Multi-projector monocular 3D structured light system and 3D depth measurement method

Abstract

The application provides a multi-projector monocular 3D structured light system and a 3D depth measurement method. The multi-projector monocular 3D structured light system comprises: a first projector configured to project first structured light into a field of view; a second projector configured to project second structured light into the field of view; and an IR camera configured to collect information of the first structured light or information of the second structured light; wherein an optical center of the first projector, an optical center of the second projector and an optical center of the IR camera are arranged on the same plane, and a first distance between the optical center of the first projector and the optical center of the IR camera is smaller than a second distance between the optical center of the second projector and the optical center of the IR camera.

Description

Technical Field

[0001] Embodiments of this disclosure relate to 3D measurement systems, specifically to a multi-projector monocular 3D structured light system and a 3D depth measurement method. Background Technology

[0002] Structured light is a system consisting of a projector and an IR camera. Specific light information (usually infrared light invisible to the human eye, after specific encoding) is projected onto the surface of an object and the background by the projector, and then captured by the IR camera.

[0003] When in operation, the projector projects light with a certain structure, such as stripes of light with contrasting brightness and darkness. If it is projected onto a flat surface, the reflected light will be stripes of the same thickness as the original. If it is projected onto an irregular object (such as a human face), the stripes will change when reflected back from the irregular object. Based on the changes in the light signal caused by the object, the position and depth of the object can be determined, and thus the entire three-dimensional space can be reconstructed.

[0004] In facial recognition applications (such as unlocking smart devices, facial payment, attendance, etc.), structured light is mainly used to obtain the depth information of a face, thereby enabling biometric detection and assisting in facial recognition. Summary of the Invention

[0005] At least one embodiment of this disclosure provides a multi-projector monocular 3D structured light system, comprising:

[0006] A first projector is configured to project a first structured light into the field of view;

[0007] A second projector, configured to project a second structured light into the field of view; and

[0008] An IR camera, configured to acquire information from the first structured light or the second structured light;

[0009] The optical centers of the first projector, the second projector, and the IR camera are all located on the same plane. The first distance between the optical centers of the first projector and the IR camera is less than the second distance between the optical centers of the second projector and the IR camera.

[0010] In one embodiment of this disclosure, the optical centers of the first projector, the second projector, and the IR camera are arranged on a straight line, and the first projector and the second projector are located on the same side of the IR camera.

[0011] In one embodiment of this disclosure, the optical center of the first projector, the optical center of the second projector, and the optical center of the IR camera are arranged on a straight line, and the first projector and the second projector are respectively arranged on both sides of the IR camera.

[0012] In one embodiment of this disclosure, a first projector projects a first structured light in odd-numbered frames, and an IR camera acquires information from the first structured light to obtain a first image;

[0013] The second projector projects a second structured light in even-numbered frames, and the IR camera acquires information from the second structured light to obtain a second image; and

[0014] The IR camera fuses the first and second images to obtain the measurement results.

[0015] In one embodiment of this disclosure, if the depth difference between the first image and the second image is less than or equal to a first threshold, the IR camera uses the depth of the second image as the measurement result.

[0016] In one embodiment of this disclosure, if the depth difference between the first image and the second image is greater than or equal to a first threshold, or if the second image does not contain depth information, the IR camera uses the depth of the first image as the measurement result.

[0017] In one embodiment of this disclosure, the IR camera determines the range of measurement results based on the depth information in the first image, and searches for the depth information of the second image within the range of the measured results.

[0018] In one embodiment of this disclosure, the first projector and the second projector may be the same or different.

[0019] In one embodiment of this disclosure, the power of the first projector and the second projector is adjustable, and the density and brightness of the first structured light projected by the first projector and the second structured light projected by the second projector are adjustable.

[0020] In one embodiment of this disclosure, the multi-projector monocular 3D structured light system further includes a third projector configured to project a third structured light into the field of view of an IR camera. The optical center of the third projector, the optical center of the first projector, the optical center of the second projector, and the optical center of the IR camera are located on the same plane. The third distance between the optical center of the third projector and the optical center of the IR camera is different from both the first distance and the second distance.

[0021] In one embodiment of this disclosure, the third projector may be the same as or different from the first projector and the second projector, and the third structured light projected by the third projector may be the same as or different from the first structured light projected by the first projector and the second structured light projected by the second projector.

