Method for evaluating a three-dimensional reconstruction system and related device

Abstract

This application provides an evaluation method and related apparatus for a 3D reconstruction system. The 3D reconstruction system includes a tracker and a measuring device; the tracker tracks the measuring device; the method includes: acquiring measurement data obtained by the measuring device measuring the same specified reference object in at least two different postures; determining the coordinate data of each measurement data in the coordinate system of the tracker based on the spatial mapping relationship corresponding to the tracking device; and generating accuracy evaluation information for the 3D reconstruction system based on the coordinate data corresponding to the at least two different postures. This method can improve the convenience of accuracy evaluation of the 3D reconstruction system to a certain extent.

Description

Technical Field

[0001] The embodiments described in this application relate to the field of three-dimensional reconstruction technology, and in particular to an evaluation method and related apparatus for a three-dimensional reconstruction system. Background Technology

[0002] In the field of 3D reconstruction, trackers are typically used to monitor measuring devices, and the results of these measurements on the target object are combined to generate a 3D reconstructed model. Currently, users usually assess the accuracy of a 3D reconstruction system by measuring the true values ​​using a standard.

[0003] It is evident that existing technologies rely on the use of standard instruments to evaluate the accuracy of 3D reconstruction systems, which makes the process cumbersome for operators. Summary of the Invention

[0004] In view of this, multiple embodiments of this application aim to provide an evaluation method and related apparatus for a three-dimensional reconstruction system, which can improve the convenience of evaluating the accuracy of a three-dimensional reconstruction system to a certain extent.

[0005] In a first aspect, one embodiment of this application provides an evaluation method for a three-dimensional reconstruction system, the three-dimensional reconstruction system including a tracker and a measuring device; the tracker is used to track the measuring device; the method includes: acquiring measurement data obtained by the measuring device measuring the same specified reference object in at least two different postures; determining the coordinate data of each measurement data in the coordinate system of the tracker based on the spatial mapping relationship corresponding to the tracking device; and generating accuracy evaluation information of the three-dimensional reconstruction system according to the coordinate data corresponding to the at least two different postures.

[0006] Optionally, the measuring device has tracking markers on its surface, and the measuring device includes a first camera and a second camera; the measuring device has at least two different postures, including: the measuring device rotating around a specified axis by a specified angle, and changing the tracking markers identified by the tracker to achieve different postures for the measuring device; wherein, the specified axis passes through the specified reference object and the midpoint between the lens node of the first camera and the lens node of the second camera, and the distance from the lens node of the first camera to the specified axis is equal to the distance from the lens node of the second camera to the specified axis.

[0007] Optionally, the specified angle is 90°.

[0008] Optionally, acquiring measurement data obtained by the measuring device from measuring the same specified reference object in at least two different postures includes: acquiring measurement data measured by the measuring device in one measurement cycle; wherein, the measurement cycle is the period from when the measuring device starts rotating from the initial posture until it returns to the initial posture; the measurement cycle includes the initial posture and at least one intermediate posture obtained by the measuring device rotating a specified angle relative to the specified axis; the intermediate posture is different from the initial posture.

[0009] Optionally, the method further includes: calculating the deviation distance between the coordinate data of the initial pose of the measuring device at the beginning of the measurement cycle and the coordinate data of the device at the beginning pose at the end of the measurement cycle; generating accuracy evaluation information of the three-dimensional reconstruction system based on the coordinate data corresponding to the at least two different poses, including: generating accuracy evaluation information of the three-dimensional reconstruction system based on the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate poses included in the measurement cycle, provided that the deviation distance is not greater than a specified deviation distance threshold.

[0010] Optionally, the method further includes: if the deviation distance is greater than the specified deviation distance threshold, discarding the coordinate data corresponding to the starting pose and the coordinate data corresponding to the intermediate pose included in the measurement cycle.

[0011] Optionally, if the deviation distance is not greater than a specified deviation distance threshold, the accuracy evaluation information of the 3D reconstruction system is generated based on the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose included in the measurement cycle. This includes: calculating the first coordinate range between the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose in the measurement cycle; wherein the first coordinate range is used as an evaluation of the transformation error from the measurement data in the 3D reconstruction system to the coordinate system of the tracker; the accuracy evaluation information includes the transformation error.

[0012] Optionally, the surface of the measuring device is provided with tracking markers; the at least two different postures of the measuring device include: keeping the measuring device facing the tracking markers of the tracker unchanged, changing the distance between the measuring device and the designated reference object, so that the measuring device is in a different posture; or, keeping the measuring device facing the tracking markers of the tracker unchanged, and rotating around the designated reference object, so that the measuring device is in a different posture.

[0013] Optionally, based on the coordinate data corresponding to the at least two different postures, accuracy evaluation information of the three-dimensional reconstruction system is generated, including: calculating the second coordinate range of the coordinate data corresponding to the at least two different postures; wherein the second coordinate range is used as an evaluation of the equipment error of the measuring device; the accuracy evaluation information includes the equipment error.

[0014] Optionally, the designated reference point is a fixed marker point set on a horizontal plane.

[0015] Secondly, one embodiment of this application provides an evaluation device for a three-dimensional reconstruction system, comprising: an acquisition module for acquiring measurement data obtained by the measuring device measuring the same specified reference object in at least two different postures; a determination module for determining the coordinate data of each measurement data in the coordinate system of the tracker based on the spatial mapping relationship corresponding to the measuring device tracked by the tracker; and a generation module for generating accuracy evaluation information of the three-dimensional reconstruction system based on the coordinate data corresponding to the at least two different postures.

