WO2022012454A1

WO2022012454A1 - Method and apparatus for implementing target object positioning, and display device

Info

Publication number: WO2022012454A1
Application number: PCT/CN2021/105671
Authority: WO
Inventors: 刁鸿浩; 黄玲溪
Original assignee: 北京芯海视界三维科技有限公司; 视觉技术创投私人有限公司
Priority date: 2020-07-15
Filing date: 2021-07-12
Publication date: 2022-01-20
Also published as: CN113947632A

Abstract

The present application relates to the technical field of optics. Disclosed is a method for implementing target object positioning, comprising: obtaining a target object image of a target object; acquiring a target object position of the target object on the basis of the target object image; providing the target object position, and removing the target object image. The method for implementing target object positioning can avoid as much as possible the problem of a large amount of occupied storage space. Also disclosed are an apparatus for implementing target object positioning, a display device, a computer readable storage medium, and a computer program product.

Description

Method, device and display device for realizing target object positioning

This application claims the priority of the Chinese patent application filed on July 15, 2020, with the application number of 202010682318.8 and the invention titled "Method, Apparatus and Display Device for Realizing Target Object Positioning", the entire contents of which are by reference Incorporated in this application.

technical field

The present application relates to the field of optical technology, for example, to a method, an apparatus and a display device for realizing target object positioning.

Background technique

At present, in order to locate the target object, it is usually necessary to obtain the target object image of the target object and perform processing such as storage and analysis.

In the process of implementing the embodiments of the present disclosure, it is found that at least the following problems exist in the related art:

The storage of target object images results in a large amount of storage space.

SUMMARY OF THE INVENTION

In order to provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended to be an extensive review, nor to identify key/critical elements or delineate the scope of protection of these embodiments, but rather serves as a prelude to the detailed description that follows.

Embodiments of the present disclosure provide a method, apparatus, display device, computer-readable storage medium, and computer program product for realizing target object positioning, so as to solve the technical problem that the storage of target object images causes a large amount of storage space to be occupied.

The method for realizing target object positioning provided by the embodiment of the present disclosure includes:

Obtain the target object image of the target object;

Obtain the target object position of the target object based on the target object image;

Provide the target object position and remove the target object image.

In some embodiments, obtaining the target object image of the target object may include:

Obtain the image of the target object through the displacement sensor;

The target object may include the user's eye, and the target object image may include eye space information of the eye.

In some embodiments, the eye space information may include eye plane position information;

Obtain the target object position of the target object, which can include:

The eye depth information is obtained according to the eye plane position information contained in the target object image, thereby obtaining the spatial coordinates of the eye.

In some embodiments, providing the target object location may include:

For the demand side of the position of the target object, the position of the target object is sent actively or passively.

In some embodiments, actively sending the target object position may include: sending the target object position in real time or periodically; or passively sending the target object position may include: sending the target object position based on a received request.

In some embodiments, sending the location of the target object may include:

Send the target object location directly or indirectly to the demand side.

In some embodiments, removing the target object image may include:

The target object image in the displacement sensor is transferred to an entity other than the displacement sensor, so that the target object image does not exist in the displacement sensor; or, the target object image in the displacement sensor is deleted.

In some embodiments, transferring the target object image to the entity may include:

Transfer the target object image to an entity capable of deleting the target object image.

In some embodiments, removing the target object image may include:

Remove the target object image immediately after obtaining the target object position of the target object based on the target object image; or

Remove the target object image immediately after providing the target object location; or

After obtaining the target object position of the target object based on the target object image, or after providing the target object position, the target object image is removed when the removal condition is satisfied.

In some embodiments, the target object image may include a 2D image or a 3D image.

The apparatus for realizing target object positioning provided by the embodiment of the present disclosure includes a processor and a memory storing program instructions, and the processor is configured to execute the above-mentioned method for realizing target object positioning when executing the program instructions.

