Patent Publication Number: US-11392197-B2

Title: Image rendering method, device, system, storage medium, image display method and computer device

Description:
The present application claims priority of Chinese Patent Application No. 201810466112.4, filed on May 16, 2018, the disclosure of which is incorporated herein by reference in its entirety as part of the present application. 
     TECHNICAL FIELD 
     Embodiments of the present disclosure relate to an image rendering method for virtual reality, an image rendering device, an image rendering system, a computer readable storage medium, a computer device, and an image display method. 
     BACKGROUND 
     At present, the requirements for display definition, especially for the display definition of virtual reality (VR)/augmented reality (AR), are getting higher and higher, and an information amount of images, which are output by computer devices to display devices, is also getting larger and larger. For a high definition resolution rendering scene, there are great requirements for software computing speed, consumption of computing resources, and a transmission data amount of image data. For human eyes, because a concentration of cone cells on a retina responsible for observing colors and a concentration of cone cells on the retina responsible for observing details are different, details only in a center of a gaze point of the human eyes can be accepted, and any area, which is beyond a gaze area of human eyes by 5°, in the image will gradually reduce the definition. 
     With the development of display technology, a method, which performs compression processing based on algorithm on an image, cannot meet the demand due to poor real-time performance and large consumption of computing resources. How to improve the real-time performance and computational efficiency of image compression transmission becomes an urgent problem to be solved when saving the transmission bandwidth in the image transmission process. 
     SUMMARY 
     At least one embodiment of the present disclosure provides an image rendering method for virtual reality, comprising: acquiring an image to be displayed; according to a gaze point of human eyes on a display screen of a virtual reality device, obtaining a gaze point position, which corresponds to the gaze point, on the image to be displayed; determining, according to the gaze point position, a first sampling area and a second sampling area of the image to be displayed; performing first resolution sampling on the first sampling area to obtain a first display area; performing second resolution sampling on the image to be displayed to obtain a second display area corresponding to the second sampling area, in which a resolution of the second sampling area is greater than a resolution of the second display area; and splicing the first display area and the second display area to obtain an output image to be transmitted to the virtual reality device. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, performing the first resolution sampling on the first sampling area and performing the second resolution sampling on the image to be displayed comprises: determining a rendering model according to the gaze point position, in which the rendering model comprises an original resolution sampling area, a compression resolution sampling area, and a resolution compression multiple of the compression resolution sampling area, the original resolution sampling area corresponds to the first sampling area, and the compression resolution sampling area corresponds to the second sampling area; and according to the rendering model, performing the first resolution sampling on the first sampling area and performing the second resolution sampling on the image to be displayed. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, determining the rendering model according to the gaze point position comprises: acquiring an original rendering model, in which the original rendering model comprises an original original-resolution sampling area and an original compression resolution sampling area; and according to the gaze point position, adjusting a center point position of the original original-resolution sampling area and a resolution compression multiple of the original compression resolution sampling area to obtain the rendering model. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, the resolution compression multiple of the original compression resolution sampling area is preset and adjusted according to a positional relationship between the original compression resolution sampling area and the original original-resolution sampling area. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, the resolution compression multiple of the compression resolution sampling area comprises a transverse resolution compression multiple and/or a longitudinal resolution compression multiple. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, the original resolution sampling area and the compression resolution sampling area form a nine-grid structure, the nine-grid structure comprises a plurality of areas arranged in three rows and three columns, and the original resolution sampling area is located in a second row and a second column of the nine-grid structure. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, a size of the first sampling area, a size of the original original-resolution sampling area, and a size of the original resolution sampling area are identical. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, adjusting the center point position of the original original-resolution sampling area comprises: in a case where a center point of the original original-resolution sampling area is the gaze point position, judging whether the original original-resolution sampling area exceeds a boundary of the image to be displayed: if not, adjusting the center point of the original original-resolution sampling area to be the gaze point position; and if yes, adjusting the center point of the original original-resolution sampling area to be a position closest to the gaze point position in a case where the original original-resolution sampling area does not exceed the boundary of the image to be displayed. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, according to the rendering model, performing the second resolution sampling on the image to be displayed, comprises: according to the rendering model, performing the second resolution sampling on the image to be displayed to obtain an intermediate image to be displayed; and according to a positional relationship between the first sampling area and the second sampling area and a proportional relationship between the first sampling area and the second sampling area, dividing the intermediate image to be displayed to obtain a first intermediate display area corresponding to the first sampling area and a second intermediate display area corresponding to the second sampling area, in which the second display area comprises the second intermediate display area. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, acquiring the image to be displayed comprises: acquiring an original image; and performing an inverse-distortion processing on the original image to obtain the image to be displayed. 
     For example, in the image rendering method provided by some embodiments of the present disclosure, a resolution of the first sampling area is equal to a resolution of the first display area. 
     At least some embodiments of the present disclosure also provide an image display method, comprising: in a rendering engine: acquiring an image to be displayed; according to a gaze point of human eyes on a display screen of a virtual reality device, obtaining a gaze point position, which corresponds to the gaze point, on the image to be displayed; determining, according to the gaze point position, a first sampling area and a second sampling area of the image to be displayed; performing first resolution sampling on the first sampling area to obtain a first display area; performing second resolution sampling on the image to be displayed to obtain a second display area corresponding to the second sampling area, in which a resolution of the second sampling area is greater than a resolution of the second display area; splicing the first display area and the second display area to obtain an output image; and transmitting the output image to the virtual reality device; and in the virtual reality device, stretching the output image by the virtual reality device to obtain a stretched image; and displaying the stretched image on the display screen of the virtual reality device. 
     For example, in the image display method provided by at least some embodiments of the present disclosure, the output image comprises the first display area and the second display area, and stretching the output image by the virtual reality device to obtain the stretched image comprises: stretching the second display area in the output image by the virtual reality device to obtain a stretched display area; and determining the stretched image according to the first display area and the stretched display area. 
     Some embodiments of the present disclosure also provide an image rendering device for virtual reality, comprising a gaze point projection module, a rendering engine, and a splicing module; the gaze point projection module is configure to obtain, according to a gaze point of human eyes on a display screen of a virtual reality device, a gaze point position, which corresponds to the gaze point, on the image to be displayed; the rendering engine is configure to: determine, according to the gaze point position, a first sampling area and a second sampling area of the image to be displayed; perform first resolution sampling on the first sampling area to obtain a first display area; and perform second resolution sampling on the image to be displayed to obtain a second display area corresponding to the second sampling area, in which a resolution of the second sampling area is greater than a resolution of the second display area; and the splicing module is configured to splice the first display area and the second display area to obtain an output image to be transmitted to the virtual reality device. 
     For example, in the image rendering device provided by at least some embodiments of the present disclosure, the rendering engine is further configured to: load a rendering model, that is, determine the rendering model, according to the gaze point position, in which the rendering model comprises an original resolution sampling area, a compression resolution sampling area, and a resolution compression multiple of the compression resolution sampling area, the original resolution sampling area corresponds to the first sampling area, and the compression resolution sampling area corresponds to the second sampling area; and according to the rendering model, perform the first resolution sampling on the first sampling area and perform the second resolution sampling on the image to be displayed. 
     For example, the image rendering device provided by at least some embodiments of the present disclosure further comprises an adjustment module; the rendering engine is further configured to acquire an original rendering model, in which the original rendering model comprises an original original-resolution sampling area and an original compression resolution sampling area; and the adjustment module is configured to, according to the gaze point position, adjust a center point position of the original original-resolution sampling area and a resolution compression multiple of the original compression resolution sampling area to determine the rendering model. 
     Some embodiments of the present disclosure also provide an image rendering system for virtual reality, including: a virtual reality device and the image rendering device described in any one of the above embodiments; the virtual reality device is configured to acquire the gaze point of the human eyes on the display screen of the virtual reality device and receive the output image transmitted by the image rendering device. 
     Some embodiments of the present disclosure also provide a computer readable storage medium which is stored a computer program, in a case where the computer program is executed by a processor, the image rendering method provided by any one of embodiments of the present disclosure is implemented. 
     Some embodiments of the present disclosure also provide a computer device comprising: a memory configured to store a computer program; and a processor configured to execute the computer program; in a case where the computer program is executed by the processor, the image rendering method provided by any one of embodiments of the present disclosure is implemented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described in the following; it is obvious that the described drawings are only related to some embodiments of the present disclosure and thus are not limitative to the present disclosure. 
