Field of view angle measurement method and device, computer device and medium

Abstract

Embodiments of the present application disclose a field of view angle measurement method and device, computer equipment and a medium. In a specific embodiment, the method comprises: controlling an extended reality display device to display a test picture; controlling an image acquisition device to acquire an image containing the test picture at a preset position; and calculating a field of view angle of the extended reality display device according to a lens field of view angle of the image acquisition device, a size ratio of a lens field of view of the image acquisition device to an acquisition field of view, and a size ratio of a test picture area contained in the image to the image. The size ratio of the lens field of view of the image acquisition device to the acquisition field of view is obtained through pre-calibration. According to the embodiment, the field of view angle of the extended reality display device can be quickly and accurately obtained through simple visual shooting, simple image processing and calculation, the rapid detection of the extended reality display device can be realized, and the embodiment is suitable for batch production of the extended reality display device.

Description

Technical Field

[0001] This invention relates to the field of optical inspection. More specifically, it relates to a method and apparatus for measuring field of view, a computer device, and a medium. Background Technology

[0002] Extended Reality (XR) encompasses Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR). In the development of devices such as head-mounted AR / VR headsets, display and optics are the key components determining device performance. Displays project visual images for human perception, aiming to provide a good visual experience. However, if the visual display system has imaging defects, it can lead to visual fatigue and dizziness in practical applications. The field of view (FOV) in extended reality is defined as the angle between the edge of the displayed image and the line connecting it to the user's eye. The size of the FOV directly determines the user's sense of immersion; therefore, the FOV of extended reality display devices must be consistent to ensure a good user experience. Summary of the Invention

[0003] The purpose of this invention is to provide a method and apparatus for measuring field of view, a computer device and a medium, to solve at least one of the problems existing in the prior art.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] The first aspect of the present invention provides a method for measuring the field of view of an extended reality display device, comprising:

[0006] Control the extended reality display device to display the test screen;

[0007] Control the image acquisition device to acquire images containing the test scene at a preset position; and

[0008] The field of view of the extended reality display device is calculated based on the lens field of view of the image acquisition device, the size ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the size ratio of the test screen area contained in the image to the image. The lens field of view of the image acquisition device and the size ratio of the lens field of view of the image acquisition device to the acquisition field of view are obtained through pre-calibration.

[0009] Optionally, calculating the field of view of the extended reality display device based on the lens field of view of the image acquisition device, the size ratio of the lens field of view to the acquisition field of view of the image acquisition device, and the size ratio of the test screen area contained in the image to the image itself includes calculating the field of view of the extended reality display device according to the following formula:

[0010] tanθ=(OC / OA)*(tanM) / m

[0011] Wherein, θ is the field of view of the extended reality display device; M is the lens field of view of the image acquisition device; m is the size ratio of the lens field of view of the image acquisition device to the acquisition field of view and the size ratio of the image to the test screen area contained in the image; (OC / OA) is the size ratio of the test screen area contained in the image to the image.

[0012] Optionally, the preset position is the center position at a preset distance from the display screen of the extended reality display device.

[0013] Optionally, the size ratio of the lens field of view to the acquisition field of view of the image acquisition device is m = OB / OA`, where OB is the radius of the lens field of view of the image acquisition device, OA` is the distance from the center to the first position point of the edge of the acquisition field of view of the image acquisition device, OC is the radius of the test screen area contained in the image, and OA is the distance from the center to the edge of the image, wherein the spatial position relationship between the first position point and the second position point corresponds.

[0014] Optionally, the test screen is a solid color screen, and the background of the image captured by the control image acquisition device at a preset position, which includes the test screen, is a solid color background that is different from the color of the solid color screen.

[0015] Optionally, controlling the image acquisition device to acquire an image containing the test screen at a preset position includes: controlling the image acquisition device to acquire an image containing the test screen at a preset position with an acquisition angle where the imaging surface is parallel to the display screen of the extended reality display device.

[0016] A second aspect of the present invention provides a field-of-view measurement device for an extended reality display device, comprising:

[0017] The first control module is used to control the extended reality display device to display the test screen;

[0018] The second control module is used to control the image acquisition device to acquire images containing the test screen at a preset position; and

[0019] The calculation module is used to calculate the field of view of the extended reality display device based on the lens field of view of the image acquisition device, the size ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the size ratio of the test screen area contained in the image to the image. The lens field of view of the image acquisition device and the size ratio of the lens field of view of the image acquisition device to the acquisition field of view are obtained through pre-calibration.

