step S 622 ). 
     In addition, the perception information capture devices  120 _ 1  to  120 _ 3  may capture position information of the targets Obj1 and Obj2 (step S 624 ). Since the processing device  130 _ 2  has been selected as the first processing device, the processing device  130 _ 3  may be selected as a second processing device (step S 626 ). The processing device  130 _ 3  may receive the position information and other relevant information of the targets Obj1 and Obj2 to further process target identification related to the targets Obj1 and Obj2 (step S 628 ). Next, the processing device  130 _ 3  performs coordinate conversion and calculates target coordinates of the targets Obj 1 and Obj2 according to the position information of the targets Obj 1 and Obj2 provided by the perception information capture devices  120 _ 1  to  120 _ 3  (step S 630 ). The processing device  130 _ 3  may transmit the target coordinates of the targets Obj1 and Obj2 through at least one of the gateways G1 to Gk to the processing device  130 _ 1  and the processing device  130 _ 2  as the third processing devices (step S 632 ). 
     Similar to the principle of operation above, the processing device  130 _ 1  performs coordinate conversion and calculates the user coordinate of the user according to the position information of the user U1 (step S 634 ). The processing device  130 _ 1  determines display position information of the virtual object Vf2 according to the user coordinate, the target coordinate, and the sight line information E3 (step S 636 ), and controls the display  110 _ 1  to display the virtual object Vf2 according to the display position information of the virtual object Vf2 (step S 638 ). In this exemplary embodiment, the third processing device in charge of display control is switched from the processing device  130 _ 2  to the processing device  130 _ 1  in response to a change in the sight line. 
       FIG.  7    is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure. With reference to  FIG.  7   , when the number of users exceeds one person, two of the processing devices  130 _ 1  to  130 _ 3  may serve as first processing devices for calculating the sight line information E2 and sight line information E4. In the exemplary embodiment of  FIG.  7   , since the perception information capture device  120 _ 1  detects a user U2, the processing device  130 _ 1  that is closest in distance to the user U2 is selected as the first processing device for calculating the sight line information E4 of the user U2. In addition, since the perception information capture device  120 _ 1  detects the user U1, the processing device  130 _ 3  that is closest in distance to the user U1 is selected as the first processing device for calculating the sight line information E2 of the user U1. In addition, the processing devices  130 _ 1  and  130 _ 2  may be respectively configured to calculate display position information of the virtual objects Vf1 and Vf2 according to the sight line positions of the sight line information E2 and E4 of the users U1 and U2 pointed on the displays  110 _ 1  and  110 _ 2 . 
       FIG.  8 A  is a schematic diagram of an application scenario of an information display system according to an exemplary embodiment of the disclosure.  FIG.  8 B  is a flowchart of an information display method according to an exemplary embodiment of the disclosure. With reference to  FIG.  8 A  and  FIG.  8 B  together, in this embodiment, the user U1 and a plurality of other users U3 and U4 are located in front of the display  110 _ 3 , and the user U1 and the other users U3 and U4 all look at the display  110 _ 1  to the left. 
     The perception information capture device  120 _ 3  may capture position information and posture information of the user U1 and the other users U3 and U4 (step S 802 ), and transmit the position information and the posture information of the user U1 and the other users U3 and U4 to the processing device  130 _ 3 , for example. In this embodiment, the processing device  130 _ 3  may select a first processing device according to a distance between each of the processing devices  130 _ 1  to  130 _ 3  and the position information of the user U1 and the other users U3 and U4 (step S 804 ). The processing device  130 _ 3  may calculate the distance between the processing devices  130 _ 1  to  130 _ 3  and the user U1. Similarly, the processing device  130 _ 3  may calculate the respective distances between the processing devices  130 _ 1  to  130 _ 3  and the other users U3 and U4. The processing device  130 _ 3  may find a minimum distance among the distances above and select the processing device associated with the minimum distance as the first processing device. In this exemplary embodiment, since the user U1 is at a minimum distance from the processing device  130 _ 3 , the processing device  130 _ 3  is selected as the first processing device. 
     Next, the processing device  130 _ 3  as the first processing device may identify the sight line information E3 of the user U1 and sight line information E5 and E6 of the other users U3 and U4 according to the position information and the posture information of the user U1 and the other users U3 and U4 (step S 806 ). 