         FIG. 1A  shows a flowchart of an image rendering method for virtual reality provided by at least some embodiments of the present disclosure; 
         FIG. 1B  shows another flowchart of an image rendering method for virtual reality provided by at least some embodiments of the present disclosure; 
         FIG. 2A  shows an implementation principle diagram of a rendering process provided by at least some embodiments of the present disclosure; 
         FIG. 2B  shows a schematic diagram of a rendering model provided by at least some embodiments of the present disclosure; 
         FIG. 3  shows a change process diagram of an image during a process of an image rendering method for virtual reality provided by at least some embodiments of the present disclosure; 
         FIG. 4A  shows a schematic diagram of an original rendering model provided by some embodiments of the present disclosure; 
         FIG. 4B  shows a schematic diagram of a rendering model provided by some embodiments of the present disclosure; 
         FIG. 5A  is a schematic diagram of a positional relationship between a gaze point position and an original resolution sampling area on an image to be displayed provided by some embodiments of the present disclosure; 
         FIG. 5B  is a schematic diagram of another positional relationship between a gaze point position and an original resolution sampling area provided by some embodiments of the present disclosure; 
         FIG. 5C  is a schematic diagram of a center of an original resolution sampling area after being adjusted provided by some embodiments of the present disclosure; 
         FIG. 6  is a schematic flowchart of an image display method provided by some embodiments of the present disclosure; 
         FIG. 7  is a schematic diagram of rendering models and output images corresponding to different gaze point positions provided by some embodiments of the present disclosure; 
         FIG. 8  shows a structural schematic diagram of an image rendering device for virtual reality provided by at least some embodiments of the present disclosure; 
         FIG. 9  shows a schematic diagram of an image rendering system for virtual reality provided by at least some embodiments of the present disclosure; and 
         FIG. 10  shows a structural schematic diagram of a computer device provided by at least some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In order to make objects, technical details and advantages of the embodiments of the present disclosure apparent, the technical solutions of the embodiments will be described in a clearly and fully understandable way in connection with the drawings related to the embodiments of the present disclosure. Apparently, the described embodiments are just a part but not all of the embodiments of the present disclosure. Based on the described embodiments herein, those skilled in the art can obtain other embodiment(s), without any inventive work, which should be within the scope of the present disclosure. 
     Unless otherwise defined, all the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. The terms “first,” “second,” etc., which are used in the present disclosure, are not intended to indicate any sequence, amount or importance, but distinguish various components. The terms “comprise,” “comprising,” “comprise,” “including,” etc., are intended to specify that the elements or the objects stated before these terms encompass the elements or the objects and equivalents thereof listed after these terms, but do not preclude the other elements or objects. The phrases “connect”, “connected”, etc., are not intended to define a physical connection or mechanical connection, but may comprise an electrical connection, directly or indirectly. “On,” “under,” “right,” “left” and the like are only used to indicate relative position relationship, and when the absolute position of the object which is described is changed, the relative position relationship may be changed accordingly. 
     In order to explain the present disclosure more clearly, the present disclosure will be further described below with reference to some embodiments of the present disclosure and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the following detailed description is illustrative rather than limiting, and should not be intended to limit the scope of protection of the present disclosure. 
       FIG. 1A  shows a flowchart of an image rendering method for virtual reality provided by at least some embodiments of the present disclosure;  FIG. 1B  shows another flowchart of an image rendering method for virtual reality provided by at least some embodiments of the present disclosure;  FIG. 2A  shows an implementation principle diagram of a rendering process provided by at least some embodiments of the present disclosure;  FIG. 2B  shows a schematic diagram of a rendering model provided by at least some embodiments of the present disclosure; and  FIG. 3  shows a change process diagram of an image during a process of an image rendering method for virtual reality provided by at least some embodiments of the present disclosure. 
     Some embodiments of the present disclosure provide an image rendering method, the image rendering method can be applied to a virtual reality device. For example, as shown in  FIG. 1B , some embodiments of the present disclosure provide an image rendering method for virtual reality, which includes: 
     according to a gaze point position of human eyes on a display screen of a virtual reality device, obtaining a position, which corresponds to a gaze point, on an image to be displayed on the display screen; in which obtaining the position of the gaze point on the display screen can be achieved by the virtual reality device, to which the display screen belongs, through a corresponding hardware or software based on gaze tracking technology; 
     loading a rendering model, in which the rendering model is preset with an original resolution sampling area, a compression resolution sampling area, and a transverse resolution compression multiple and/or a longitudinal resolution compression multiple of the compression resolution sampling area; 
     according to the position, which corresponds to the gaze point, on the image to be displayed on the display screen, adjusting a center point position of the original resolution sampling area and the transverse resolution compression multiple and/or the longitudinal resolution compression multiple of the compression resolution sampling area; 
     according to the rendering model which is adjusted, performing original resolution sampling on the original resolution sampling area of the image and performing compression resolution sampling on the compression resolution sampling area; and 
     splicing the original resolution sampling area which is sampled and the compression resolution sampling area to obtain an image to be transmitted to the virtual reality device. 
     For example, as shown in  FIG. 1A , other embodiments of the present disclosure provide an image rendering method for virtual reality, which includes: 
     S 10 : acquiring an image to be displayed; 
     S 11 : according to a gaze point of human eyes on a display screen of a virtual reality device, obtaining a gaze point position, which corresponds to the gaze point, on the image to be displayed; 
     S 12 : determining, according to the gaze point position, a first sampling area and a second sampling area of the image to be displayed; 
     S 13 : performing first resolution sampling on the first sampling area to obtain a first display area; 
     S 14 : performing second resolution sampling on the image to be displayed to obtain a second display area corresponding to the second sampling area; 
     S 15 : splicing the first display area and the second display area to obtain an output image to be transmitted to the virtual reality device. 
     The image rendering method for virtual reality provided by the embodiment of the present disclosure can be implemented in a rendering engine. By adjusting a rendering model in the rendering engine, an non-high definition area (i.e., a non-gaze point area) of the image can be compressed in the rendering engine, so that a transmission bandwidth output by a software terminal to the display device is reduced, the transmission bandwidth in the image transmission process can be saved, and a problem that the real-time display with high resolution and high refresh rate cannot be completed, because direct transmission of 4K images has too much pressure on hardware due to the limitation of the transmission bandwidth, is solved. And compared with a method of compressing images based on an algorithm, the image rendering method provided by the present disclosure has high real-time performance, fast calculation speed, small calculation resource consumption, and high calculation efficiency, and can achieve real-time display with high resolution and high refresh rate. 
     For example, in step S 10 , the image to be displayed may be acquired by the rendering engine. In some embodiments, step S 10  may include: acquiring an original image; performing an inverse-distortion processing on the original image to obtain the image to be displayed. As shown in  FIG. 1B , after starting to execute the program, the rendering engine can obtain a rendering image, i.e. the original image, of a current scene, and then, the rendering engine can also perform the inverse-distortion processing on the rendering image to obtain the image to be displayed, that is, the image to be displayed is an inverse-distortion image. 
     In a case where the image rendering method is applied to the virtual reality device, especially a virtual reality head-mounted display device, because the display screen of the virtual reality device is usually equipped with lenses, in order to display normally, the inverse-distortion processing needs to be performed on the image. By adding the above step of performing the inverse-distortion processing to the image rendering method for virtual reality provided by this embodiment, it can be achieved that the method is applied to the image transmission from a computer device to the virtual reality device. 
     For example, a size of the image to be displayed may be identical to a size of the original image. 
     For example, the original image may be a color image or a grayscale image. For example, the original image may have various shapes, such as rectangle, circle, trapezoid, etc. An embodiment of the present disclosure will be described below by taking a case that both the original image and the image to be displayed have a rectangular shape as an example. 
     For example, in step S 11 , the position, which corresponds to the gaze point, on the image to be displayed on the display screen is obtained according to the gaze point position of the human eyes on the display screen of the virtual reality device. For example, obtaining the gaze point position of the gaze point on the display screen can be implemented by the virtual reality device, to which the display screen belongs, through a corresponding hardware or software based on the gaze tracking technology. The virtual reality device can track the line of sight of the human eyes according to the changes in characteristics of the eyeball and the periphery of the eyeball. The virtual reality device can also track the line of sight of the human eyes according to changes of an iris angle. The virtual reality device can also actively project infrared rays or other light beams to the iris to extract eyeball features, thereby achieving to track the line of sight of the human eyes. 
     For example, in some examples, the virtual reality device implements to track the line of sight of the human eyes through a corresponding software based on the gaze tracking technology. As shown in  FIG. 1B , after the program is started to be executed, the virtual reality device can execute gaze tracking programs to obtain a gaze point of an eyeball at a current situation. 
     For example, in step S 12 , a size of the first sampling area can be preset by users, and during a process of executing the program, the size of the first sampling area remains unchanged for different images to be displayed. 
     For example, the second sampling area may be determined according to the gaze point position and the size of the first sampling area. 
     For example, in steps S 13  and S 14 , performing the first resolution sampling on the first sampling area and performing the second resolution sampling on the image to be displayed includes: loading a rendering model according to the gaze point position, i.e., determining the rendering model, in which the rendering model includes an original resolution sampling area, a compression resolution sampling area, and a resolution compression multiple of the compression resolution sampling area, the original resolution sampling area corresponds to the first sampling area, and the compression resolution sampling area corresponds to the second sampling area; and according to the rendering model, performing the first resolution sampling on the first sampling area and performing the second resolution sampling on the image to be displayed. 
     For example, in steps S 13  and S 14 , a resolution of the first sampling area is equal to a resolution of the first display area, that is, a size of the first display area is identical to a size of the first sampling area. A resolution of the second sampling area is greater than a resolution of the second display area, that is, a size of the second sampling area is greater than a size of the second display area. That is, in steps S 13  and S 14 , the first display area can be obtained by performing original resolution sampling on the first sampling area, and the second display area can be obtained by performing compression resolution sampling on the second sampling area. 