[0022] In the multi-projector monocular 3D structured light system provided in this embodiment, by setting a first projector and a second projector with different baselines, the multi-projector monocular 3D structured light system can achieve high measurement accuracy in different depth ranges. By making the baselines of the first projector and the second projector different, different projectors can be selected to project structured light in different measurement ranges, achieving high-precision depth measurement. By making the power of the first projector and the second projector adjustable, and the density and brightness of the projected first and second structured light adjustable, the multi-projector monocular 3D structured light system can be applied to indoor or outdoor environments, as well as outdoor environments where light intensity is not critical.

[0023] At least one embodiment of this disclosure also provides a 3D depth measurement method applicable to the above-described multi-projector monocular 3D structured light system, the 3D depth measurement method comprising:

[0024] The first projector projects the first structured light at odd-numbered frames, and the information of the first structured light is acquired by the IR camera to form the first image.

[0025] The second projector projects the second structured light at even-numbered frames, and the information of the second structured light is acquired by an IR camera to form a second image; and

[0026] The depth information from the first image and the second image are fused to determine the depth measurement result.

[0027] In one disclosed embodiment, fusing depth information from a first image and depth information from a second image to determine the depth measurement result includes:

[0028] When the depth difference between the first image and the second image is small, the depth of the second image is used as the measurement result;

[0029] If the depth difference between the first image and the second image is greater than a first threshold, the depth of the first image is used as the measurement result; and

[0030] If the second image does not contain depth information, the depth of the first image is used as the measurement result.

[0031] In one embodiment of this disclosure, the first projector and the second projector may be the same or different.

[0032] In one embodiment of this disclosure, the power of the first projector and the second projector is adjustable. In response to measuring an ambient light intensity greater than a first light intensity threshold, and determining that the multi-projector monocular 3D structured light system is operating in an outdoor environment, the power of the first projector and the second projector is increased.

[0033] In one embodiment of this disclosure, the power of the first projector and the second projector is adjustable. In response to measuring an ambient light intensity less than a second light intensity threshold, and determining that the multi-projector monocular 3D structured light system is operating in an indoor environment, the power of the first projector and the second projector is reduced.

[0034] In one embodiment of this disclosure, the multi-projector monocular 3D structured light system further includes a third projector, and the method further includes setting the distance between the optical center of the third projector and the optical center of the IR camera to be different from the first distance and the second distance.

[0035] In the 3D depth measurement method according to embodiments of this disclosure, the depth of the object under test is obtained by using structured light modules with different baseline lengths. By utilizing the measurement characteristics of structured light modules with different baseline lengths and fusing images generated by different structured light modules, the depth of the object under test is determined, enabling large-scale, high-precision measurement of the object. Simultaneously, the power of the first and second projectors can be adjusted, allowing the multi-projector monocular 3D structured light system to obtain more accurate measurement results in different lighting environments.

[0036] At least one embodiment of this disclosure also provides an electronic device including the above-described multi-projector monocular 3D structured light system.

[0037] In one embodiment of this disclosure, the electronic device is a mobile phone, a time and attendance machine, an access control system, or a facial recognition payment device. Attached Figure Description

[0038] Figure 1 A schematic diagram of the structured light device measuring profile is shown.

[0039] Figure 2 The diagram schematically illustrates the relationship between depth z and corresponding parallax d for different baseline lengths, given a reference plane distance and a focal length.

[0040] Figure 3 The diagram schematically illustrates the depth difference of 1-pixel parallax at different distances for structured light devices with different baseline lengths.

[0041] Figure 4 The diagram schematically illustrates the measurement results of a face at the same location using structured light equipment with different baseline lengths.

[0042] Figure 5 A schematic diagram of the structure of a multi-projector monocular 3D structured light system according to an embodiment of the present disclosure is shown.

[0043] Figure 6 The diagram schematically illustrates the structure and FOV distribution of a multi-projector monocular 3D structured light system according to an embodiment of the present disclosure. Detailed Implementation

[0044] The present disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present disclosure will become clearer and more apparent.

[0045] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0046] Furthermore, the technical features involved in the different embodiments of this disclosure described below can be combined with each other as long as they do not conflict with each other.