The display device provided by the embodiment of the present disclosure includes: a displacement sensor and the above-mentioned device for realizing target object positioning;

Wherein, the displacement sensor is configured to perform the following operations under the control of the processor:

Obtain the target object image of the target object;

Provide the target object position and remove the target object image.

In some embodiments, the display device may further include a display controller configured to receive the target object position, from which the pixels of the display device are 3D rendered.

In some embodiments, the number of displacement sensors may be one or more.

In some embodiments, the displacement sensor may be a camera.

The computer-readable storage medium provided by the embodiments of the present disclosure stores computer-executable instructions and is configured to execute the above-mentioned method for realizing target object positioning.

The computer program product provided by the embodiments of the present disclosure includes a computer program stored on a computer-readable storage medium, the computer program includes program instructions, and when the program instructions are executed by a computer, the computer executes the above-mentioned method for realizing target object positioning .

The method, device, display device, computer-readable storage medium, and computer program product for realizing target object positioning provided by the embodiments of the present disclosure can achieve the following technical effects:

Try to avoid a lot of storage space.

The foregoing general description and the following description are exemplary and explanatory only and are not intended to limit the application.

Description of drawings

At least one embodiment is exemplified by the accompanying drawings, which are not intended to limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. does not constitute a proportional limit, and where:

FIG. 1 is a schematic flowchart of realizing target object positioning provided by an embodiment of the present disclosure;

2A, 2B, and 2C are schematic flowcharts of removing a target object image provided by an embodiment of the present disclosure;

3 is a schematic diagram of a device for realizing target object positioning provided by an embodiment of the present disclosure;

4 is a schematic structural diagram of a display device provided by an embodiment of the present disclosure;

FIG. 5 is another schematic structural diagram of a display device provided by an embodiment of the present disclosure;

FIG. 6 is another schematic structural diagram of a display device provided by an embodiment of the present disclosure.

Reference number:

100: Device for realizing target object positioning; 110: Processor; 120: Memory; 130: Communication interface; 140: Bus; 200: Display device; 210: Displacement sensor; 220: Display controller.

detailed description

In order to understand the features and technical contents of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings, which are for reference only and are not intended to limit the embodiments of the present disclosure. In the following technical description, for the convenience of explanation, numerous details are provided to provide a thorough understanding of the disclosed embodiments. However, at least one embodiment may be practiced without these details. In other instances, well-known structures and devices may be shown simplified in order to simplify the drawings.

Referring to FIG. 1 , an embodiment of the present disclosure provides a method for realizing target object positioning, including:

S100: obtain a target object image of the target object;

S200: obtaining the target object position of the target object based on the target object image;

S300: Provide the target object position, and remove the target object image.

In this way, after the position of the target object is obtained based on the target object image of the target object, the target object position can be provided, and the target object image is not retained, but the target object image is removed, so it is possible to avoid occupying a large amount of storage space to store the target object. image. In addition, since the target object image is removed, even if the target object image contains privacy-related content, the content will also be removed, so that privacy issues that may be involved in the content of the target object image can be avoided as much as possible.

Obtain the image of the target object through the displacement sensor;

In some embodiments, the target object image can also be obtained by means other than the displacement sensor.

Obtain the target object position of the target object, which can include:

In some embodiments, the eye plane position information obtained by the displacement sensor includes eye depth information, and then the eye depth information can be obtained according to the eye plane position information, and the eye depth information can be converted into the space of the user's eyes coordinate.

In some embodiments, providing the target object location may include:

In some embodiments, the demand side of the target object location may be a server, an application processor, a router, a user terminal, and the like.

In some embodiments, actively sending the position of the target object may include: sending the position of the target object in real time or periodically.

In some embodiments, when the position of the target object is sent in real time, the position of the target object may be sent in real time after the position of the target object is acquired.

In some embodiments, when the position of the target object is sent periodically, the sending period for sending the position of the target object may be considered according to actual conditions such as the application scenario, the usage time of the displacement sensor, and the workload. Optionally, the sending period can be preset; for example: the sending period is set to a specific duration such as 1 second, 1 minute, and 1 hour, or a specific duration range of greater than or equal to 1 second and less than or equal to 1 hour.