     For example, the compression resolution sampling can be implemented by an interpolation algorithm. The interpolation algorithm includes, for example, Lagrange interpolation, Newton interpolation, Hermite interpolation, etc. 
     For example, as shown in  FIG. 1B , the inverse distortion image (i.e., the image to be displayed) of a high definition area (i.e., the first sampling area) may be sampled according to the gaze point position. Low resolution sampling may be performed on the entire image to be displayed to obtain an inverse distortion image, which is compressed, of an entire area (i.e., an area of the entire image to be displayed). 
     For example, as shown in  FIG. 2A , in some embodiments, a resolution of the image to be displayed  20  may be 4320*4800. A resolution of the output image  30  obtained by processing the image to be displayed  20  according to the embodiment of the present disclosure is 2160*2400. 
     For example, the output image  30  includes a first display area and a second display area. As shown in  FIG. 2A , in some examples, the output image  30  includes nine output sub-areas, the first display area is an output sub-area  15 , and the second display area includes eight output sub-areas, that is, the second display area may include an output sub-area  11 , an output sub-area  12 , an output sub-area  13 , an output sub-area  14 , an output sub-area  16 , an output sub-area  17 , an output sub-area  18 , and an output sub-area  19 . 
     For example, the output sub-area  15  of the output image  30  corresponds to a sub-area to be displayed  5  of the image to be displayed  20 , the output sub-area  11  of the output image  30  corresponds to a sub-area to be displayed  1  of the image to be displayed  20 , the output sub-area  12  of the output image  30  corresponds to a sub-area to be displayed  2  of the image to be displayed  20 , the output sub-area  13  of the output image  30  corresponds to a sub-area to be displayed  3  of the image to be displayed  20 , the output sub-area  14  of the output image  30  corresponds to a sub-area to be displayed  4  of the image to be displayed  20 , the output sub-area  16  of the output image  30  corresponds to a sub-area to be displayed  6  of the image to be displayed  20 , the output sub-area  17  of the output image  30  corresponds to a sub-area to be displayed  7  of the image to be displayed  20 , the output sub-area  18  of the output image  30  corresponds to a sub-area to be displayed  8  of the image to be displayed  20 , and the output sub-area  19  of the output image  30  corresponds to a sub-area to be displayed  9  of the image to be displayed  20 . A resolution of the output sub-area  15  of the output image  30  is identical to a resolution of the sub-area to be displayed  5  of the image to be displayed  20 . A resolution of each output sub-area in the second display area is smaller than a resolution of a corresponding sub-area to be displayed in the second sampling area. For example, a resolution of the output sub-area  11  of the output image  30  is less than a resolution of the sub-area to be displayed  1  of the image to be displayed  20 . 
     For example, the image to be displayed  20  has a rectangular shape, the first sampling area may be located at any corner of the rectangle, and the first sampling area may be located at any edge of the rectangle; alternatively, the first sampling area may also be located at the middle of the rectangle, that is, the first sampling area is not in contact with the edges and corners of the image to be displayed  20 . The embodiments of the present disclosure do not limit the specific position of the second sampling area. 
     For example, the second sampling area may include a plurality of sub-areas to be displayed. 
     For example, as shown in  FIG. 2A , in some examples, the first sampling area  21  may be located at the middle of the image to be displayed, in this case, the image to be displayed  20  is divided into nine sub-areas to be displayed, the first sampling area  21  is the sub-area to be displayed  5 , and the second sampling area  22  includes eight sub-areas to be displayed, that is, the second sampling area  22  may include the sub-area to be displayed  1 , the sub-area to be displayed  2 , the sub-area to be displayed  3 , the sub-area to be displayed  4 , the sub-area to be displayed  6 , the sub-area to be displayed  7 , the sub-area to be displayed  8 , and the sub-area to be displayed  9 . The first sampling area  21  and the second sampling area  22  form a nine-grid structure, the nine-grid structure includes a plurality of areas arranged in three rows and three columns, and the first sampling area  21  is located at a center of the nine-grid structure, namely, the first sampling area  21  is located in a second row and a second column of the nine-grid structure. 
     It is worth noting that each sub-area to be displayed can be further divided. 
     For example, as shown in  FIG. 2A , the sub-area to be displayed  1 , the sub-area to be displayed  3 , the sub-area to be displayed  7 , and the sub-area to be displayed  9  of the second sampling area  22  are not adjacent to the first sampling area  21  (i.e., the sub-area to be displayed  5 ), the sub-area to be displayed  4  and the sub-area to be displayed  6  of the second sampling area  22  are adjacent to the first sampling area  21  in a second direction, and the sub-area to be displayed  2  and the sub-area to be displayed  8  of the second sampling area  22  are adjacent to the first sampling area  21  in a first direction. 
     For example, the first direction and the second direction are perpendicular to each other. 
     For example, as shown in  FIG. 2B , in other examples, the first sampling area  21  is located at any corner of the rectangle. At this time, as shown in  FIG. 2B , the image to be displayed  20  can be divided into four sub-areas to be displayed, the first sampling area  21  is a sub-area to be displayed A, and the second sampling area  22  includes three sub-areas to be displayed, that is, the second sampling area  22  may include a sub-area to be displayed B, a sub-area to be displayed C, and a sub-area to be displayed D. However, the present disclosure is not limited to this case. The first sampling area  21  may also be the sub-area to be displayed C, and accordingly, the second sampling area  21  includes the sub-area to be displayed A, the sub-area to be displayed B, and the sub-area to be displayed D. 
     For example, as shown in  FIG. 2B , the sub-area to be displayed B of the second sampling area  22  is adjacent to the first sampling area  21  (i.e., the sub-area to be displayed A) in the first direction, the sub-area to be displayed C of the second sampling area  22  is adjacent to the first sampling area  21  in the second direction, and the sub-area to be displayed D of the second sampling area  22  is not adjacent to the first sampling area  21 . 
     It should be noted that in the present disclosure, the term “adjacent” may mean that the sub-area to be displayed (e.g., the sub-area to be displayed B and the sub-area to be displayed C as shown in  FIG. 2B ) in the second sampling area  22  is adjacent to at least one edge of the first sampling area  21 . The term “not adjacent” means that the sub-area to be displayed (e.g., the sub-area to be displayed D as shown in  FIG. 2B ) in the second sampling area  22  is not adjacent to either edge of the first sampling area  21 . 
     For example, step S 14  may include: according to the rendering model, performing the second resolution sampling on the image to be displayed to obtain an intermediate image to be displayed; and according to a positional relationship between the first sampling area and the second sampling area and a proportional relationship between the first sampling area and the second sampling area, dividing the intermediate image to be displayed to obtain a first intermediate display area corresponding to the first sampling area and a second intermediate display area corresponding to the second sampling area. The second display area includes the second intermediate display area. 
     For example, as shown in  FIG. 3 , in step 3 , the second resolution sampling is performed on the image to be displayed  20  to obtain the intermediate image to be displayed  26 . The intermediate image to be displayed  26  is an image obtained by compressing the entire image to be displayed  20 , and then, the intermediate image to be displayed  26  can be divided according to the positional relationship between the first sampling area and the second sampling area and the proportional relationship between the first sampling area and the second sampling area. For example, for the example shown in  FIG. 2A , that is, in a case where the second sampling area includes the sub-area to be displayed  1 , the sub-area to be displayed  2 , the sub-area to be displayed  3 , the sub-area to be displayed  4 , the sub-area to be displayed  6 , the sub-area to be displayed  7 , the sub-area to be displayed  8 , and the sub-area to be displayed  9 , and the first sampling area is the sub-area to be displayed  5 , the intermediate image to be displayed  26  can also be divided into nine intermediate sub-areas, and the nine intermediate sub-areas are arranged in three rows and three columns. The first intermediate display area includes an intermediate sub-area located in a second column and a second row, the second intermediate display area includes eight intermediate sub-areas, and the eight intermediate sub-areas are in one-to-one correspondence with the eight sub-areas to be displayed of the second sampling area. For example, an intermediate sub-area, which is located in a first column and a first row, of the second intermediate display area corresponds to the sub-area to be displayed  1  of the second sampling area, that is, both a position of the intermediate sub-area, which is located in the first column and the first row, of the second intermediate display area in the intermediate image to be displayed  26  and a proportional relationship between the intermediate sub-area which is located in the first column and the first row and the remaining intermediate sub-areas are identical to a position of the sub-area to be displayed  1  of the second sampling area in the image to be displayed  20  and a proportional relationship between the sub-area to be displayed  1  and the remaining sub-areas to be displayed. 
       FIG. 4A  is a schematic diagram of an original rendering model provided by some embodiments of the present disclosure; and  FIG. 4B  is a schematic diagram of a rendering model provided by some embodiments of the present disclosure. 
     For example, in some embodiments, in step S 15 , in a case where the rendering model is determined, the first display area is placed at a position corresponding to the original resolution sampling area and the second display area is placed at a position corresponding to the compression resolution sampling area, thereby obtaining the output image. For example, as shown in  FIG. 1B , the high definition image (i.e., the first display area) and an area, which corresponds to the second display area, in the original image are pasted onto a multi-resolution rendering model in proportion to obtain the output image. 