[0047] Monocular structured light refers to structured light that uses only one camera. It typically includes a structured light projector, an IR camera, and an RGB camera. The projector projects light with a specific structure, the IR camera acquires 3D images, and the RGB camera acquires 2D RGB images. Monocular structured light is frequently used in facial recognition applications, such as iPhone's Face ID and facial recognition payment devices.

[0048] Structured light equipment requires factory calibration of its components before leaving the factory, including camera intrinsic and extrinsic parameters, and an IR map (hereinafter referred to as the reference map, typically a planar image at a distance of about 50cm from the camera). During use, the IR camera acquires images containing infrared light. Using the camera's calibration parameters and the reference map, along with appropriate depth calculation algorithms, the depth of each pixel in the current image is calculated. Monocular structured light offers high accuracy at close range, but accuracy decreases with distance. The main factors affecting accuracy include baseline size, projector density, camera parameters, and algorithm scheme.

[0049] Figure 1 A schematic diagram of the measurement profile of a structured light device is shown. (For example...) Figure 1 As shown, the center of the projected light from the IR projector is P, the optical center of the IR camera is C, and the distance from P to C is b, which is called the baseline length. When the structured light device is working, the IR projector, located at a distance from the IR camera, projects structured light (e.g., alternating bright and dark stripes, light spots, etc.) onto the object. The IR camera receives the structured light reflected back from objects at different distances (e.g.,... Figure 1For the same ray PO emitted by the IR projector, passing through point R on the reference plane, the imaging point on the CCD sensor of the IR camera is point R1. For points R1 and K1, this imaging point is actually the projection point of the same ray at different distances. The difference between the positions of this set of matching points is called the parallax d, and the distance from O to the camera plane is called the depth z.

[0050] exist Figure 1 In this case, ΔRKC is similar to ΔR1K1C, therefore:

[0051]

[0052] At the same time, ΔOKR is similar to ΔOCP, therefore:

[0053]

[0054] R1K1 is the parallax d, which is the pixel offset between the current camera image and the reference plane image. Therefore, the depth formula is expressed as:

[0055]

[0056] Where b represents the baseline length, the distance between the IR projector and the IR camera;

[0057] f represents the focal length;

[0058] z0 represents the distance to the reference plane; and

[0059] d represents parallax.

[0060] When calculating depth, the algorithm searches for the offset of the current point in the reference plane, and substitutes it into the above formula to calculate the depth of the current point.

[0061] Figure 2 This illustrates the relationship between depth z and corresponding disparity d for different baseline lengths, given a reference plane distance and a focal length. Figure 2 In this case, the reference plane distance is 500mm, the focal length is 1000mm, and the baseline lengths are 60mm and 100mm respectively. Figure 2 In the diagram, the horizontal axis represents parallax (d) in pixels, and the vertical axis represents distance (z) in mm. From... Figure 2 As can be seen, at close range, the parallax produced by a structured light device with a small baseline length is greater than that produced by a structured light device with a large baseline length. At long range, the parallax produced by a structured light device with a large baseline length is less than that produced by a structured light device with a small baseline length. In other words, the larger the baseline, the smaller the ranging range. Meanwhile, from... Figure 2As can be seen, within the same parallax range (-90, 100), the measurable range of a structured light device with a baseline length of 60mm is 200mm+ to 2000mm, while the measurable range of a structured light device with a baseline length of 100mm is 300mm+ to 900mm.

[0062] Figure 3 In the figure, the horizontal axis z represents the distance in mm, and the vertical axis represents the error in mm. Figure 3 The diagram shows the depth difference of 1-pixel parallax for structured light devices with different baseline lengths at different distances. It can be seen that at 600mm, the error of a 60mm baseline structured light is 5.9mm, while the error of a 100mm baseline structured light is 3.6mm. The higher the accuracy, the higher the single-pixel parallax accuracy of the structured light device with a larger baseline length (100mm), while the single-pixel parallax accuracy of the structured light device with a smaller baseline length (60mm) is lower. It is evident that the larger the baseline, the smaller the error at the same distance.