[0016] Thirdly, one embodiment of this application also provides an electronic device, the electronic device including a memory and a processor, the memory storing at least one computer program, the at least one computer program being loaded and executed by the processor to implement the method as described above.

[0017] Fourthly, one embodiment of this application also provides a computer-readable storage medium storing at least one computer program that, when executed by a processor, can implement the method described above.

[0018] Fifthly, one embodiment of this application also provides a computer program product for implementing the method as described above.

[0019] In the various embodiments provided in this application, multiple embodiments acquire measurement data obtained by measuring the same specified reference object with a measuring device in at least two different postures, and determine the coordinate data of each measurement data in the coordinate system of the tracker based on the spatial mapping relationship corresponding to the measuring device tracked by the tracker. Then, based on the coordinate data corresponding to at least two different postures, the accuracy evaluation information of the three-dimensional reconstruction system is generated. This realizes the evaluation of the accuracy of the three-dimensional reconstruction system based on the measurement results of the same specified reference object in different postures, and improves the convenience of the accuracy evaluation of the three-dimensional reconstruction system. Attached Figure Description

[0020] Figure 1 A schematic diagram of a three-dimensional reconstruction system provided in one embodiment of this application.

[0021] Figure 2 A schematic diagram of the operation of a three-dimensional reconstruction system provided in one embodiment of this application.

[0022] Figure 3 A flowchart of an evaluation method for a three-dimensional reconstruction system provided in one embodiment of this application.

[0023] Figure 4 A schematic diagram of an evaluation method for a three-dimensional reconstruction system provided in one embodiment of this application.

[0024] Figure 5 A schematic diagram of an evaluation method for a three-dimensional reconstruction system provided in one embodiment of this application.

[0025] Figure 6 A schematic diagram of an evaluation method for a three-dimensional reconstruction system provided in one embodiment of this application.

[0026] Figure 7 A schematic diagram of a module for evaluating a three-dimensional reconstruction system provided in one embodiment of this application.

[0027] Figure 8 A schematic diagram of an electronic device provided according to one embodiment of this application. Detailed Implementation

[0028] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0029] In the description of the embodiments of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] In the field of 3D reconstruction, trackers are typically used to monitor measuring devices, and the results of these measurements on the target object are combined to generate a 3D reconstructed model. To verify the accuracy of the 3D reconstruction system, some methods require the provision of a standard with known dimensional parameters or spatial relationships. Operators then use measuring devices to measure this standard and compare the results with the corresponding reference data to assess the accuracy of the 3D reconstruction system. This method allows for a certain degree of evaluation of the accuracy of the 3D reconstruction system.

[0031] However, in related technologies, when evaluating the accuracy of a 3D reconstruction system, it is usually necessary to prepare a standard and perform measurement and comparison operations around the standard, which makes the accuracy evaluation process cumbersome and the convenience of on-site use low.

[0032] It is evident that further improvements are needed in the relevant technologies regarding how to more conveniently evaluate the accuracy of 3D reconstruction systems.

[0033] Please see Figure 1 and Figure 2 In various embodiments of this application, the 3D reconstruction system may include a variety of electronic devices. Specifically, the 3D reconstruction system may include a tracker and a measuring device. Both the tracker and the measuring device may integrate computing chips and memory, enabling them to possess certain data processing capabilities. In some embodiments, the electronic devices of the 3D reconstruction system may further include a host computer, which can receive data provided by the tracker and the measuring device and perform data processing. The host computer may be a desktop computer, laptop computer, tablet computer, workstation, or server, etc. In some embodiments, the 3D reconstruction system may not include a tracker, and the measuring device may be a handheld scanner.

[0034] Measurement equipment can include, but is not limited to, optical and non-optical measurement equipment. Optical measurement equipment can include, but is not limited to, visible light scanners, structured light scanners, laser scanners, and light pens. Non-optical measurement equipment can include, but is not limited to, ultrasonic scanners and X-ray scanners. For example, a laser scanner can measure the distance to an object's surface by emitting a laser beam and detecting changes in the laser's reflection time or phase, thus generating high-precision scan data. Specifically, this scan data can be three-dimensional point cloud data. A structured light scanner can project a structured light pattern (such as stripes or a dot matrix) onto an object's surface and generate scan data by detecting the light reflected from the object's surface.

[0035] This application does not specify the particular type and principle of the measuring equipment.

[0036] The measuring device possesses tracking features, which can serve as its positioning characteristics. Multiple tracking features can be present and deployed at various locations on the measuring device, allowing for tracking of the device's spatial pose. In some embodiments, the tracking features may include, but are not limited to, marker points, coded points, stereo targets, geometric features of objects, and other features that can be acquired and identified by the tracker. The marker points can be reflective, in which case the tracker emits light and receives the reflected light. In some embodiments, the marker points can be luminescent, in which case the tracker can directly receive the light emitted by the marker points.

[0037] A tracker can be used based on stereo vision tracking principles to output tracking information corresponding to the position and orientation of a measuring device in space. This tracking information can be used to determine pose information representing the spatial orientation of the measuring device. Each tracker includes a camera. The number of cameras in a tracker can be one or more. Preferably, the tracker is a binocular tracker or a multi-view tracker. The number of cameras in different trackers can be the same or different. The tracker can form tracking information from images captured by the cameras. Specifically, the camera can continuously capture multiple image frames, with small time intervals between the multiple image frames, resulting in corresponding differences between the multiple image frames as the measuring device moves in space. The tracking information can include frame information. Each frame information can include image frames captured by multiple cameras of the corresponding tracker at the same time. It can be understood that each frame information can include at least one image frame.