     For example, determining the rendering model according to the gaze point position includes: acquiring an original rendering model, in which the original rendering model includes an original original-resolution sampling area and an original compression resolution sampling area; and according to the gaze point position, adjusting a center point position of the original original-resolution sampling area and a resolution compression multiple of the original compression resolution sampling area to obtain the rendering model. 
     For example, as shown in  FIG. 1B , before starting to execute the program, a multi-resolution original rendering model can be created by a modeling software, and then the original rendering model can be imported into the rendering engine for subsequent use. In the process of executing the program, the rendering engine can modify a shape of the original rendering model according to the gaze point position to obtain a required rendering model. For example, modifying the shape of the original rendering model may include adjusting the center point position of the original original-resolution sampling area and a resolution compression multiple of the original compression resolution sampling area. For example, the shape of the rendering model and the shape of the original rendering model can also be rectangular. 
     For example, a size of the rendering model is identical to a size of the original rendering model. The size of the rendering model is also identical to the size of the output image. 
     For example, in some alternative implementations of this embodiment, the resolution compression multiple of the original compression resolution sampling area may be preset and adjusted according to a positional relationship between the original compression resolution sampling area and the original original-resolution sampling area. 
     For example, the resolution compression multiple of the compression resolution sampling area may include a transverse resolution compression multiple and/or a longitudinal resolution compression multiple. For example, as shown in  FIGS. 4A and 4B , the longitudinal resolution compression multiple may represent a resolution compression multiple in the first direction, and the transverse resolution compression multiple may represent a resolution compression multiple in the second direction. 
     It should be noted that in the embodiment of the present disclosure, in a case where the resolution compression multiple is greater than 1, it means that the original compression resolution sampling area is compressed; and in a case where the resolution compression multiple is less than 1, it means that the original compression resolution sampling area is stretched. 
     For example, in the rendering model, the original resolution sampling area corresponds to an area corresponding to the position of the gaze point on the image to be displayed, and the other area that the user does not pay attention to (i.e. non-gaze area) is set as the compression resolution sampling area. That is, the original resolution sampling area corresponds to the first display area of the output image, i.e., the original resolution sampling area corresponds to the output sub-area  15  as shown in  FIG. 2A , and the compression resolution sampling area corresponds to the second display image of the output image, i.e., the output sub-area  11 , the output sub-area  12 , the output sub-area  13 , the output sub-area  14 , the output sub-area  16 , the output sub-area  17 , the output sub-area  18 , and the output sub-area  19  as shown in  FIG. 2A . In order to ensure that the virtual camera performs original resolution sampling on the original resolution sampling area of the image, in a case of presetting and adjusting the transverse resolution compression multiple and the longitudinal resolution compression multiple of each compression resolution sampling area, it is necessary to consider the positional relationship between each compression resolution sampling area and the original resolution sampling area, so as to achieve normal resolution compression of a local image and to ensure that the shape of the entire image, which is compressed, is identical to the shape of the original image (for example, the original image is a rectangular image, and the image, which is compressed, is also a rectangular image). 
     For example, a size of the original compression resolution sampling area, a size of the original resolution sampling area, the size of the first display area, and the size of the first sampling area are all identical. 
     For example, in some alternative implementations of this embodiment, the original resolution sampling area and the compression resolution sampling area form a nine-grid structure. For example, the original resolution sampling area is located in a middle grid of the nine-grid. Such a rule facilitates to adjust the center point position of the original resolution sampling area and the transverse resolution compression multiple and/or the longitudinal resolution compression multiple of the compression resolution sampling area. In addition, in this case, the original resolution sampling area corresponds to the gaze point more accurately. 
     For example, as shown in  FIG. 4B , in some examples, the rendering model  100  includes nine sampling sub-areas, and the nine sampling sub-areas are arranged in three rows and three columns, i.e., the original resolution sampling area and the compression resolution sampling area form a nine-grid structure, and the nine-grid structure includes nine sampling sub-areas arranged in three rows and three columns. The original resolution sampling area is located in the middle grid of the nine-grid, that is, the original resolution sampling area is located in a second row and a second column of the nine-grid structure. In the example shown in  FIG. 4B , the original resolution sampling area includes the sampling sub-area  105 , that is, the sampling sub-area  105  is the original resolution sampling area; and the compression resolution sampling area includes eight sampling sub-areas, namely, the compression resolution sampling area includes a sampling sub-area  101 , a sampling sub-area  102 , a sampling sub-area  103 , a sampling sub-area  104 , a sampling sub-area  106 , a sampling sub-area  107 , a sampling sub-area  108 , and a sampling sub-area  109 . 
     For example, each of the sampling sub-area  101 , the sampling sub-area  103 , the sampling sub-area  107 , and the sampling sub-area  109  may have a transverse resolution compression multiple and a longitudinal resolution compression multiple, that is, each of the sampling sub-area  101 , the sampling sub-area  103 , the sampling sub-area  107 , and the sampling sub-area  109  may be compressed in the first direction and the second direction. The sampling sub-area  102  and the sampling sub-area  108  may only have a longitudinal resolution compression multiple, that is, in the first direction, the sampling sub-area  102  and the sampling sub-area  108  may be compressed, while in the second direction, the sampling sub-area  102  and the sampling sub-area  108  are not compressed. The sampling sub-area  104  and the sampling sub-area  106  may only have a transverse resolution compression multiple, that is, in the first direction, the sampling sub-area  104  and the sampling sub-area  106  are not compressed, while in the second direction, the sampling sub-area  104  and the sampling sub-area  106  may be compressed. 
     For example, the longitudinal resolution compression multiple of the sampling sub-area  101 , the longitudinal resolution compression multiple of the sampling sub-area  102 , and the longitudinal resolution compression multiple of the sampling sub-area  103  are all identical. The longitudinal resolution compression multiple of the sampling sub-area  107 , the longitudinal resolution compression multiple of the sampling sub-area  108 , and the longitudinal resolution compression multiple of the sampling sub-area  109  are also identical. 
     For example, the transverse resolution compression multiple of the sampling sub-area  101 , the transverse resolution compression multiple of the sampling sub-area  104 , and the transverse resolution compression multiple of the sampling sub-area  107  are all identical. The transverse resolution compression multiple of the sampling sub-area  103 , the transverse resolution compression multiple of the sampling sub-area  106 , and the transverse resolution compression multiple of the sampling sub-area  109  are also identical. 
     For example, as shown in  FIG. 4A , the original rendering model  200  may include nine original sampling sub-areas, and the nine original sampling sub-areas are an original sampling sub-area  201 , an original sampling sub-area  202 , an original sampling sub-area  203 , an original sampling sub-area  204 , an original sampling sub-area  205 , an original sampling sub-area  206 , an original sampling sub-area  207 , an original sampling sub-area  108 , and an original sampling sub-area  209 . Moreover, the nine original sampling sub-areas are arranged in three rows and three columns, namely, the original original-resolution sampling area and the original compression resolution sampling area can also form a nine-grid structure, and the original original-resolution sampling area is located in a middle grid of the nine-grid, namely, the original original-resolution sampling area is an original sampling sub-area  205  located in a second row and the second column of the nine-grid. The original compression resolution sampling area includes eight original sampling sub-areas, namely, an original sampling sub-area  201 , an original sampling sub-area  202 , an original sampling sub-area  203 , an original sampling sub-area  204 , an original sampling sub-area  206 , an original sampling sub-area  207 , an original sampling sub-area  208 , and an original sampling sub-area  209 . 
     For example, the original sampling sub-areas of the original compression resolution sampling area are in one-to-one correspondence to the sampling sub-areas of the compression resolution sampling area. For example, the original sampling sub-area  201  located in a first column and a first row in the original compression resolution sampling area corresponds to the sampling sub-area  101  located in a first column and a first row in the compression resolution sampling area, the original sampling sub-area  202  located in a second column and a first row in the original compression resolution sampling area corresponds to the sampling sub-area  102  located in a second column and a first row in the compression resolution sampling area, and so on. 
     For example, the original original-resolution sampling area corresponds to the original resolution sampling area, and a size of the original original-resolution sampling area is identical to a size of the original resolution sampling area. That is, the original sampling sub-area  205  as shown in  FIG. 4A  corresponds to and is identical to the sampling sub-area  105  as shown in  FIG. 4B . 
     For example, a shape of the original original-resolution sampling area and a shape of the original resolution sampling area may both be rectangles. 
     For example, as shown in  FIG. 4A , a center of the original original-resolution sampling area  205  coincides with a center of the original rendering model. However, as shown in  FIG. 4B , the center of the original resolution sampling area  105  does not coincide with the center of the rendering model. 
     For example, in some alternative implementations of this embodiment, adjusting the center point position of the original resolution sampling area includes: 
     in a case where a center point of the original resolution sampling area is the gaze point position, judging whether the original resolution sampling area exceeds a boundary of the image to be displayed: 
     if not, adjusting the center point of the original resolution sampling area to be the gaze point position; 
     if yes, adjusting the center point of the original resolution sampling area to be a position closest to the gaze point position in a case where the original resolution sampling area does not exceed the boundary of the image to be displayed. 