In some embodiments, the target object position may also be sent if the sending condition of the target object position is satisfied.

In some embodiments, when the target object position is sent under the condition that the target object position sending condition is satisfied, the target object position sending condition may be considered according to the actual situation such as the application scenario, the usage time of the displacement sensor, and the workload. Optionally, the sending condition can be set as: the target object position is sent when the number of acquired target object positions reaches a specific value such as 10, 50, 80, or is greater than or equal to 10 and less than or equal to a specific value range such as 80; or, it can be set The sending conditions are: the position of the target object is sent before the displacement sensor is shut down; for example: the position of the target object is sent when the displacement sensor receives the shutdown signal, or after the displacement sensor receives the shutdown signal and before the shutdown is completed.

In some embodiments, passively sending the target object location may include sending the target object location based on the received request.

In some embodiments, where the target object position is sent passively, the target object position may be sent when the request for the target object position is received, or at a specific time after the request for the target object position is received. Optionally, the request for the position of the target object may be a read request for reading the position of the target object; or, it may also be other requests that involve or need to use the position of the target object, for example: request A is not used for direct reading The position of the target object is taken, but it is used to trigger the positioning operation of the target object; then, the displacement sensor can send the position of the target object after receiving the request A. Optionally, the above request may exist in a form that can be recognized by computer instructions or the like.

In some embodiments, sending the location of the target object may include:

Send the target object location directly or indirectly to the demand side.

In some embodiments, in the case of directly sending the position of the target object to the demand side, the displacement sensor can be directly connected to the demand side (eg, wired connection or wireless connection), so as to directly send the target object position to the demand side.

In some embodiments, in the case of indirectly sending the position of the target object to the demand side, the displacement sensor may be indirectly connected to the demand side, for example, the displacement sensor and the demand side may be connected (for example, wired or wireless) with an intermediate connection Nodes (for example: servers, application processors, routers, etc.), the displacement sensor can indirectly send the position of the target object to the demand side through the intermediate node.

In some embodiments, removing the target object image may include:

Transfer the target object image in the displacement sensor to an entity other than the displacement sensor, so that the target object image does not exist in the displacement sensor;

or

Delete the target object image in the displacement sensor.

In some embodiments, when transferring the target object image in the displacement sensor to an entity other than the displacement sensor, the original data of the target object image in the displacement sensor can be transferred to an entity other than the displacement sensor, so that the displacement sensor does not exist target object image. Optionally, the copy of the target object image in the displacement sensor can also be transferred to an entity other than the displacement sensor, and the original data of the target object image in the displacement sensor can be deleted, so that there is no target object image in the displacement sensor. Optionally, whether it is the original data or the copy of the target object image, when the target object image is transferred to an entity other than the displacement sensor, the target object image can be transmitted to the entity other than the displacement sensor in a wired or wireless manner. Optionally, the entity other than the above-mentioned displacement sensor may be an entity that needs to perform subsequent processing such as buffering the image of the target object, for example, a buffer, an image processor, and the like. Optionally, after an entity other than the aforementioned displacement sensor performs subsequent processing such as caching the target object image, the target object image may also be deleted.

In some embodiments, the entity other than the above-mentioned displacement sensor may be an entity capable of deleting the image of the target object, for example, an image processor, a file processor, etc., which are specially used for deleting the image of the target object. Optionally, an entity other than the aforementioned displacement sensor may cache the target object image before deleting the target object image.

In some embodiments, the aforementioned entity may be a hardware entity, such as a physical device capable of processing the image of the target object. Optionally, the above entity may also be a software entity, such as logic software capable of processing the image of the target object.

Referring to FIG. 2A, FIG. 2B, and FIG. 2C, in some embodiments, removing the target object image may include:

In some embodiments, referring to Figure 2A, removing the target object image may include:

S310: Obtain the target object position of the target object based on the target object image;

S311: Immediately remove the target object image.