[0038] The evaluation methods for 3D reconstruction systems can be applied to the aforementioned 3D reconstruction systems. Specifically, these methods can be applied to one or more electronic devices within the 3D reconstruction system. Those skilled in the art can deploy the electronic devices that implement the evaluation methods for the 3D reconstruction system according to the specific circumstances.

[0039] Please see Figure 3 This application provides an evaluation method for a three-dimensional reconstruction system. The three-dimensional reconstruction system includes a tracker and a measuring device; the tracker is used to track the measuring device. This evaluation method for the three-dimensional reconstruction system is applied to an electronic device within the three-dimensional reconstruction system. The evaluation method for the three-dimensional reconstruction system may include the following steps.

[0040] Step S110: Obtain measurement data from the measuring device measuring the same specified reference object in at least two different orientations.

[0041] Step S120: Based on the spatial mapping relationship corresponding to the measuring device tracked by the tracker, determine the coordinate data of each measurement data in the coordinate system of the tracker.

[0042] Step S130: Generate accuracy evaluation information for the three-dimensional reconstruction system based on the coordinate data corresponding to the at least two different postures.

[0043] In this embodiment, the evaluation method of the 3D reconstruction system can be executed by an electronic device. The electronic device can be at least one of a tracker, a measuring device, or a host computer within the 3D reconstruction system. The 3D reconstruction system may include a tracker and a measuring device, whereby the tracker tracks the measuring device to obtain tracking results characterizing the spatial state of the measuring device. Thus, the electronic device can uniformly process the measurement results obtained by the measuring device under different postures based on the tracking results from the tracker, thereby evaluating the accuracy of the 3D reconstruction system.

[0044] In this embodiment, the electronic device can be used to acquire measurement data obtained by the measuring device measuring the same designated reference object in at least two different postures. The designated reference object can be understood as a reference object repeatedly measured in different postures and used as a basis for accuracy evaluation. It should be noted that the true value of the designated reference object does not need to be predetermined. It can be understood that the designated reference object in this application is mainly used as a unified reference object for repeated measurements in different postures. The electronic device can evaluate the accuracy of the 3D reconstruction system by comparing the consistency of the measurement results corresponding to the same designated reference object in different postures, without relying on comparing the measurement results with the preset true value of the designated reference object. Thus, the designated reference object does not need to be a standard with known size parameters or known spatial positional relationships, as long as it can be stably and repeatedly measured by the measuring device in different postures. Specifically, the designated reference object can be a single reference point, multiple reference points, feature markers, a sphere, a corner structure, or other objects that can be stably measured by the measuring device. The measurement data can be understood as the data output by the measuring device for the designated reference object in the corresponding posture, used to characterize the measurement results of the designated reference object on the measuring device side. Specifically, the measurement data may include spatial point data, point cloud data, feature point location data, or other information characterizing the spatial position of the specified reference object. In some embodiments, the measuring device can measure the same specified reference object in at least two different postures, where the at least two different postures can be multiple postures with different orientations, distances, or rotation states relative to the specified reference object. In this way, the electronic device can acquire measurement data of the same specified reference object in different postures, serving as the data basis for subsequent unified coordinate comparison.

[0045] In this embodiment, the electronic device can also determine the coordinate data of each measurement data in the tracker's coordinate system based on the spatial mapping relationship corresponding to the tracking and measuring device. The spatial mapping relationship can be understood as a mapping relationship characterizing the positional correspondence between the measurement coordinate system corresponding to the measuring device and the tracker's coordinate system. Specifically, the electronic device can determine the spatial state of the measuring device relative to the tracker in each posture based on the tracking results output by the tracker, and further transform the measurement data obtained in each posture into the tracker's coordinate system based on the spatial state. The coordinate data can be understood as the corresponding coordinate results of the measurement data in the tracker's coordinate system, used to uniformly characterize the position of the specified reference object in the tracker's coordinate system under different postures. Thus, even if the measuring device completes the measurement of the same specified reference object in different postures, the electronic device can still unify the measurement results from different postures into the tracker's coordinate system for comparison.

[0046] In this embodiment, the electronic device can generate accuracy evaluation information for the 3D reconstruction system based on coordinate data corresponding to at least two different postures. Accuracy evaluation information can be understood as an evaluation result characterizing the accuracy of the 3D reconstruction system. Specifically, the electronic device can compare and process coordinate data corresponding to different postures to determine whether there are fluctuations in the measurement results for the same specified reference object under different postures within the tracker's coordinate system, and the error corresponding to these fluctuations. In some embodiments, accuracy evaluation information may include coordinate deviation, coordinate fluctuation range, error characterization results, or other data used to evaluate the accuracy of the 3D reconstruction system. Specifically, the electronic device acquires measurement data obtained by a measuring device measuring the same specified reference object in at least two different postures, maps the measurement data uniformly to the tracker's coordinate system, and then generates accuracy evaluation information based on the coordinate data corresponding to different postures.

[0047] In the various embodiments provided in this application, multiple embodiments acquire measurement data obtained by measuring the same specified reference object with a measuring device in at least two different postures, and determine the coordinate data of each measurement data in the coordinate system of the tracker based on the spatial mapping relationship corresponding to the measuring device tracked by the tracker. Then, based on the coordinate data corresponding to at least two different postures, the accuracy evaluation information of the three-dimensional reconstruction system is generated. This realizes the evaluation of the accuracy of the three-dimensional reconstruction system based on the measurement results of the same specified reference object in different postures, and improves the convenience of the accuracy evaluation of the three-dimensional reconstruction system.