     It should be noted that in the preset of the rendering model, the center point position of the original resolution sampling area corresponds to the center point position of the entire model. In a case where the center point position of the original resolution sampling area is adjusted to deviate from the center point position of the entire model according to the gaze point, the transverse and/or longitudinal resolution compression multiples of the compression resolution sampling area will be adjusted accordingly. 
       FIG. 5A  is a schematic diagram of a positional relationship between a gaze point position and an original resolution sampling area on an image to be displayed provided by some embodiments of the present disclosure;  FIG. 5B  is a schematic diagram of another positional relationship between a gaze point position and an original resolution sampling area provided by some embodiments of the present disclosure; and  FIG. 5C  is a schematic diagram of a center of an original resolution sampling area after being adjusted provided by some embodiments of the present disclosure. 
     For example, as shown in  FIG. 5A , in some examples, on the image to be displayed  20 , the gaze point position is shown as a point E. In a case where the center point of the original resolution sampling area  105  coincides with the gaze point position E, the original resolution sampling area  105  does not exceed the boundary of the image to be displayed  20 , at this time, the center point of the original resolution sampling area  105  is the gaze point position E. 
     It should be noted that in the embodiment of the present disclosure, the center of the original compression resolution sampling area of the original rendering model coincides with the center of the original rendering model, and the center of the original rendering model corresponds to the center of the image to be displayed. 
     For example, as shown in  FIG. 5A , the gaze point position E does not coincide with the center point C of the image to be displayed  20 , and relative to the center point C of the image to be displayed  20 , the gaze point position E is closer to a boundary on a right edge of the image to be displayed  20  and is closer to a boundary on a upper edge of the image to be displayed  20 . For example, in  FIG. 5A , the center of the original original-resolution sampling area  205  may be the center point C of the image to be displayed  20 , and the center of the original resolution sampling area  105  is the gaze point position E. In this case, three original sampling sub-areas located in the first row of the original rendering model are compressed in a longitudinal direction, three original sampling sub-areas located in a third row of the original rendering model are stretched in the longitudinal direction, three original sampling sub-areas located in a third column of the original rendering model are compressed in a transverse direction, and three original sampling sub-areas located in a first column of the original rendering model are stretched in the transverse direction. As shown in  FIG. 4B , the rendering model can be obtained after the above adjustments are performed on the original rendering model. For example, the original sampling sub-area  201  as shown in  FIG. 4A  is compressed in the first direction and stretched in the second direction, so that the sampling sub-area  101  as shown in  FIG. 4B  can be obtained, that is, in the first direction, a length of the original sampling sub-area  201  is less than a length of the sampling sub-area  101 , while in the second direction, a length of the original sampling sub-area  201  is larger than a length of the sampling sub-area  101 . At this time, the rendering model can still include nine sampling sub-areas. 
     For example, in the example shown in  FIG. 5A , the first sampling area of the image to be displayed  20  is the sampling sub-area  105 , so that the center point of the first sampling area  105  is the gaze point position E. 
     It is worth noting that the rendering model may only include four or six sampling sub-areas. 
     For example, as shown in  FIG. 5B , in other examples, on the image to be displayed  20 , the gaze point position is indicated by a point C. In a case where the center point of the original resolution sampling area  105  coincides with the gaze point position E, the original resolution sampling area  105  exceeds the boundary of the image to be displayed  20 , for example, the original resolution sampling area  105  exceeds the boundary of the right edge and the boundary of the lower edge of the image to be displayed  20 , that is, the gaze point position E is located at a right lower corner of the image to be displayed  20  with respect to the center point C of the image to be displayed  20 . In this case, it is necessary to adjust the center point of the original resolution sampling area  105 . In a case where the original resolution sampling area  105  does not exceed the boundary of the image to be displayed  20 , the position closest to the gaze point position E is the center point of the original resolution sampling area  105 . For example, as shown in  FIG. 5C , in a case where two adjacent edges of the original resolution sampling area  105  respectively coincide with two adjacent edges (i.e., an edge of the right edge and an edge of the lower edge) of the image to be displayed  20 , the position of the center point of the original resolution sampling area  105  is the position closest to the gaze point position E in a case where the original resolution sampling area  105  does not exceed the boundary of the image to be displayed  20 . 
     For example, in  FIG. 5C , two adjacent edges of the original resolution sampling area  105  respectively coincide with two adjacent edges of the image to be displayed  20 , i.e., the first sampling area corresponding to the original resolution sampling area  105  may be located in a corner (lower right corner) of the rectangle. At this time, the rendering model may include four sampling sub-areas, that is, an area of the sampling sub-area  103 , an area of the sampling sub-area  107 , an area of the sampling sub-area  108 , and an area of the sampling sub-area  109  as shown in  FIG. 4B  are all zero. In this case, two original sampling sub-areas (i.e., the original sampling sub-area  201  and the original sampling sub-area  202  as shown in  FIG. 4A ) located in the first row and the first column and in the first row and the second column in the original rendering model are stretched in the longitudinal direction (i.e., the first direction). Two original sampling sub-areas (i.e., the original sampling sub-area  201  and the original sampling sub-area  204  as shown in  FIG. 4A ) located in the first row and the first column and in the second row and the first column in the original rendering model are stretched in the transverse direction, and the rendering model can be obtained after performing the above-mentioned adjustment on the original rendering model. 
     It should be noted that in a case where the rendering model includes nine sampling sub-areas, a total area of the nine sampling sub-areas is SW, and in a case where the rendering model includes four sampling sub-areas, a total area of the four sampling sub-areas is also SW, that is, the size of the rendering model does not change with an amount of sampling sub-areas. 
     At least some embodiments of the present disclosure also provide an image display method.  FIG. 6  is a schematic flowchart of an image display method provided by some embodiments of the present disclosure. As shown in  FIG. 6 , the image display method may include the following steps: 
     S 60 : acquiring an image to be displayed; 
     S 61 : according to a gaze point of human eyes on a display screen of a virtual reality device, obtaining a gaze point position, which corresponds to the gaze point, on the image to be displayed; 
     S 62 : determining, according to the gaze point position, a first sampling area and a second sampling area of the image to be displayed; 
     S 63 : performing first resolution sampling on the first sampling area to obtain a first display area; 
     S 64 : performing second resolution sampling on the image to be displayed to obtain a second display area corresponding to the second sampling area, where a resolution of the second sampling area is greater than a resolution of the second display area; 
     S 65 : splicing the first display area and the second display area to obtain an output image; 
     S 66 : transmitting the output image to the virtual reality device; 
     S 67 : stretching the output image by the virtual reality device to obtain a stretched image; and 
     S 68 : displaying the stretched image on the display screen of the virtual reality device. 
     For example, the above steps S 60  to S 66  are all implemented in a rendering engine, and steps S 67  to S 68  are implemented in a virtual reality device. Therefore, the image display method provided by the embodiment of the present disclosure can achieve image compression rendering at the rendering engine terminal, then the output image, which is compressed, is transmitted to the virtual reality device, and then the virtual reality device displays the output image, which is compressed, thereby reducing the transmission bandwidth output by the software terminal to the display device, saving the transmission bandwidth during the image transmission process, achieving real-time sampling and transmission of images, and meeting the requirement of real-time processing of a large amount of data in the virtual reality technology. 
     For example, in the image display method, the detailed description of respective steps S 60 -S 66  performed in the rendering engine may refer to the description of the image rendering method in the above embodiment. For example, the detailed description of step S 60  may refer to the description of step S 10 , the detailed description of step S 61  may refer to the description of step S 11 , the detailed description of step S 62  may refer to the description of step S 12 , the detailed description of step S 63  may refer to the description of step S 13 , the detailed description of step S 64  may refer to the description of step S 14 , and the detailed description of steps S 65  and S 66  may refer to the description of step S 15 . 
     For example, the display screen may include a liquid crystal display panel or the like. 
     For example, the output image includes the first display area and the second display area, and step S 67  includes: stretching the second display area in the output image by the virtual reality device to obtain a stretched display area; and determining the stretched image according to the first display area and the stretched display area. That is, a size of the stretched display area is larger than the size of the second display area, and the stretched image is obtained by splicing the first display area and the stretched display area, that is, the stretched image includes the stretched display area and the first display area. 
     For example, in some alternative implementations of this embodiment, in step S 67 , the received output image is stretched by an integrated circuit (IC) using the virtual reality device to obtain the stretched image, and then the stretched image is displayed on the display screen. 
     For example, the size of the stretched image may be identical to the size of the image to be displayed. For example, a stretching multiple of each sub-area in the second display area is identical to the compression multiple of each sub-area in the second sampling area. For example, in the example shown in  FIG. 2A , for the sub-area to be displayed  1 , the sub-area to be displayed  1  corresponds to the output sub-area  11  in the output image  30 . In a case where the sub-area to be displayed  1  is compressed by a proportion  1 /F 1  in the first direction, the sub-area to be displayed  1  is compressed by a proportion  1 /F 2  in the second direction, that is, in the first direction, the sub-area to be displayed  1  is reduced by F 1  times, and in the second direction, the sub-area to be displayed  1  is reduced by F 2  times. Then in the stretching process, the output sub-area  11  needs to be stretched by a proportion F 1  in the first direction, and the output sub-area  11  needs to be stretched by a proportion F 2  in the second direction, that is, in the first direction, the output sub-area  11  is expanded by F 1  times, and in the second direction, the output sub-area  11  is expanded by F 2  times. The processing method of the remaining output sub-areas in the output image is similar to the processing method of the output sub-area  11  and will not be described in detail herein again. 