     The processing device  130 _ 3  determines whether one (i.e., the perception information capture device  120 _ 3 ) of the perception information capture devices  120 _ 1  to  120 _ 3  detects the user U1 and the other users U3 and U4 at the same time (step S 808 ). In response to the perception information capture device  120 _ 3  detecting the user U1 and the other users U3 and U4 at the same time (determined to be Yes in step S 808 ), the processing device  130 _ 3  calculates a common sight line direction according to the sight line information E3 of the user U1 and the sight line information E5 and E6 of the other users U3 and U4 (step S 810 ), and selects a third processing device from the processing devices  130 _ 1  to  130 _ 3  and selects one of the displays  110 _ 1  to  110 _ 3  according to the common sight line direction (step S 812 ). In some embodiments, the processing device  130 _ 3  may calculate the average of the components of the sight line information E3 of the user U1 and the sight line information E5 and E6 of the other users U3 and U4 in each axial direction to obtain the common sight line direction. 
     In some embodiments, before calculating the common sight line direction, the processing device  130 _ 3  may also determine whether a sight line direction difference between the sight line information E3 of the user U1 and the sight line information E5 and E6 of the other users U3 and U4 meets a predetermined condition. The processing device  130 _ 3  may determine whether the angular difference between the sight line vector of the user U1 and the sight line vectors of the other users U3 and U4 is less than a threshold. If so, the sight line direction difference between the sight line information E3 of the user U1 and the sight line information E5 and E6 of the other users U3 and U4 may be determined to meet the predetermined condition, indicating that the user U1 and the other users U3 and U4 look at a similar position. 
     Furthermore, in this exemplary embodiment, since the common sight line direction falls on the display  110 _ 1 , the processing device  130 _ 3  selects the third processing device according to the display  110 _ 1  to which the common sight line direction is pointed. In this exemplary embodiment, the processing device  130 _ 1  for controlling the display  110 _ 1  is the third processing device. The processing device  130 _ 3  may transmit the common sight line direction through at least one of the gateways G1 to Gk to the processing device  130 _ 1  as the third processing device (step S 814 ). 
     In addition, the perception information capture devices  120 _ 1  to  120 _ 3  may capture position information of the target Obj2 (step S 816 ). Since the processing device  130 _ 3  has been selected as the first processing device and the processing device  130 _ 1  has been selected as the third processing device, the processing device  130 _ 2  may be selected as a second processing device (step S 818 ). The processing device  130 _ 2  may receive the position information and other relevant information of the target Obj2 to further process target identification related to the target Obj2 (step S 820 ). Next, the processing device  130 _ 2  performs coordinate conversion and calculates a target coordinate of the target Obj2 according to the position information of the target Obj2 provided by the perception information capture devices  120 _ 1  to  120 _ 3  (step S 822 ). The processing device  130 _ 2  may transmit the target coordinate of the target Obj2 through at least one of the gateways G1 to Gk to the processing device  130 _ 1  as the third processing device (step S 824 ). 
     The processing device  130 _ 1  may receive the position information of the user U1 through the gateways G1 to Gk or directly from the perception information capture device  120 _ 1 . Therefore, the processing device  130 _ 1  performs coordinate conversion and calculates a user coordinate of the user according to the position information of the user U1 (step S 826 ). The processing device  130 _ 1  determines display position information of the virtual object Vf2 according to the user coordinate, the target coordinate, and the common sight line direction (step S 828 ), and controls the display  110 _ 1  to display the virtual object Vf2 according to the display position information of the virtual object Vf2 (step S 830 ). 
       FIG.  9    is a block diagram of a processing device according to an exemplary embodiment of the disclosure. A processing device  900  may be the processing devices  130 _ 1  to  130 _N of the embodiments above. With reference to  FIG.  9   , the processing device  900  may include a memory  901 , a processor  902 , and a transmission element  903 . For example, the memory  901  may be any type of fixed or removable random access memory (RAM), read-only memory (ROM), flash memory, hard disks, or other similar devices, integrated circuits, or a combination thereof. For example, the processor  902  may be a central processing unit (CPU), an application processor (AP), or any other programmable general-purpose or special-purpose microprocessor, a digital signal processor (DSP), an image signal processor (ISP), a graphics processing unit (GPU), or other similar devices, integrated circuits, or a combination thereof. The transmission element  903  is a communication device supporting wired/wireless transmission protocols, such as a combination of a transceiver and an antenna. The processor  902  may execute commands, programming codes, or software modules recorded in the memory  901  to realize the information display method of the embodiments of the disclosure. 
     In the information display method, the information display system, and the processing device according to the exemplary embodiments of the disclosure, computing may be allocated to a plurality of processing devices according to the position and the sight line of the user, to improve computational efficiency and prevent delay in display services of merged virtuality and reality. Accordingly, the virtual object can be smoothly displayed in real time, improving the viewing experience of the user. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.