[0020] A third aspect of the present invention provides a field-of-view measurement system for an extended reality display device, including the field-of-view measurement device and the image acquisition device provided in the second aspect of the present invention.

[0021] A fourth aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the field of view measurement method provided in the first aspect of the present invention.

[0022] The fifth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the field of view measurement method provided in the first aspect of the present invention.

[0023] The beneficial effects of this invention are as follows:

[0024] The technical solution described in this invention first uses an image acquisition device to visually capture the test screen displayed by the extended reality display device. Then, through simple image processing, it obtains the ratio of the test screen area contained in the acquired image to the size of the image itself. Finally, based on the lens field of view of the image acquisition device, the ratio of the lens field of view to the acquisition field of view, and the ratio of the test screen area contained in the image to the size of the acquired image, it performs simple calculations to quickly and accurately obtain the field of view of the extended reality display device. This enables rapid testing of extended reality display devices and is suitable for mass production. Attached Figure Description

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0026] Figure 1 A schematic diagram of the observation optics of the extended reality display device of the present invention is shown.

[0027] Figure 2 A flowchart illustrating the field-of-view measurement method for the extended reality display device provided in Embodiment 1 is shown.

[0028] Figure 3 A schematic diagram showing the lens field of view and acquisition field of view of the image acquisition device in Embodiment 1 is shown.

[0029] Figure 4This is a schematic diagram showing an image containing a test screen in Embodiment 1.

[0030] Figure 5 This diagram illustrates the visual relationship between points O, A, B, and C in Example 1 and the human eye's observation point.

[0031] Figure 6 This diagram illustrates the structure of a computer system for measuring the field of view of an extended reality display device provided in Embodiment 2 of the present invention. Detailed Implementation

[0032] To more clearly illustrate the present invention, the following description, in conjunction with embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0033] In extended reality (AR), the field of view is defined as the angle between the edge of the displayed image and the line connecting the user's eyes. The size of the field of view directly determines the user's sense of immersion; therefore, the field of view of all AR display devices must be consistent to ensure a good user experience. For example, a schematic diagram of the observation optics of an AR device that uses an optical engine combined with waveguides to form a virtual image is shown below. Figure 1 As shown, the human eye represents the user's field of view. The human eye can see the virtual image displayed within the field of view of the extended reality display device through the lens. F is the virtual image distance of the AR device.

[0034] The inventors discovered that measuring the field of view of extended reality display devices is currently quite difficult, and the few existing measurement methods generally suffer from problems such as high complexity and low efficiency.

[0035] In view of this, embodiments of the present invention provide a method for measuring the field of view of an extended reality display device, applied to a computer device, the method comprising:

[0036] Control the extended reality display device to display the test screen;

[0037] Control the image acquisition device to acquire images containing the test scene at a preset position; and

[0038] The field of view of the extended reality display device is calculated based on the lens field of view of the image acquisition device, the size ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the size ratio of the test screen area contained in the image to the image. The lens field of view of the image acquisition device and the size ratio of the lens field of view of the image acquisition device to the acquisition field of view are obtained through pre-calibration.

[0039] The extended reality display device field of view measurement method provided in this embodiment first uses an image acquisition device to visually capture the test screen displayed by the extended reality display device. After simple image processing, the size ratio of the test screen area contained in the acquired image to the size of the image is obtained. Then, based on the lens field of view of the image acquisition device, the size ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the size ratio of the test screen area contained in the image to the size of the acquired image, a simple calculation is performed to quickly and accurately obtain the field of view of the extended reality display device. This method can realize rapid testing of various types of extended reality display devices such as virtual reality, augmented reality, and mixed reality, and is suitable for mass production of extended reality display devices.

[0040] Next, the field of view measurement method of the extended reality display device provided in this embodiment will be described through Example 1.

[0041] Example 1

[0042] like Figure 2 As shown, Embodiment 1 provides a method for measuring the field of view of an extended reality display device, including the following steps:

[0043] S210, calibrate the lens field of view of the image acquisition device and the size ratio of the lens field of view to the acquisition field of view of the image acquisition device.