     For example, F 1  and F 2  are both greater than 1. According to actual requirements, F 1  and F 2  can be the same or different, and there is no restriction on F 1  and F 2 . 
     A specific scene is substituted to further explain the image rendering method and the image display method for virtual reality provided by this embodiment below. 
     In a scene, the display screen may be a display screen of a VR (Virtual Reality)/AR (Augmented Reality) head-mounted display device, and a transmission process of the image (i.e., output image) occurs between the computer device and the VR/AR head-mounted display device. 
     Due to the limitation of transmission bandwidth, the computer device directly transmits 4K images to the VR/AR head-mounted display device, which puts too much pressure on hardware to complete real-time display with high resolution and high refresh rate. According to the observation definition of human eye and the implementation of human eye tracking technology, non-high-definition areas of the 4K images can be compressed to save the transmission bandwidth. 
     For example, as shown in  FIG. 2A , for a high-resolution image to be displayed  20 , the image to be displayed  20  is divided into nine sub-areas to be displayed according to the form of a nine-grid, the sub-area to be displayed  5  is the original resolution sampling area (high definition area) corresponding to the gaze point. The other eight sub-areas to be displayed are respectively processed as follows: the transverse resolutions and the longitudinal resolutions of the sub-area to be displayed  1 , the sub-area to be displayed  3 , the sub-area to be displayed  7 , and the sub-area to be displayed  9  are simultaneously compressed by 4 times; the transverse resolutions of the sub-area to be displayed  2  and the sub-area to be displayed  8  are unchanged, and the longitudinal resolutions of the sub-area to be displayed  2  and the sub-area to be displayed  8  are compressed by 4 times. The longitudinal resolutions of the sub-area to be displayed  4  and the sub-area to be displayed  6  are unchanged, and the transverse resolution of the sub-area to be displayed  4  and the sub-area to be displayed  6  are compressed by 4 times. The resolution size of the image to be displayed  20  is 4320*4800, and the resolution size of the output image  30 , which is compressed, is 2160*2400. Compared with the image to be displayed  20 , the transverse resolution of the output image  30 , which is compressed, is 50% of the transverse resolution of the original image to be displayed  20 , and the longitudinal resolution of the output image  30 , which is compressed, is 50% of the longitudinal resolution of the original image to be displayed  20 , thus saving 75% of the bandwidth in the process of transmitting the output image  30 . In a case where the gaze point position changes, the range and position of the original resolution sampling area (i.e. the sub-area to be displayed  5 ) and the ranges and sizes of the other eight sub-areas to be displayed (the size here corresponds to the resolution) are adjusted accordingly, and the correct compression output result can be completed. 
     As shown in  FIG. 3 , in the process of performing the image rendering method for virtual reality provided by the embodiment of the present disclosure: Step 1  is to perform a whole sampling on the scene to obtain the original image  15 , the resolution of the original image  15  is 4320*4800. Step 2  is to perform inverse-distortion processing on the original image  15  obtained in Step 1  to obtain an image to be displayed  20 , and the resolution of the image to be displayed  20  is also  4320 * 4800 . For example, the image to be displayed  20  includes a first sampling area and a second sampling area, and the first sampling area is an area corresponding to the gaze point position. Step 3  is to perform sampling on the inverse-distortion result (i.e. the image to be displayed  20 ). In Step 3 , according to the rendering model, the original resolution (high-definition resolution) sampling is performed on the high-definition area (i.e. the first sampling area) of the image to be displayed  20  to obtain an image  25  corresponding to the first display area. The resolution of the image  25 , which is sampled, is 1440*1600. In Step 3 , according to the rendering model, compression resolution (low resolution) sampling is performed on the entire image to be displayed  20  to obtain an intermediate image to be displayed  26 , and the resolution of the intermediate image to be displayed  26 , which is sampled, is 1080*1200. Then, the intermediate image to be displayed is divided according to the positional relationship between the first sampling area and the second sampling area and the proportional relationship between the first sampling area and the second sampling area to obtain a second intermediate display area corresponding to the second sampling area, and the second display area includes the second intermediate display area. It should be noted that the reason why the compression resolution (low resolution) sampling is performed on the entire image to be displayed  20  instead of on the second sampling area is convenient to implement. In fact, in some examples, only the second sampling area may be sampled. Step 4  is to splice the high-definition area (i.e., the first display image) and the non-high-definition area (i.e., the second display area), to obtain the output image  30 , and the resolution of the output image  30  is 2160*2400. For example, Step 4  may include: determining a rendering model, which includes an original resolution sampling area and a compression resolution sampling area, according to the gaze point position; and placing the first display area at a position corresponding to the original resolution sampling area and placing the second display area at a position corresponding to the compression resolution sampling area to obtain the output image  30 . Step 5  is to stretch the output image  30  by the VR/AR head-mounted display device to obtain a stretched image  35 , and the resolution of the stretched image  35  is 4320*4800. 
     For example, as shown in  FIG. 4A , an original rendering model (multi-resolution) created by the modeling software is used to establish an original rendering model  200  according to a situation that the gaze point is in the center, and the original rendering model  200  includes a plurality of original sampling sub-areas; and then, a reference position of each original sampling sub-area in the original rendering model  200  is adjusted (in order to facilitate the change of the model shape). It should be noted that the reference position of each original sampling sub-area here is a point at which the position does not change during performing compression. 
     For example, a reference position of the original sampling sub-area  201  is a left upper corner of the original sampling sub-area  201 , i.e., a point Q 1 . In a case where the original rendering model starts to change, only the size of the original sampling sub-area  201  is modified, and there is no need to modify the reference position of the original sampling sub-area  201 . The original sampling sub-areas  203 ,  207  and  209  are similarly processed, that is, a reference position of the original sampling sub-area  203  is a right upper corner of the original sampling sub-area  203 , namely a point Q 3 , a reference position of the original sampling sub-area  207  is a left lower corner of the original sampling sub-area  207 , namely a point Q 7 , and a reference position of the original sampling sub-area  209  is a right lower corner of the original sampling sub-area  209 , namely a point Q 9 . A reference position of the original sampling sub-area  202  is located in an upper edge of the original sampling sub-area  202 , for example, a midpoint of the upper edge, i.e., a point Q 2 ; a reference position of the original sampling sub-area  208  is located in a lower edge of the original sampling sub-area  208 , e.g., a midpoint of the lower edge, i.e., a point Q 8 . For the original sampling sub-areas  202  and  208 , in a case where the original rendering model changes, only an abscissa of the point Q 2  and an abscissa of the point Q 8  need to be modified while an ordinate of the point Q 2  and an ordinate of the point Q 8  are unchanged. A reference position of the original sampling sub-area  204  may be placed at a left edge of the original sampling sub-area  204 , such as a midpoint of the left edge, i.e., a point Q 4 , and a reference position of the original sampling sub-area  206  may be placed at a right edge of the original sampling sub-area  206 , such as the midpoint of the right edge, i.e., a point Q 6 . In a case where the original rendering model changes, an ordinate of the points Q 4  and an ordinate of Q 6  are modified, while an abscissa of the points Q 4  and an abscissa of Q 6  remain unchanged. A reference position of the original sampling sub-area  205  is still at a very center of the original sampling sub-area  205 , i.e., a point Q 5 . In a case where the original rendering model changes, the original sampling sub-area  205  will not change in size, and only an abscissa and an ordinate of the point Q 5  are modified. 
     For example, the original rendering model is located in a Cartesian coordinate system x-o-y, and a coordinate origin o of the Cartesian coordinate system x-o-y coincides with the point Q 5 . 
     For example, in the Cartesian coordinate system x-o-y, the abscissas of points Q 1 , Q 4 , and Q 7  are the same, the abscissas of points Q 2 , Q 5 , and Q 8  are the same, and the abscissas of points Q 3 , Q 6 , and Q 9  are the same. The ordinates of points Q 1 , Q 2 , and Q 3  are the same, the ordinates of points Q 4 , Q 5 , and Q 6  are the same, and the ordinates of points Q 7 , Q 8 , and Q 9  are the same. 
     For example, as shown in  FIG. 4B , in some examples, the rendering model  100  is obtained after adjusting the original rendering model  200 . The rendering model  100  includes a plurality of sampling sub-areas, and the plurality of sampling sub-areas are in one-to-one correspondence to the plurality of original sampling sub-areas shown in  FIG. 4A . 