[0048] Please see Figure 4In some embodiments, the measuring device has tracking markers on its surface, and the measuring device includes a first camera and a second camera; the measuring device has at least two different postures, including: the measuring device rotating around a specified axis by a specified angle, changing the tracking markers identified by the tracker to achieve different postures; wherein the specified axis passes through the specified reference object and the midpoint between the lens node of the first camera and the lens node of the second camera, and the distance from the lens node of the first camera to the specified axis is equal to the distance from the lens node of the second camera to the specified axis.

[0049] In this embodiment, when the electronic device acquires measurement data obtained by the measuring device measuring the same specified reference object in at least two different postures, the at least two different postures of the measuring device can be formed by rotating the measuring device around a specified axis by a specified angle. Specifically, the surface of the measuring device may be provided with tracking markers, which can serve as tracking features for the tracker to identify, characterizing the position and posture of the measuring device in space. The measuring device includes a first camera and a second camera, enabling the measuring device to measure the specified reference object based on the first and second cameras. Thus, the electronic device can determine the different postures of the measuring device during the rotation of the measuring device, combined with the tracker's identification results of the tracking markers, and acquire measurement data for the specified reference object in each posture.

[0050] In this embodiment, the measuring device can be operated to rotate around the specified axis by the specified angle. The specified axis can be a reference axis used to define the posture change mode of the measuring device. Accordingly, after the measuring device rotates around the specified axis by the specified angle, the tracking marker points identified by the tracker will change, thereby indicating that the measuring device has been in different postures. Changing the tracking marker points identified by the tracker may include a change in the number of tracking marker points identified by the tracker, a change in the spatial distribution relationship of the various tracking marker points identified by the tracker, or a change in the combination of tracking marker points identified by the tracker. Thus, the electronic device can acquire measurement data corresponding to the same specified reference object in multiple postures by changing the posture of the measuring device itself without changing the specified reference object.

[0051] In this embodiment, the designated axis passes through the designated reference object and the midpoint between the lens nodal point of the first camera and the lens nodal point of the second camera. The lens nodal point can be a node position in the corresponding camera imaging geometry, used to characterize the optical reference position of the camera when measuring externally. The midpoint between the lens nodal points of the first camera and the second camera can be an intermediate reference position between the corresponding imaging positions of the first and second cameras in the measuring device. Thus, having the designated axis pass through both the designated reference object and the intermediate reference positions corresponding to the first and second cameras facilitates the rotation of the measuring device around the designated axis while maintaining its spatial position.

[0052] In this embodiment, the distance from the lens node of the first camera to the designated axis is equal to the distance from the lens node of the second camera to the designated axis. Thus, the first and second cameras can form a relatively symmetrical geometric distribution relative to the designated axis. When the electronic device subsequently determines coordinate data based on measurement data from different postures, it reduces the additional influence introduced by the uneven distribution of the first and second cameras relative to the designated axis, making the measurement results obtained for the same designated reference object under different postures more suitable for evaluating the accuracy of the 3D reconstruction system.

[0053] In this embodiment, when the measuring device is in a first posture, the first camera and the second camera measure the designated reference object to obtain measurement data corresponding to the first posture. Then, the measuring device rotates around the designated axis by the designated angle, causing the tracker to re-identify the tracking marker point after the rotation and determine that the measuring device is in a second posture. The first camera and the second camera then measure the same designated reference object to obtain measurement data corresponding to the second posture. In this way, the electronic device can acquire measurement data obtained by the measuring device from the same designated reference object in at least two different postures, so that the coordinate data of each measurement data point in the tracker's coordinate system can be determined based on the spatial mapping relationship corresponding to the measuring device tracked by the tracker.

[0054] For example, the measuring device can be a binocular scanning device, with the first camera and the second camera respectively positioned on opposite sides of the device. The designated reference point can be a single marker point located in the area to be evaluated. The binocular scanning device can be operably rotated about a designated axis, which passes through the center of the marker point and the midpoint between the lens nodes of the first and second cameras. Since the distances from the first and second cameras to the designated axis are equal, the measurement relationships of the first and second cameras relative to the marker ball have good correspondence before and after the binocular scanning device rotates. Thus, the electronic device can more easily acquire measurement data obtained by the binocular scanning device for the same marker ball under different postures and use it for subsequent accuracy evaluation.

[0055] In some implementations, the specified angle is 90°.

[0056] In this embodiment, the specified angle can be the rotation angle corresponding to the switching of the measuring device from one posture to another around the specified axis. Thus, setting the specified angle to 90° allows the measuring device to form different postures with relatively clear angular intervals during rotation around the specified axis, facilitating the electronic device to distinguish the measurement data corresponding to different postures. Specifically, with the specified angle at 90°, the measuring device forms a new posture relative to the previous posture each time it rotates around the specified axis. In this way, the electronic device can acquire measurement data obtained from the same specified reference object when the measuring device is in different postures such as 0°, 90°, 180°, and 270°, and return to the initial posture after the measuring device continues to rotate. In this way, the measuring device can form multiple postures with consistent angular intervals during one rotation around the specified axis, facilitating the subsequent conversion of measurement data obtained from different postures into the tracker's coordinate system for comparison. Furthermore, the specified angle of 90° also facilitates the step-by-step rotation of the measuring device by the operator.

[0057] In some embodiments, the electronic device can acquire measurement data measured by the measuring device in a measurement cycle; wherein the measurement cycle is the period from when the measuring device starts rotating from an initial pose until it returns to the initial pose; the measurement cycle includes the initial pose and at least one intermediate pose obtained by rotating the measuring device relative to the specified axis by a specified angle; the intermediate pose is different from the initial pose.