[0044] In a specific example, the calibration method involves using a calibrated target instead of the sensor in the image acquisition device to receive images. The target is placed in the same position as the sensor, and a point light source is moved in front of the lens. Within the lens's field of view, the target can receive a complete image from the light source, resulting in a specific imaging range. This imaging range is larger than the acquisition field of view of the sensor. Then, the imaging field of view of the vision system (lens), i.e., the lens field of view, can be obtained based on the ratio of the distance from the target to the lens to the target's imaging distance. Similarly, the imaging field of view of the sensor, i.e., the acquisition field of view, can be drawn at a 1:1 scale. Thus, the size ratio of the lens field of view to the acquisition field of view of the image acquisition device is calibrated. The distance between the target and the calibration screen of the point light source imaging is set to be the same as the distance between the photosensitive element of the image acquisition device and the visual imaging screen of the extended reality display device when the image is subsequently acquired. That is, the calibration screen of the point light source imaging and the visual imaging screen of the test screen displayed by the extended reality display device are the same actual imaging physical plane.

[0045] For example, Figure 3 The calibrated lens field of view and acquisition field of view of the image acquisition device are shown, wherein the size ratio of the lens field of view to the acquisition field of view of the image acquisition device is [missing information].

[0046] m = OB / OA` Formula (1)

[0047] Where OB is the radius of the field of view of the lens of the image acquisition device; OA` is the distance from the center of the acquisition field of view of the image acquisition device to the first position point (e.g., the center of the long side) at the edge.

[0048] S220: Control the extended reality display device to display the test screen.

[0049] S230: Control the image acquisition device to acquire an image containing the test screen at a preset position.

[0050] In one possible implementation, the extended reality display device displays a solid-color test image, and the image acquisition device acquires an image containing the test image at a preset position. The acquisition background is a solid-color background different from the solid-color test image. For example, the test image is pure white, and the acquisition background is black. Thus, in, for example... Figure 4 In the image shown, the circular test area in the center can be clearly distinguished from the surrounding area, which facilitates the subsequent acquisition of the size ratio of the test area and the overall image.

[0051] In one possible implementation, the preset position is the center position at a preset distance from the display screen of the extended reality display device. The preset distance is, for example, the distance between the user's eye and the display screen when wearing the extended reality display device. The center position indicates that the center of the lens, or the center of the photosensitive element, and the center of the display screen are on the same straight line perpendicular to the direction of the display screen. For example... Figure 1 As shown, the point of view observed by the human eye is the selected acquisition position of the image acquisition device, or the measurement position of the field of view of the extended reality display device. It is understandable that whether VR or MR devices use a display screen, or AR devices use an optical engine combined with an optical waveguide to form a virtual image, the virtual image formed by the extended reality display device through the lens is ultimately imaged onto the imaging target surface at the photosensitive element in the image acquisition device (camera system). The requirement for acquisition is that the test image is contained within the image, i.e., as shown... Figure 4 As shown, the image acquired by the image acquisition device at the preset position must be larger than the test screen displayed on the extended reality display device. This is the requirement for the selection of the optical system in this embodiment.

[0052] The preset position is the center position at a preset distance from the display screen of the extended reality display device, which can achieve the following: Figure 4 The center of the test screen shown coincides with the center of the acquired image, which facilitates the subsequent acquisition of the test screen and image size ratio.

[0053] In one possible implementation, step S230 includes: controlling the image acquisition device to acquire an image containing the test image at a preset position with an imaging surface parallel to the display screen of the extended reality display device. This ensures the accuracy of the final calculated field of view of the extended reality display device.

[0054] S240. The field of view of the extended reality display device is calculated based on the lens field of view of the image acquisition device, the size ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the size ratio of the test screen area contained in the image to the image.

[0055] In one possible implementation, step S240 includes calculating the field of view of the extended reality display device according to the following formula:

[0056] tan θ=(OC / OA)*(tan M) / m

[0057] Wherein, θ is the field of view of the extended reality display device; M is the lens field of view of the image acquisition device; m is the size ratio of the lens field of view of the image acquisition device to the acquisition field of view and the size ratio of the image to the test screen area contained in the image; (OC / OA) is the size ratio of the test screen area contained in the image to the image.