     For example, a reference position of the sampling sub-area  101  is a left upper corner of the sampling sub-area  101 , that is, a point P 1 . In the Cartesian coordinate system x-o-y, a coordinate of the point P 1  is the same as a coordinate of the reference position Q 1  of the original sampling sub-area  201 , while the size of the sampling sub-area  101  is different from the size of the original sampling sub-area  201 . Sampling sub-areas  103 ,  107 , and  109  are also similar to the sampling sub-area  101 , that is, a reference position of the sampling sub-area  103  is a right upper corner of the sampling sub-area  103 , i.e., a point P 3 , a reference position of the sampling sub-area  107  is a left lower corner of the sampling sub-area  107 , i.e., a point P 7 , and a reference position of the sampling sub-area  109  is a right lower corner of the sampling sub-area  109 , i.e., a point P 9 . 
     For example, a reference position of the sampling sub-area  102  is located in an upper edge of the sampling sub-area  102 , such as a midpoint of the upper edge, i.e., a point P 2 , and a reference position of the sampling sub-area  108  is located in a lower edge of the sampling sub-area  108 , such as a midpoint of the lower edge, i.e., a point P 8 . In the Cartesian coordinate system x-o-y, an ordinate of the point P 2  is the same as the ordinate of the reference position Q 2  of the original sampling sub-area  202 , while an abscissa of the point P 2  is different from the abscissa of the reference position Q 2  of the original sampling sub-area  202 ; and similarly, an ordinate of the point P 8  is the same as the ordinate of the reference position Q 8  of the original sampling sub-area  208 , while an abscissa of the point P 8  is different from the abscissa of the reference position Q 8  of the original sampling sub-area  208 . 
     For example, a reference position of the sampling sub-area  104  may be located in a left edge of the sampling sub-area  104 , such as a midpoint of the left edge, i.e., a point P 4 , and a reference position of the sampling sub-area  106  may be located in a right edge of the sampling sub-area  106 , such as a midpoint of the right edge, i.e., a point P 6 . In the Cartesian coordinate system x-o-y, an abscissa of the point P 4  is the same as the abscissa of the reference position Q 4  of the original sampling sub-area  204 , while an ordinate of the point P 4  is different from the ordinate of the reference position Q 4  of the original sampling sub-area  204 ; and similarly, an abscissa of the point P 6  is the same as the abscissa of the reference position Q 6  of the original sampling sub-area  206 , while an ordinate of the point P 6  is different from the ordinate of the reference position Q 6  of the original sampling sub-area  206 . 
     For example, a reference position of the sampling sub-area  105  is located in a center of the sampling sub-area  105 , that is, a point P 5 . In the Cartesian coordinate system x-o-y, an abscissa of the point P 5  is different from the abscissa of the reference position Q 5  of the original sampling sub-area  205 , and an ordinate of the point P 5  is also different from the ordinate of the reference position Q 5  of the original sampling sub-area  205 . The sampling sub-area  105  has the same size as the original sampling sub-area  205 . As shown in  FIG. 4B , the reference position P 5  of the sampling sub-area  105  does not coincide with the coordinate origin o of the Cartesian coordinate system x-o-y. 
     For example, in the Cartesian coordinate system x-o-y, the abscissas of points P 1 , P 4 , and P 7  are the same, the abscissas of points P 2 , P 5 , and P 8  are the same, and the abscissas of points P 3 , P 6 , and P 9  are the same. The ordinates of points P 1 , P 2 , and P 3  are the same, the ordinates of points P 4 , P 5 , and P 6  are the same, and the ordinates of points P 7 , P 8 , and P 9  are the same. 
       FIG. 7  is a schematic diagram of rendering models and output images corresponding to different gaze point positions provided by some embodiments of the present disclosure. 
     For example, as shown in  FIG. 7 , the position, where the gaze point can fall, is projected into a two-dimensional coordinate systems x′-o′-y′ which is from (−1, −1) to (1,1). For example, an area bounded by a center point of the sub-area to be displayed  1 , a center point of the sub-area to be displayed  3 , a center point of the sub-area to be displayed  7 , and a center point of the sub-area to be displayed  9  in the image to be displayed  20  as shown in  FIG. 2A  is the position where the gaze point can fall. In the two-dimensional coordinate system x′-o′-y′, a coordinate of the center point of the sub-area to be displayed  1  is (−1,1), a coordinate of the center point of the sub-area to be displayed  2  is (0,1), a coordinate of the center point of the sub-area to be displayed  3  is (1,1), a coordinate of the center point of the sub-area to be displayed  4  is (−1,0), a coordinate of the center point of the sub-area to be displayed  5  is (0,0), and a coordinate of the center point of the sub-area to be displayed  6  is (1,0), a coordinate of the center point of the sub-area to be displayed  7  is (−1, −1), a coordinate of the center point of the sub-area to be displayed  8  is (0, −1), and a coordinate of the center point of the sub-area to be displayed  9  is (1, −1). 
     For example, gaze point positions corresponding to four cases (i.e., Pic 1 , Pic 2 , Pic 3 , and Pic 4 ) as shown in  FIG. 7  are (0, 0), (0.5, 0.5), (1, 1) (areas of the sampling sub-areas  101 ,  102 ,  103 ,  106 ,  109  are 0), (1, 0) (areas of the sampling sub-areas  103 ,  106 ,  109  are 0) in the two-dimensional coordinate system x′-o′-y′, respectively. In a case where the gaze point position changes, area sizes and corresponding ranges of the original sampling sub-areas  201 ,  203 ,  207 ,  209  are modified according to the gaze point position, while reference positions of the original sampling sub-areas  201 ,  203 ,  207 ,  209  do not need to be modified; the abscissas of the reference positions, the area sizes in the longitudinal direction, and the corresponding ranges of the original sampling sub-areas  202 ,  208  are modified according to the gaze point position; and the ordinates of the reference positions, the area sizes in the transverse direction, and the corresponding ranges of the original sampling sub-areas  204 ,  206  are modified according to the gaze point position. The abscissa and ordinate of the reference position of the original sampling area  205  are modified according to the gaze point position, and meanwhile, the position of the virtual camera is adjusted, thereby obtaining an inverse-distortion image of the high definition area. 
     For example, the sampling sub-area  101  is obtained by adjusting the original sampling sub-area  201 , and the calculation result of the sampling sub-area  101  is as follows. 
     Assume that the coordinate of the gaze point position in the two-dimensional coordinate system x′-o′-y′ is (x,y)(x∈[−1,1], y∈[−1,1]). 
     Then the size of the sampling sub-area  101  is: localScale=(x+1, 1−y). For example, in some examples, in a case where the original sampling sub-area  201  and the sampling sub-area  101  are rectangles, and a first edge of the original sampling sub-area  201  is T 1 , a second edge of the original sampling sub-area  201  is T 2 , and the first edge and the second edge are two adjacent edges of the original sampling sub-area  201 , the first edge represents an edge in the first direction and the second edge represents an edge in the second direction. The sampling sub-area  101  includes a third edge and a fourth edge, the third edge of the sampling sub-area  101  corresponds to the first edge of the original sampling sub-area  201 , and the fourth edge of the sampling sub-area  101  corresponds to the second edge of the original sampling sub-area  201 , then the third edge is represented as T 1 *(1−y), and the fourth edge is represented as T 2 *(x+1). 
     For example, a pasting image area corresponding to the sampling sub-area  101  is:
 
mainTextureScale=(( x+ 1)/3,(1− y )/3)
 
mainTextureOffset=(0,( y+ 2)/3).
 
     For example, in some examples, the shape of the rendering model may be a rectangle, the rendering model can be located in a two-dimensional coordinate system x″-o″-y″, a left lower corner of the rendering model is located at a coordinate origin of the two-dimensional coordinate system x″-o″-y″, and the rendering model is projected to an area from (−1, −1) to (1, 1). A length of the rendering model is R 1  in an x″ axis direction, and a length of the rendering model is R 2  in a y″ axis direction. In the x″ axis direction, a length of the sampling sub-area  101  is R 1 *(x+1)/3, and in the y″ axis direction, a length of the sampling sub-area  101  is R 2 *(1−y)/3. A coordinate of the left lower corner of the sampling sub-area  101  in the two-dimensional coordinate system x″-o″-y″ is (0, (y+2)/3). 
     The area sizes, reference positions and ranges of the other sampling sub-areas are also calculated by a similar method. For example, the size of the sampling sub-area  102  is: localScale=(1, 1−y), and a pasting image area corresponding to the sampling sub-area  102  is:
 
mainTextureScale=(1/3,(1− y )/3)
 
mainTextureOffset=(1/3,( y+ 2)/3).
 
     In a case where the gaze point position changes, the value of x and the value of y are changed, and the corresponding rendering model changes, thus generating an output image matching the current gaze point position. 
       FIG. 8  shows a structural schematic diagram of an image rendering device for virtual reality provided by at least some embodiments of the present disclosure. As shown in  FIG. 8 , other embodiments of the present disclosure provide an image rendering device for virtual reality, and the image rendering device includes a gaze point projection module, an adjustment module, a rendering engine, and a splicing module. 
     For example, the gaze point projection module is configure to obtain, according to a gaze point of human eyes on a display screen of a virtual reality device, a gaze point position, which corresponds to the gaze point, on the image to be displayed. 