[0058] In this embodiment, when the electronic device acquires measurement data obtained by the measuring device from measuring the same specified reference object in at least two different postures, this can be achieved by acquiring the measurement data measured by the measuring device within one measurement cycle. The measurement cycle can be the process of the measuring device rotating from an initial pose until it returns to the posture corresponding to the initial pose. The initial pose can be the posture of the measuring device at the beginning of the measurement cycle, and the intermediate pose can be the posture obtained after the measuring device rotates relative to the specified axis by the specified angle, and the intermediate pose is different from the initial pose. Thus, the electronic device can organize multiple postures of the measuring device during a complete rotation process into the same measurement cycle, so as to acquire the measurement data corresponding to the same specified reference object in different postures within the measurement cycle.

[0059] Specifically, at the beginning of the measurement cycle, the measuring device can be in the initial pose and measure the designated reference object to obtain measurement data corresponding to the initial pose. Then, the measuring device can rotate around the designated axis by the designated angle to a middle pose, and measure the designated reference object again to obtain measurement data corresponding to the middle pose. In some embodiments, the measuring device can rotate around the designated axis by the designated angle multiple times consecutively during the measurement cycle to form multiple middle poses, and measure the designated reference object in each middle pose. Thus, the electronic device can acquire the initial pose and measurement data corresponding to at least one middle pose within the same measurement cycle.

[0060] In this embodiment, the end condition of the measurement cycle can be that the measuring device returns to the initial pose after experiencing one or more intermediate poses. This can be understood as the pose change process of the measuring device during the measurement cycle being a closed-loop pose change process. Thus, the electronic device can not only acquire measurement data corresponding to different poses of the measuring device, but also enable the measuring device to return to the initial pose at the end of the measurement cycle. This ensures good comparability of the measurement data corresponding to each pose in the measurement cycle and provides a data foundation for subsequent comparison processing based on the data corresponding to the initial pose and the intermediate poses.

[0061] Specifically, if the specified angle is 90°, the measuring device can start from the initial pose, sequentially rotate to multiple intermediate poses, and return to the initial pose after further rotation. For example, the initial pose may correspond to a 0° pose, and the intermediate poses may include 90°, 180°, and 270° poses. After the measuring device continues to rotate, it can return to the 0° pose. The electronic device can acquire measurement data of the same specified reference object when the measuring device is in the 0°, 90°, 180°, 270° poses, and when it returns to the 0° pose. In this way, the electronic device can acquire measurement data for a complete measurement cycle, so that the coordinate data of each measurement data in the coordinate system of the tracker can be determined based on the spatial mapping relationship corresponding to the measuring device.

[0062] In some implementations, the electronic device can calculate the deviation distance between the coordinate data of the initial pose at the beginning of the measurement cycle and the coordinate data of the initial pose at the end of the measurement cycle; if the deviation distance is not greater than a specified deviation distance threshold, the accuracy evaluation information of the three-dimensional reconstruction system is generated based on the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose included in the measurement cycle.

[0063] In this embodiment, the electronic device can calculate the deviation distance between the coordinate data of the initial pose at the beginning of the measurement cycle and the coordinate data of the device at the end of the measurement cycle. The deviation distance can be a distance representing the degree of deviation between the corresponding coordinate data when the measuring device is in the initial pose twice within the same measurement cycle. Since the measuring device returns to the initial pose at the end of the measurement cycle, if the difference between the coordinate data of the initial pose at the beginning and the coordinate data of the device at the end is small, it indicates that the measurements in the measurement cycle have good repeatability. Thus, the electronic device can use the deviation distance to determine the validity of the measurement data corresponding to the measurement cycle.

[0064] In this embodiment, after converting the measurement data to the tracker's coordinate system, the electronic device can extract the coordinate data corresponding to the initial pose at the start of the measurement cycle and the coordinate data corresponding to the initial pose at the end of the measurement cycle, and calculate the deviation distance between the two. In some embodiments, the electronic device can determine the deviation distance based on the spatial distance between the two coordinate positions. Thus, the consistency between the coordinate data corresponding to the same initial pose in two consecutive measurements can be used to characterize whether the measurement cycle is affected by external interference, operational offset, or attitude recovery error.

[0065] In this embodiment, the electronic device can generate accuracy evaluation information for the 3D reconstruction system based on the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose included in the measurement cycle, provided that the deviation distance is not greater than a specified deviation distance threshold. The specified deviation distance threshold can be a preset threshold used to determine whether the measurement cycle meets the accuracy evaluation requirements. Thus, when the deviation distance is not greater than the specified deviation distance threshold, it indicates that the measuring device has returned well to the initial pose at the end of the measurement cycle. Correspondingly, the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose acquired in the measurement cycle have good comparability, making them more suitable for generating accuracy evaluation information for the 3D reconstruction system.

[0066] In this embodiment, when the deviation distance is not greater than the specified deviation distance threshold, the electronic device can select the coordinate data corresponding to the initial pose at the beginning of the measurement cycle, and the coordinate data corresponding to each intermediate pose during the measurement cycle, as the data set for generating the accuracy evaluation information. It can be understood that the coordinate data at the beginning pose at the end of the measurement cycle is mainly used to determine the validity of the measurement cycle, while the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate poses at the beginning of the measurement cycle are used to reflect the coordinate changes obtained by the measuring device under different postures for the same specified reference object. Thus, while ensuring the validity of the measurement cycle, the valid coordinate data in the measurement cycle can be used to generate the accuracy evaluation information, thereby reducing the impact of invalid measurement cycles on the accuracy evaluation results.