As can be seen from Figure 2A, the target object image can be removed immediately after the target object position is obtained.

In some embodiments, referring to Figure 2B, removing the target object image may include:

S320: Provide the position of the target object;

S321: Immediately remove the target object image.

As can be seen from Figure 2B, the target object image can be removed immediately after the target object position is provided.

In some embodiments, referring to FIG. 2C, removing the target object image may include:

S330: Obtain the target object position of the target object based on the target object image, or provide the target object position;

S331: Remove the target object image when the removal condition is satisfied.

As can be seen from FIG. 2C , after the target object position is obtained, or after the target object position is provided, the target object image can be removed when the removal condition is satisfied.

In some embodiments, removal conditions may be considered according to actual situations such as application scenarios, usage time of the displacement sensor, workload, and the like. Optionally, the removal condition can be set to: remove the target object image when the workload of the displacement sensor reaches a specific value such as 20%, 50%, 80%, or greater than or equal to 20% and less than or equal to a specific value range such as 80%. .

Referring to FIG. 3 , an embodiment of the present disclosure provides an apparatus 100 for realizing target object positioning, including a processor 110 and a memory 120 storing program instructions. The processor 110 is configured to execute the above-mentioned realization target when executing the program instructions. method of object localization.

In some embodiments, the apparatus 100 for realizing target object positioning shown in FIG. 3 may include:

A processor (processor) 110 and a memory (memory) 120 may also include a communication interface (Communication Interface) 130 and a bus 140 . The processor 110 , the communication interface 130 , and the memory 120 can communicate with each other through the bus 140 . The communication interface 130 may be used for information transfer. The processor 110 may invoke the logic instructions in the memory 120 to execute the method for positioning the target object in the above embodiments.

In addition, the above-mentioned logic instructions in the memory 120 may be implemented in the form of software functional units and may be stored in a computer-readable storage medium when sold or used as an independent product.

As a computer-readable storage medium, the memory 120 may be used to store software programs and computer-executable programs, such as program instructions/modules corresponding to the methods in the embodiments of the present disclosure. The processor 110 executes functional applications and data processing by executing the program instructions/modules stored in the memory 120 , that is, to implement the method for realizing target object positioning in the above method embodiments.

The memory 120 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to use of the terminal device, and the like. In addition, the memory 120 may include high-speed random access memory, and may also include non-volatile memory.

4 , an embodiment of the present disclosure provides a display device 200, including: a displacement sensor 210 and a device for positioning a target object; wherein the displacement sensor 210 is configured to perform the following operations under the control of a processor:

Obtain the target object image of the target object;

Provide the target object position and remove the target object image.

In some embodiments, for the foregoing operations that the displacement sensor 210 can perform, reference may be made to the foregoing corresponding descriptions, for example, including FIG. 1 to FIG. 3 and the corresponding technical descriptions, which will not be repeated here.

Referring to FIG. 5 , in some embodiments, the display device 200 may further include a display controller 220 configured to receive the target object position, and perform 3D rendering on the pixels of the display device 200 accordingly, for example: assigning 3D image display is performed based on the pixels forming the left-eye image and the pixels for forming the right-eye image.

In some embodiments, the display controller 220 may be a timing controller (T-con).

Referring to FIG. 6 , in some embodiments, the number of displacement sensors 210 may be one or more, for example: one, two, three or more.

In some embodiments, the displacement sensor 210 may be a camera. Optionally, the displacement sensor 210 may also be a device such as a radar that can obtain an image of the target object.

In some embodiments, at least two displacement sensors 210 may be used to acquire an image of the target object including eye space information, where the eye space information includes eye plane position information. Optionally, after the corresponding at least two target object images obtained by the at least two displacement sensors 210 with different shooting angles are synthesized and other processing, the eye plane position information included in the obtained target object images includes eye plane position information. depth information, and then the eye depth information can be obtained according to the eye plane position information contained in the target object image, and the eye depth information can be converted into the spatial coordinates of the user's eyes.