[0058] Furthermore, the size ratio of the lens field of view to the acquisition field of view of the image acquisition device is m = OB / OA', where OB is the radius of the lens field of view of the image acquisition device, OA' is the distance from the center to the first position point at the edge of the acquisition field of view of the image acquisition device; OC is the radius of the test screen area contained in the image, and OA is the distance from the center to the second position point at the edge of the image, wherein the spatial positional relationship between the first position point and the second position point corresponds, that is, for example, as shown in the figure. Figure 3 and Figure 4 As shown, the first position point is the center point of the long side of the acquisition field of view and the second position point is the center point of the long side of the image. Alternatively, the first position point and the second position point can both be the center point of the short side, a vertex in the same direction, or any other arbitrary position point.

[0059] Below, in conjunction with Figure 1-4 The following provides a further explanation of step S240.

[0060] Based on the principles of optical imaging, and in conjunction with the above examples, due to Figure 1 and Figure 4 The photosensitive element plane of the image acquisition device is consistent, so it is combined with Figure 1 and Figure 4 The visual relationship between points O, A, B, C and the human eye observation point M, which is a distance L from point O, can be obtained as shown in the diagram. Figure 5 As shown.

[0061] according to Figure 3 The trigonometric relationship between the lens field of view and the acquisition field of view shown can be derived as follows:

[0062] OB / OA`=(tan M) / (tan N) Formula (2)

[0063] Where M is the lens field of view of the image acquisition device; N is the acquisition field of view of the image acquisition device, that is, the field of view angle occupied by the camera's photosensitive element in the imaging target surface; OB is the radius of the lens field of view of the image acquisition device; and OA' is the distance from the center of the acquisition field of view of the image acquisition device to the first position point (center point of the long side) at the edge.

[0064] Further transformation yields:

[0065] tan N=OA`*(tan M) / OB formula (3)

[0066] according to Figure 4 From the image showing the test screen, the triangular relationship can be derived as follows:

[0067] OA / OC=(tan N) / (tan θ) Formula (4)

[0068] Where OA is the distance between the image center and the second position point (center point of the long side) at the edge. Since the field of view and the image being acquired correspond, OA = OA'. OC is the radius of the test screen area contained in the image, and θ is the field of view angle of the extended reality display device.

[0069] Substituting formula (4) into formula (3) yields:

[0070] tan θ=OC*(tan M) / OB Formula (5)

[0071] Based on formula (1) and OA = OA', we can obtain:

[0072] tan θ=(OC / OA)*(tan M) / m Formula (6)

[0073] in,

[0074] Since the field of view M and size ratio m of the image acquisition device can be obtained during calibration, the field of view θ of the extended reality display device can be obtained simply by calculating the ratio of OC / OA. Specifically, for the acquired image, the distance from the image center to the circular edge of the test screen is the radius OC of the test screen area contained in the image, and the distance from the image center to the second position point (center of the long side) of the edge is OA. Calculating the two Euclidean distances in the image yields the pixel ratio of OC / OA, which is the size ratio of the test screen area contained in the image to the image itself. Substituting this ratio into formula (6) allows for the calculation of the field of view θ of the extended reality display device.

[0075] Example 2

[0076] Example 2 provides a field-of-view measurement device for an extended reality display device, comprising:

[0077] The first control module is used to control the extended reality display device to display the test screen;

[0078] The second control module is used to control the image acquisition device to acquire images containing the test screen at a preset position; and

[0079] The calculation module is used to calculate the field of view of the extended reality display device based on the lens field of view of the image acquisition device, the size ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the size ratio of the test screen area contained in the image to the image. The lens field of view of the image acquisition device and the size ratio of the lens field of view of the image acquisition device to the acquisition field of view are obtained through pre-calibration.

[0080] It should be noted that the principle and working process of the field of view measurement device for the extended reality display device provided in this embodiment are similar to the field of view measurement method provided in Embodiment 1. The relevant parts can be referred to the above description, and will not be repeated here.

[0081] like Figure 6 As shown, a computer system suitable for implementing the field-of-view measurement device of the extended reality display device provided in Embodiment 2 includes a central processing module (CPU), which 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). Various programs and data required for the operation of the computer system are also stored in the RAM. The CPU, ROM, and RAM are connected to each other via a bus. An input / output (I / O) interface is also connected to the bus.

[0082] The following components are connected to the I / O interface: input sections including keyboards, mice, etc.; output sections including liquid crystal displays (LCDs) and speakers, etc.; storage sections including hard disks, etc.; and communication sections including network interface cards such as LAN cards and modems, etc. The communication sections perform communication processing via networks such as the Internet. Drives are also connected to the I / O interface as needed. Removable media, such as disks, optical disks, magneto-optical disks, semiconductor memories, etc., are installed on the drives as needed so that computer programs read from them can be installed into the storage sections as required.