[0067] For example, the measuring device can start measuring the same marker point from the initial pose corresponding to 0°, and then measure at intermediate poses corresponding to 90°, 180°, and 270° after each subsequent 90° rotation around the specified axis, before continuing to rotate and returning to the initial pose corresponding to 0°. After converting the data from each measurement to the tracker's coordinate system, the electronic device can calculate the deviation distance between the coordinate data at the initial pose corresponding to 0° and the coordinate data at the point of return to the initial pose corresponding to 0°. For example, the specified deviation distance threshold can be 0.1 mm. When the deviation distance is no greater than 0.1 mm, the electronic device can generate accuracy evaluation information for the 3D reconstruction system based on the coordinate data at the initial pose corresponding to 0° and the coordinate data at the intermediate poses corresponding to 90°, 180°, and 270°. This allows the accuracy evaluation information to be established under the condition that the measurement cycle meets the repeatability requirements.

[0068] In some implementations, the electronic device may discard the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose included in the measurement cycle if the deviation distance is greater than the specified deviation distance threshold.

[0069] In this embodiment, after calculating the deviation distance, if the deviation distance is greater than the specified deviation distance threshold, the electronic device can discard the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate poses included in the measurement cycle. This avoids using coordinate data that does not meet repeatability requirements to generate the accuracy evaluation information of the 3D reconstruction system, reducing the impact of abnormal measurement cycles on the accuracy evaluation results. Specifically, a deviation distance greater than the specified deviation distance threshold indicates that the measuring device has not returned well to the initial pose at the end of the measurement cycle, or that there is significant external interference, operational offset, or pose recovery error during the measurement cycle. In this case, the electronic device can remove the coordinate data corresponding to the initial pose at the beginning of the measurement cycle, as well as the coordinate data corresponding to each intermediate pose, from the data set used to generate the accuracy evaluation information. This ensures that the data subsequently used for accuracy evaluation has better validity.

[0070] For example, the measuring device can start measuring the same marker point from the initial pose corresponding to 0°, and then measure at intermediate poses corresponding to 90°, 180°, and 270° after each subsequent 90° rotation around the specified axis, before continuing to rotate and returning to the initial pose corresponding to 0°. After converting the data from each measurement to the tracker's coordinate system, the electronic device can calculate the deviation distance between the coordinate data from the initial pose corresponding to 0° and the coordinate data from the initial pose corresponding to 0°. For example, the specified deviation distance threshold can be 0.1 mm. When the deviation distance is greater than 0.1 mm, the electronic device can discard the coordinate data from the initial pose corresponding to 0°, as well as the coordinate data from the intermediate poses corresponding to 90°, 180°, and 270° in that measurement cycle. This avoids generating the accuracy evaluation information based on abnormal data in that measurement cycle.

[0071] In some implementations, the electronic device can statistically analyze the first coordinate range between the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose during the measurement cycle; wherein, the first coordinate range serves as an evaluation of the transformation error from the measurement data in the 3D reconstruction system to the coordinate system of the tracker; the accuracy evaluation information includes the transformation error.

[0072] In this embodiment, when the deviation distance is not greater than the specified deviation distance threshold, the electronic device can generate accuracy evaluation information for the 3D reconstruction system based on the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose included in the measurement cycle. Specifically, the electronic device can statistically analyze the first coordinate range between the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose in the measurement cycle. The first coordinate range can be a range data used to characterize the dispersion of coordinate data corresponding to multiple poses of the same specified reference object within the measurement cycle. Thus, when the measurement cycle meets the repeatability requirement, the first coordinate range can be used to characterize the fluctuation between coordinate data under different poses. Specifically, since the measurement objects corresponding to the initial pose and the intermediate pose are the same specified reference object, and each measurement data has been converted to the coordinate system of the tracker, if the conversion process from the measurement data to the coordinate system of the tracker is accurate, the coordinate data corresponding to the specified reference object under different poses should be relatively close; conversely, if the conversion process from the measurement data to the coordinate system of the tracker has a large error, the coordinate data corresponding to the specified reference object under different poses will exhibit large fluctuations. Thus, the electronic device can use the first coordinate range as an evaluation of the transformation error from the measurement data in the three-dimensional reconstruction system to the coordinate system of the tracker, and the accuracy evaluation information includes the transformation error.

[0073] For example, the measuring device can start measuring the same marker point from the initial pose corresponding to 0°, and then measure at intermediate poses corresponding to 90°, 180°, and 270° after each 90° rotation around the specified axis. If the deviation distance is no greater than 0.1 mm, the electronic device can calculate the first coordinate range of the coordinate data corresponding to 0°, 90°, 180°, and 270°. If the first coordinate range is small, it indicates that the transformation error from the measurement data to the tracker's coordinate system is small; if the first coordinate range is large, it indicates that the transformation error from the measurement data to the tracker's coordinate system is large. Thus, the electronic device can write the transformation error determined by the first coordinate range into the accuracy evaluation information to evaluate the accuracy of the 3D reconstruction system.

[0074] Please see Figure 5 and Figure 6 In some embodiments, the at least two different orientations of the measuring device include: keeping the measuring device facing the tracking marker of the tracker unchanged, and changing the distance between the measuring device and the designated reference object to put the measuring device in a different orientation; or, keeping the measuring device facing the tracking marker of the tracker unchanged, and rotating around the designated reference object to put the measuring device in a different orientation.

[0075] In this embodiment, keeping the tracking markers of the measuring device facing the tracker unchanged can be achieved by: maintaining the correspondence between the tracking markers continuously identified by the tracker during changes in the attitude of the measuring device, or by using the same set of tracking markers primarily to characterize the spatial state of the measuring device. This reduces the additional impact introduced by significant changes in the object identified by the tracker, making the measurement data acquired under different attitudes more suitable for comparison.