     For example, the rendering engine is configure to: determine, according to the gaze point position, a first sampling area and a second sampling area of the image to be displayed; perform first resolution sampling on the first sampling area to obtain a first display area; perform second resolution sampling on the image to be displayed to obtain a second display area corresponding to the second sampling area. For example, a resolution of the second sampling area is greater than a resolution of the second display area. 
     For example, as shown in  FIG. 8 , the rendering engine includes a virtual camera and a rendering model, and the virtual camera is configured to perform first resolution sampling on the first sampling area and perform second resolution sampling on the image to be displayed according to the rendering model. 
     For example, in some examples, the rendering engine may be further configured to load the rendering model, i.e., determine the rendering model, according to the gaze point position, the rendering model includes an original resolution sampling area, a compression resolution sampling area, and a resolution compression multiple of the compression resolution sampling area; the original resolution sampling area corresponds to the first sampling area, and the compression resolution sampling area corresponds to the second sampling area. 
     For example, the rendering engine is further configured to acquire an original rendering model, and the original rendering model includes an original original-resolution sampling area and an original compression resolution sampling area. 
     For example, the adjustment module is configured to, according to the gaze point position, adjust a center point position of the original original-resolution sampling area and a resolution compression multiple of the original compression resolution sampling area to determine the rendering model. 
     For example, the splicing module is configured to splice the first display area and the second display area to obtain an output image to be transmitted to the virtual reality device. 
     It should be noted that the components of the image rendering device as shown in  FIG. 8  are only exemplary and not limiting, and the image rendering device may also have other components according to actual application needs. 
     It should be noted that the principle and the working process of the image rendering device for virtual reality provided in this embodiment are similar to the above-mentioned image rendering method for virtual reality, for the relevant points, reference may be made to the above description, and details are not repeated herein again. 
       FIG. 9  shows a schematic diagram of an image rendering system for virtual reality provided by at least some embodiments of the present disclosure. 
     For example, other embodiments of the present disclosure provide an image rendering system for virtual reality, and the image rendering system includes a virtual reality device and an image rendering device. The image rendering device include a gaze point projection module, an adjustment module, a rendering engine, and a splicing module. 
     The gaze point projection module is configure to obtain, according to a gaze point position of human eyes on a display screen of a virtual reality device, a position, which corresponds to the gaze point, on the image to be displayed on the display screen. 
     The rendering engine is configure to load a rendering model, and the rendering model is preset with an original resolution sampling area, a compression resolution sampling area and a transverse resolution compression multiple and/or a longitudinal resolution compression multiple of the compression resolution sampling area. 
     The adjustment module is configured to adjust a center point position of the original resolution sampling area and the transverse resolution compression multiple and/or the longitudinal resolution compression multiple of the compression resolution sampling area according to the position, which corresponds to the gaze point, on the image to be displayed on the display screen. 
     The rendering engine is configured to perform original resolution sampling on the original resolution sampling area of the image and perform compression resolution sampling on the compression resolution sampling area according to the rendering model which is adjusted. 
     The splicing module is configured to splice the original resolution sampling area, which is sampled, and the compression resolution sampling area, which is sampled, to obtain the image to be transmitted to the virtual reality device. 
     For example, as shown in  FIG. 9 , other embodiments of the present disclosure also provide an image rendering system for virtual reality, and the image rendering system includes a virtual reality device and an image rendering device. The image rendering device is the image rendering device according to any one of the above embodiments of the present disclosure. 
     For example, the virtual reality device may be a head-mounted display device or the like. The head-mounted display device is used for acquiring the gaze point of human eyes on the display screen of the virtual reality device and receiving the output image transmitted by the image rendering device. 
     For example, the virtual reality device is also configured to acquire an original image of a scene. The virtual reality device or the image rendering device can perform inverse-distortion processing on the original image to obtain an image to be displayed. 
     It should be noted that the principle and the working process of the image rendering system for virtual reality provided in this embodiment are similar to the above-mentioned image rendering method for virtual reality, for the relevant points, reference can be made to the above description, and details will not be repeated herein again. 
       FIG. 10  shows a structural schematic diagram of a computer device provided by at least some embodiments of the present disclosure. Another embodiment of the present disclosure provides a computer device. 
     For example, a computer device includes a memory and a processor. For example, the memory is configured to store a computer program. The processor is configured to execute the computer program. In a case where the computer program is executed by the processor, one or more steps in the image rendering method described in any one of the above embodiments are implemented. 
     For example, the processor may be a central processing unit (CPU) or other form of processing unit having data processing capability and/or program execution capability, such as a field programmable gate array (FPGA) or tensor processing unit (TPU), etc. 
     For example, the memory may include any combination of one or more computer program products, which may include various forms of computer readable storage media, such as volatile memory and/or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and/or cache, etc. The non-volatile memory may include, for example, read only memory (ROM), hard disk, erasable programmable read only memory (EPROM), portable compact disk read only memory (CD-ROM), USB memory, flash memory, and the like. One or more computer instructions may be stored on the memory, and the processor may execute the computer instructions to implement various functions. Various application programs and various data as well as various data used and/or generated by the application programs may also be stored in the computer readable storage medium. 
     For example, as shown in  FIG. 10 , in some examples, the computer device includes a central processing unit (CPU) that can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) or a program loaded from a storage portion into a random access memory (RAM). In the RAM, various programs and data required for the operation of the computer system are also stored. CPU, ROM, and RAM are connected with each other by bus. An input/output (I/O) interface is also connected to the bus. 
     The following components are connected to the I/O interface: an input portion including a keyboard, a mouse, etc.; an output portion including such as a liquid crystal display (LCD) or the like and a speaker or the like; a storage portion including a hard disk or the like; and a communication portion including a network interface card such as a LAN card, a modem, etc. The communication portion performs communication processing via a network such as the Internet. A driver is also connected to I/O interfaces as needed. Removable media, such as magnetic disks, optical disks, magneto-optical disks, semiconductor memories, etc., are installed on the driver as needed so that computer programs read from the driver can be installed into the storage portion as needed. 
     For example, according to the present embodiment, the process described in the flowchart above may be implemented as a computer software program. For example, the embodiment includes a computer program product including a computer program tangibly embodied on a computer readable medium, the above computer program includes program code for performing the method as shown in the flowchart. In such embodiments, the computer program may be downloaded and installed from the network through the communication portion and/or be installed from the removable medium. 
     The flowcharts and schematic diagrams in the drawings illustrate the architecture, functions, and operations of possible implementations of the system, method and computer program product of this embodiment. In this regard, each block in the flowchart or schematic diagram may represent a module, program segment, or a part of code, the above module, program segment, or a part of code contain one or more executable instructions for implementing specified logical functions. It should also be noted that in some alternative implementations, the functions noted in the blocks may also occur in an order different than that noted in the figures. For example, two blocks shown in a succession may actually be performed substantially in parallel, and the two blocks may sometimes be performed in the reverse order, which is depends on the functions involved. It should also be noted that each block in the schematic diagrams and/or flowchart, and combinations of blocks in the schematic diagrams and/or flowchart, can be implemented by dedicated hardware-based systems that perform specified functions or operations, or can be implemented by combinations of dedicated hardware and computer instructions. 
     The units described in this embodiment may be implemented by software or hardware. The described unit can also be placed in the processor, for example, it can be described as a processor including a gaze point projection module, an adjustment module, a rendering engine, and a splicing module. The names of these units do not constitute a limitation on the unit itself under certain circumstances. For example, the gaze point projection module can also be described as “an image gaze point acquisition module”. 
     Some embodiments of the present disclosure also provide a non-volatile computer storage medium, the non-volatile computer storage medium may be the non-volatile computer storage medium included in the above-mentioned computer devices in the above-mentioned embodiments, or may be a non-volatile computer storage medium that exists separately and not assembled in the terminal. The non-volatile computer storage medium stores one or more programs, and in a case where the one or more programs are executed by a device, the image rendering method described in any one of the above embodiments can be implemented. 
     In the description of the present disclosure, it should be noted that the orientation or positional relationship indicated by the terms “up”, “down”, and the like is based on the orientation or positional relationship shown in the drawings, and is only for convenience of describing the present disclosure and simplifying the description, and does not indicate or imply that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present disclosure. Unless otherwise expressly specified and defined, the terms “installed”, “connect”, and “connected” shall be broadly understood, for example, it may be fixed connection, removable connection, or integral connection; and it can be mechanical connection or electrical connection, and it can be direct connection, can also be indirect connection through an intermediate medium, can be the internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this disclosure can be understood according to specific situations. 
     It should also be noted that in the description of the present disclosure, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms “include”, “comprising” or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or device, that comprises a series of elements, does not include only those elements but also other elements not expressly listed or elements that are inherent to such process, method, article, or device. Without further limitation, an element defined by the statement “includes a . . . ” does not exclude the presence of another identical element in a process, method, article or device that includes the element. 
     Obviously, the above-mentioned embodiments of the present disclosure are merely examples for clearly explaining the present disclosure, and are not intended to limit the embodiments of the present disclosure. For those of ordinary skill in the art, other variations or modifications of different forms can be made on the basis of the above description. It is not possible to exhaustively list all the embodiments here, and any obvious changes or variations that belong to the technical scheme of the present disclosure are still within the protection scope of the present disclosure.