In some embodiments, the display device 200 may further include other components for supporting the normal operation of the display device 200 , such as at least one of a communication interface, a frame, a control circuit and other components.

In some embodiments, the aforementioned eyes may include eyeballs, such as eyeballs in both eyes of the user.

In some embodiments, the displacement sensor 210 can also determine the viewing angle/position of the user by determining the visual axis of the eyeball or the like.

The method, device and display device for realizing target object positioning provided by the embodiments of the present disclosure can avoid the problem of a large amount of storage space being occupied as much as possible. In addition, privacy issues that may be involved in the content of the target object image can also be avoided as much as possible.

An embodiment of the present disclosure provides a computer-readable storage medium storing computer-executable instructions, where the computer-executable instructions are configured to execute the above-mentioned method for realizing target object positioning.

An embodiment of the present disclosure provides a computer program product, including a computer program stored on a computer-readable storage medium, where the computer program includes program instructions, and when the program instructions are executed by a computer, the above-mentioned computer is made to execute the above-mentioned realization target object method of positioning.

The above-mentioned computer-readable storage medium may be a transient computer-readable storage medium, and may also be a non-transitory computer-readable storage medium.

The computer-readable storage medium and the computer program product provided by the embodiments of the present disclosure can avoid the problem of a large amount of storage space being occupied as much as possible. In addition, privacy issues that may be involved in the content of the target object image can also be avoided as much as possible.

The technical solutions of the embodiments of the present disclosure may be embodied in the form of a software product. The computer software product is stored in a storage medium and includes at least one instruction to enable a computer device (which may be a personal computer, a server, or a network device, etc. ) to execute all or part of the steps of the methods of the embodiments of the present disclosure. The aforementioned storage medium can be a non-transitory storage medium, including: U disk, removable hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk, etc. A medium that can store program codes, and can also be a transient storage medium.

The foregoing description and drawings sufficiently illustrate the embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, process, and other changes. The examples are only representative of possible variations. Unless expressly required, individual components and functions are optional and the order of operations may vary. Portions and features of some embodiments may be included in or substituted for those of other embodiments. The scope of the disclosed embodiments includes the full scope of the claims, along with all available equivalents of the claims. When used in this application, although the terms "first," "second," etc. may be used in this application to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without changing the meaning of the description, a first element could be termed a second element, and, similarly, a second element could be termed a first element, so long as all occurrences of "the first element" were consistently renamed and all occurrences of "the first element" were named consistently. The "second element" can be renamed consistently. The first element and the second element are both elements, but may not be the same element. Also, the terms used in this application are used to describe the embodiments only and not to limit the claims. As used in the description of the embodiments and the claims, the singular forms "a" (a), "an" (an) and "the" (the) are intended to include the plural forms as well, unless the context clearly dictates otherwise. . Similarly, the term "and/or" as used in this application is meant to include any and all possible combinations of one or more of the associated listings. Additionally, as used in this application, the term "comprise" and its variations "comprises" and/or including and/or the like refer to stated features, integers, steps, operations, elements, and/or The presence of a component does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groupings of these. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, method, or device that includes the element. Herein, each embodiment may focus on the differences from other embodiments, and the same and similar parts between the various embodiments may refer to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method sections disclosed in the embodiments, reference may be made to the descriptions of the method sections for relevant parts.

Those skilled in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software may depend on the specific application and design constraints of the technical solution. Skilled artisans may use different methods for implementing the described functionality for each particular application, but such implementations should not be considered beyond the scope of the disclosed embodiments. Those skilled in the art can clearly understand that, for the convenience and brevity of description, the working process of the system, device and unit described above may refer to the corresponding process in the foregoing method embodiments, and will not be repeated here.

In the embodiments disclosed herein, the disclosed methods and products (including but not limited to apparatuses, devices, etc.) may be implemented in other ways. For example, the apparatus embodiments described above are only illustrative. For example, the division of units may only be a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or may be Integration into another system, or some features can be ignored, or not implemented. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms. Units described as separate components may or may not be physically separated, and components shown as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. This embodiment may be implemented by selecting some or all of the units according to actual needs. In addition, each functional unit in the embodiment of the present disclosure may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.