[0076] In some implementations, the electronic device can change the distance between the measuring device and the designated reference object, thus placing the measuring device in different orientations. This distance change can be a relative positional change resulting from the measuring device moving closer to, further away from, rising above, or falling below the designated reference object. In this way, while the measuring device's orientation towards the tracking marker point of the tracker remains constant, the electronic device can acquire measurement data obtained by the measuring device at the same designated reference object under different distance conditions.

[0077] In some embodiments, the electronic device can also rotate around a designated reference object while keeping the measuring device facing the tracking marker point of the tracker unchanged, thereby placing the measuring device in different orientations. Rotation around the designated reference object can be understood as a change in the orientation of the measuring device relative to the designated reference object, while the designated reference object remains unchanged. In this way, the electronic device can acquire measurement data obtained by the measuring device with respect to the same designated reference object from different orientations.

[0078] Specifically, the electronic device can measure the designated reference object when the measuring device is in a first posture, obtaining measurement data corresponding to the first posture. Then, while keeping the measuring device facing the tracking marker point of the tracker unchanged, the electronic device can change the distance between the measuring device and the designated reference object, or rotate the measuring device around the designated reference object, to bring the measuring device into a second posture, and then measure the designated reference object again to obtain measurement data corresponding to the second posture. In this way, the electronic device can acquire measurement data obtained by the measuring device on the same designated reference object in at least two different postures, so that it can subsequently determine the coordinate data of each measurement data in the coordinate system of the tracker based on the spatial mapping relationship corresponding to the measuring device tracked by the tracker.

[0079] For example, the measuring device can be a binocular scanning device, and the designated reference point can be a single marker point. In one approach, the operator can, while keeping the binocular scanning device facing the tracking marker point of the tracker unchanged, first measure the marker point with the binocular scanning device at a lower position, and then raise the binocular scanning device to measure the same marker point again, thereby obtaining measurement data under different distance conditions. In another approach, the operator can also, while keeping the binocular scanning device facing the tracking marker point of the tracker unchanged, rotate the binocular scanning device to the left or right around the marker point, and measure the same marker point in the rotated posture. In this way, the electronic device can acquire the measurement data obtained by the binocular scanning device for the same marker point in different postures and use it for subsequent accuracy evaluation.

[0080] In some embodiments, the electronic device can statistically analyze the second coordinate range of the coordinate data corresponding to the at least two different attitudes; wherein the second coordinate range serves as an evaluation of the device error of the measuring device; the accuracy assessment information includes the device error.

[0081] In this embodiment, the electronic device can statistically analyze the second coordinate range of the coordinate data corresponding to the at least two different postures. The second coordinate range can be a range data used to characterize the dispersion of the coordinate data corresponding to the same specified reference object when the measuring device is in at least two different postures. Thus, the electronic device can characterize the coordinate fluctuation of the measuring device when measuring the same specified reference object in different postures based on the second coordinate range. Specifically, while keeping the measuring device facing the tracking marker point of the tracker unchanged, the tracker maintains a relatively consistent tracking reference for the measuring device. In this case, if the measuring device still experiences significant fluctuations in the corresponding coordinate data after changing the distance to the specified reference object or rotating around the specified reference object, these fluctuations can largely reflect the measurement deviation of the measuring device itself. Based on this, the electronic device can use the second coordinate range as an evaluation of the device error of the measuring device, and the accuracy evaluation information includes the device error. Thus, the measurement stability exhibited by the measuring device in different postures can be transformed into a quantitative evaluation result of the device error.

[0082] In some embodiments, the electronic device can separately calculate the range of the coordinate data corresponding to the at least two different attitudes in each coordinate direction, and use the range in each coordinate direction as the second coordinate range; alternatively, it can perform overall statistics on the spatial coordinate changes corresponding to the at least two different attitudes, and use the statistical result as the second coordinate range. In this application, the specific statistical method for the second coordinate range is not limited, as long as it can be used to evaluate the equipment error of the measuring device.

[0083] Specifically, if the second coordinate range is small, it indicates that the measuring device has good measurement consistency when measuring the same specified reference object under different postures, and the corresponding device error is small; if the second coordinate range is large, it indicates that the measurement results of the measuring device fluctuate greatly under different postures, and the corresponding device error is large. The accuracy evaluation information includes the device error determined by the second coordinate range, which is used to evaluate the accuracy of the three-dimensional reconstruction system.

[0084] In some implementations, the designated reference point is a fixed marker point set on a horizontal plane.

[0085] In this embodiment, the fixed marker point can be a marker point whose spatial position remains unchanged during the evaluation process, serving as a reference object for repeated measurements by the measuring device in different postures. The horizontal plane can be the planar position where the fixed marker point is installed, providing a relatively stable base for its placement. Thus, setting the designated reference object as a fixed marker point on the horizontal plane facilitates the electronic device acquiring measurement data from the same stable reference object when the measuring device is in different postures, thereby facilitating subsequent comparison of the corresponding coordinate data under different postures.

[0086] Specifically, the fixed marker points can be fixedly set on the ground, platform surface, workbench surface, or other stable horizontal surfaces. During the evaluation process, the position of the fixed marker points does not change, and the measuring device can measure the same fixed marker point multiple times. This reduces the impact of changes in the position of the designated reference object on the measurement results, making the measurement data corresponding to at least two different postures more suitable for generating accuracy evaluation information for the 3D reconstruction system.

[0087] Please see Figure 7 This application provides an evaluation device for a three-dimensional reconstruction system. The evaluation device includes: an acquisition module, a determination module, and a generation module.

[0088] The acquisition module is used to acquire measurement data obtained by the measuring device measuring the same specified reference object in at least two different postures.

[0089] The determination module is used to determine the coordinate data of each measurement data in the coordinate system of the tracker based on the spatial mapping relationship corresponding to the measurement device tracked by the tracker.