[0083] Specifically, according to this embodiment, the process described in the flowchart above can be implemented as a computer software program. For example, this embodiment includes a computer program product comprising a computer program tangibly embodied on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network via a communication component, and / or installed from a removable medium.

[0084] The flowcharts and schematic diagrams in the accompanying drawings illustrate the architecture, functionality, and operation 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, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the schematic diagram and / or flowchart, and combinations of blocks in the schematic diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0085] The modules described in this embodiment can be implemented in software or hardware. These modules can also be housed within a processor; for example, a processor may be described as including a first control module, a second control module, and a computing module. The names of these modules do not necessarily limit the functionality of the module itself. For example, the computing module may also be described as a "data processing module."

[0086] On the other hand, this embodiment also provides a non-volatile computer storage medium. This non-volatile computer storage medium can be the non-volatile computer storage medium included in the device described in the above embodiments, or it can be a separate non-volatile computer storage medium not assembled into the terminal. The non-volatile computer storage medium stores one or more programs. When the one or more programs are executed by a device, the device causes the device to:

[0087] Control the extended reality display device to display the test screen;

[0088] Control the image acquisition device to acquire images containing the test scene at a preset position; and

[0089] The field of view of the extended reality display device is calculated based on the lens field of view of the image acquisition device, the size ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the size ratio of the test screen area contained in the image to the image. The lens field of view of the image acquisition device and the size ratio of the lens field of view of the image acquisition device to the acquisition field of view are obtained through pre-calibration.

[0090] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0091] It should also be noted that in the description of this invention, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0092] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for measuring the field of view of an extended reality display device, characterized in that, include: Control the extended reality display device to display the test screen; Control the image acquisition device to acquire images containing the test screen at a preset position; as well as The field of view of the extended reality display device is calculated based on the lens field of view of the image acquisition device, the size ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the size ratio of the test screen area contained in the image to the image. The lens field of view of the image acquisition device and the size ratio of the lens field of view of the image acquisition device to the acquisition field of view are obtained through pre-calibration. The calculation of the field of view of the extended reality display device based on the lens field of view of the image acquisition device, the size ratio of the lens field of view to the acquisition field of view, and the size ratio of the test screen area contained in the image to the image size includes calculating the field of view of the extended reality display device according to the following formula: in, The field of view of the extended reality display device; The field of view of the image acquisition device lens; The ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the ratio of the image to the test screen area contained in the image; The ratio of the test area contained in the image to the size of the image; The preset position is the center position at a preset distance from the display screen of the extended reality display device.

2. The method according to claim 1, characterized in that, The size ratio of the lens field of view to the acquisition field of view of the image acquisition device ,in, Let be the radius of the lens field of view of the image acquisition device. The distance from the center of the field of view of the image acquisition device to a first position point at the edge; The radius of the test area contained in the image. The distance between the image center and the second position point on the edge is given, wherein the spatial position relationship between the first position point and the second position point corresponds.

3. The method according to claim 1, characterized in that, The test screen is a solid color screen, and the background of the image captured by the control image acquisition device at the preset position, which includes the test screen, is a solid color background that is different from the solid color screen.

4. The method according to claim 1, characterized in that, The control of the image acquisition device to acquire an image containing the test screen at a preset position includes: controlling the image acquisition device to acquire an image containing the test screen at a preset position with an acquisition angle parallel to the display screen of the extended reality display device.

5. A field-of-view measurement device for an extended reality display device using the method of any one of claims 1-4, characterized in that, include: The first control module is used to control the extended reality display device to display the test screen; The second control module is used to control the image acquisition device to acquire images containing the test screen at a preset position; as well as The calculation module is used to calculate the field of view of the extended reality display device based on the lens field of view of the image acquisition device, the size ratio of the lens field of view of the image acquisition device to the acquisition field of view, and the size ratio of the test screen area contained in the image to the image. The lens field of view of the image acquisition device and the size ratio of the lens field of view of the image acquisition device to the acquisition field of view are obtained through pre-calibration.

6. A field-of-view measurement system for an extended reality display device, characterized in that, Includes the apparatus and image acquisition device as described in claim 5.

7. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the method as described in any one of claims 1-4.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-4.

Images