In the drawings, the width, length, thickness, etc. of structures such as elements or layers may be exaggerated for clarity and descriptiveness. When an element or layer or the like is referred to as being "disposed on" (or "mounted on," "laying on," "adhering to," "coating on," and the like) another element or layer "over" or "above" When referring to “on”, the element or layer and other structures may be directly “disposed on” “above” or “on” the above-mentioned another element or layer, or there may be intervening elements or layers between the above-mentioned another element or layer, etc. structure, even partially embedded in another element or layer as described above.

The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code that contains at least one executable instruction for implementing the specified logical function . In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, operations or steps corresponding to different blocks may also occur in different sequences than those disclosed in the descriptions, and sometimes there is no specific relationship between different operations or steps. order. For example, two consecutive operations or steps may, in fact, be performed substantially concurrently, or they may sometimes be performed in the reverse order, depending upon the functionality involved. Each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented in special purpose hardware-based systems that perform the specified functions or actions, or special purpose hardware implemented in combination with computer instructions.

Claims

A method for realizing target object positioning, comprising:

Obtain the target object image of the target object;

obtaining the target object position of the target object based on the target object image;

The target object position is provided, and the target object image is removed.
The method according to claim 1, wherein the obtaining the target object image of the target object comprises:

Obtain the target object image through a displacement sensor;

The target object includes the user's eye, and the target object image includes eye space information of the eye.
The method of claim 2, wherein the eye space information includes eye plane position information;

Obtain the target object position of the target object, including:

The eye depth information is obtained according to the eye plane position information contained in the target object image, thereby obtaining the spatial coordinates of the eye.
The method of any one of claims 1 to 3, wherein providing the target object position comprises:

For the demand side of the position of the target object, the position of the target object is sent actively or passively.
The method of claim 4, wherein,

Actively sending the position of the target object, including: sending the position of the target object in real time or periodically;

or,

Passively sending the target object position includes sending the target object position based on the received request.
The method of claim 4, wherein transmitting the target object position comprises:

The target object position is sent directly or indirectly to the demand side.
The method according to any one of claims 1 to 6, wherein removing the target object image comprises:

transferring the target object image in the displacement sensor to an entity other than the displacement sensor, so that the target object image does not exist in the displacement sensor;

or

The target object image in the displacement sensor is deleted.
The method of claim 7, wherein transferring the target object image to the entity comprises:

The target object image is transferred to the entity capable of deleting the target object image.
The method of claim 7, wherein removing the target object image comprises:

After obtaining the target object position of the target object based on the target object image, remove the target object image immediately; or

Remove the target object image immediately after providing the target object location; or

After the target object position of the target object is obtained based on the target object image, or the target object position is provided, the target object image is removed when a removal condition is satisfied.
The method of claim 1, wherein the target object image comprises a 2D image or a 3D image.
An apparatus for realizing target object positioning, comprising a processor and a memory storing program instructions, the processor is configured to execute the method according to any one of claims 1 to 10 when executing the program instructions.
A display device, comprising: a displacement sensor and the device according to claim 11;

Wherein, the displacement sensor is configured to perform the following operations under the control of the processor:

Obtain the target object image of the target object;

obtaining the target object position of the target object based on the target object image;

The target object position is provided, and the target object image is removed.
13. The display device of claim 12, further comprising a display controller configured to receive the target object position from which to 3D render pixels of the display device.
The display device according to claim 12 or 13, wherein the number of the displacement sensors is one or more.
The display device of claim 14, wherein the displacement sensor is a camera.
A computer-readable storage medium storing computer-executable instructions arranged to perform the method of any one of claims 1 to 10.
A computer program product comprising a computer program stored on a computer-readable storage medium, the computer program comprising program instructions that, when executed by a computer, cause the computer to perform any one of claims 1 to 10 the method described.