[0090] The generation module is used to generate accuracy evaluation information for the three-dimensional reconstruction system based on the coordinate data corresponding to the at least two different postures.

[0091] In this embodiment, the specific functions and effects of the evaluation device of the three-dimensional reconstruction system can be explained by referring to other embodiments of this application, and will not be repeated here.

[0092] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, causes the processor to implement the method as described above.

[0093] This application also provides a computer program product containing instructions that, when executed by a processor, implement the method as described above.

[0094] Please see Figure 8 Embodiments of this application may provide an electronic device, the electronic device comprising: a memory, and one or more processors communicatively connected to the memory; the memory storing instructions executable by the one or more processors, the instructions being executed by the one or more processors to cause the one or more processors to implement the method as described above.

[0095] In some embodiments, the electronic device may include a processor, a storage medium, and a communication interface connected to a system bus. The storage medium may store related computer programs.

[0096] It is understood that the specific examples in this document are only intended to help those skilled in the art better understand the embodiments of this application, and are not intended to limit the scope of the invention.

[0097] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0098] It is understood that the various implementation methods described in this application can be implemented individually or in combination, and the implementation methods in this application are not limited in this respect.

[0099] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0100] It is understood that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by the integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0101] It is understood that the memory in the embodiments of this application may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Specifically, non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may be random access memory (RAM). It should be noted that the memory in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0102] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0103] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the aforementioned method implementations, and will not be repeated here.

[0104] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0105] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0106] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0107] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause an electronic device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0108] The above description is merely a specific embodiment of this application, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A method of evaluating a three-dimensional reconstruction system, characterized in that, The 3D reconstruction system includes a tracker and a measuring device; the tracker is used to track the measuring device. The method includes: Acquire measurement data obtained by the measuring device measuring the same specified reference object in at least two different orientations; Based on the spatial mapping relationship corresponding to the tracking device, the coordinate data of each measurement data in the coordinate system of the tracker are determined respectively; Based on the coordinate data corresponding to the at least two different postures, accuracy evaluation information of the three-dimensional reconstruction system is generated.

2. The method of claim 1, wherein, The measuring device has tracking markers on its surface and includes a first camera and a second camera. The measuring device can be in at least two different postures: rotating the measuring device around a specified axis by a specified angle, thereby changing the tracking markers detected by the tracker to achieve different postures. The specified axis passes through the specified reference object and is the midpoint between the lens node of the first camera and the lens node of the second camera, and the distance from the lens node of the first camera to the specified axis is equal to the distance from the lens node of the second camera to the specified axis.

3. The method of claim 2, wherein, The specified angle is 90°.

4. The method of claim 2, wherein, Acquiring measurement data from the measuring device measuring the same specified reference object in at least two different orientations includes: Acquire measurement data measured by the measuring device in one measurement cycle; wherein, the measurement cycle is the period from when the measuring device starts rotating from the initial pose until it returns to the initial pose; the measurement cycle includes the initial pose and at least one intermediate pose obtained by rotating the measuring device relative to the specified axis by a specified angle; the intermediate pose is different from the initial pose.

5. The method of claim 4, wherein, The method further includes: calculating the deviation distance between the coordinate data of the initial pose of the measuring device at the beginning of the measurement cycle and the coordinate data of the device at the beginning pose at the end of the measurement cycle; Based on the coordinate data corresponding to the at least two different poses, the accuracy evaluation information of the three-dimensional reconstruction system is generated, including: when the deviation distance is not greater than a specified deviation distance threshold, the accuracy evaluation information of the three-dimensional reconstruction system is generated based on the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose included in the measurement cycle.

6. The method according to claim 5, characterized in that, The method further includes: If the deviation distance is greater than the specified deviation distance threshold, the coordinate data corresponding to the starting pose and the coordinate data corresponding to the intermediate pose included in the measurement cycle are discarded.

7. The method of claim 5, wherein, If the deviation distance is not greater than a specified deviation distance threshold, the accuracy evaluation information of the three-dimensional reconstruction system is generated based on the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose included in the measurement cycle, including: The first coordinate range between the coordinate data corresponding to the initial pose and the coordinate data corresponding to the intermediate pose during the measurement cycle is statistically analyzed; wherein, the first coordinate range is used as an evaluation of the transformation error from the measurement data in the 3D reconstruction system to the coordinate system of the tracker; the accuracy evaluation information includes the transformation error.

8. The method of claim 1, wherein, The surface of the measuring device is provided with tracking markers; the measuring device has at least two different postures, including: keeping the measuring device facing the tracking markers of the tracker unchanged, changing the distance between the measuring device and the designated reference object, so that the measuring device is in a different posture; or, keeping the measuring device facing the tracking markers of the tracker unchanged, and rotating around the designated reference object, so that the measuring device is in a different posture.

9. The method of claim 8, wherein, Based on the coordinate data corresponding to the at least two different poses, accuracy evaluation information for the 3D reconstruction system is generated, including: The second coordinate range of the coordinate data corresponding to the at least two different attitudes is statistically analyzed; wherein the second coordinate range is used as an evaluation of the equipment error of the measuring device; the accuracy evaluation information includes the equipment error.

10. The method of claim 1, wherein, The designated reference point is a fixed marker point set on a horizontal plane.

11. An electronic device, comprising: The electronic device includes a memory and a processor, wherein the memory stores at least one computer program, which is loaded and executed by the processor to implement the method as described in any one of claims 1 to 10.

12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one computer program, which, when executed by a processor, is capable of implementing the method as described in any one of claims 1 to 10.

13. A computer program product, characterized in that, The computer program product is used to implement the method as described in any one of claims 1 to 10.

Images