[0063] Taking a human face at a distance of 800mm as an example, measurements were taken using structured light devices with different baseline lengths. Figure 4 The results show the measurement of a face at the same location using structured light devices with different baseline lengths. Figure 4 The face shown is located at 80mm, and the baseline lengths of the structured light equipment used are 60mm and 100mm, respectively. Figure 4 (a) shows a facial depth point cloud map detected by a structured light device with a baseline length of 100 mm. Figure 4 (b) shows a facial depth point cloud map detected by a structured light device with a baseline length of 60 mm. Figure 4 As can be seen, the structured light device with a baseline length of 100mm detects more detailed facial features; for example, the bridge of the nose is closer to its actual height, and the overall facial detail is higher.

[0064] Based on this, in order to address the problems of small viewing angle of structured light devices with large baseline lengths and low accuracy of structured light devices with small baseline lengths, at least one embodiment of this disclosure provides a multi-projector monocular 3D structured light system, which has a large viewing angle and relatively high accuracy.

[0065] At least one embodiment of this disclosure provides a multi-projector monocular 3D structured light system, comprising: a first projector configured to project a first structured light into a field of view; a second projector configured to project a second structured light into the field of view; and an IR camera configured to acquire information of the first structured light or information of the second structured light; wherein the optical centers of the first projector, the second projector, and the IR camera are arranged on a straight line, and a first distance between the optical centers of the first projector and the IR camera is smaller than a second distance between the optical centers of the second projector and the IR camera.

[0066] Figure 5 A schematic diagram of a multi-projector monocular 3D structured light system according to an embodiment of the present disclosure is shown. The multi-projector monocular 3D structured light system includes a first projector 01, a second projector 02, and an IR camera 00. The optical centers of the first projector 01, the second projector 02, and the IR camera 00 are located on the same straight line. A first distance between the optical center of the IR camera 00 and the optical center of the first projector 01 is a first baseline 03 of the first projector 01, and the first projector 01 and the IR camera 00 form a first structured light module with the first baseline 03. A second distance between the optical center of the IR camera 00 and the optical center of the second projector 02 is a second baseline 04 of the second projector 02, and the second projector 02 and the IR camera 00 form a second structured light module with the second baseline 04. The first distance is less than the second distance. The first projector 01 is configured to project first structured light into the field of view of the IR camera, and the IR camera is configured to collect the first structured light within its field of view. The second projector 02 is configured to project a second structured light into the field of view of the IR camera, and the IR camera is configured to collect the second structured light within the field of view.

[0067] Figure 5 The structure of a multi-projector monocular 3D structured light system according to an embodiment of the present disclosure is described using the example of the first projector 01 and the second projector 02 being disposed on one side of an IR camera. However, the structure of the multi-projector monocular 3D structured light system according to an embodiment of the present disclosure is not limited thereto. In some embodiments of the present disclosure, the first projector 01 and the second projector 02 may be disposed on opposite sides of the IR camera, and the optical centers of the first projector 01, the second projector 02, and the IR camera are located on a straight line. The distance between the optical center of the first projector 01 and the optical center of the IR camera is less than the distance between the optical center of the second projector 02 and the optical center of the IR camera.

[0068] from Figure 5 and Figure 6As can be seen, because the first projector 01 is relatively close to the IR camera, the overlap between the first structured light projected by the first projector 01 and the IR camera's field of view (FOV) is relatively large, making it suitable for depth calculations within a larger viewing angle. Conversely, because the second projector 02 is relatively far from the IR camera, the overlap between the second structured light projected by the second projector 02 and the IR camera's FOV is relatively small, making it suitable for depth calculations within a smaller viewing angle but at relatively greater distances. Furthermore, because the second baseline of the second projector 02 is relatively long, it achieves higher accuracy at relatively greater distances.

[0069] When operating the multi-projector monocular 3D structured light system according to the embodiments of the present disclosure, the first projector 01 and the second projector 02 work alternately. The IR camera acquires information of the first structured light projected by the first projector 01 in odd-numbered frames to obtain a first image. The IR camera acquires information of the second structured light projected by the second projector 02 in even-numbered frames to obtain a second image. The IR camera fuses the first image and the second image to obtain a measurement result.

[0070] In one embodiment of this disclosure, if the depth difference between the first image and the second image is less than or equal to a first threshold, i.e., the depth difference between the first image and the second image is small, the depth of the second image is used as the measurement result. In one embodiment of this disclosure, if the depth difference between the first image and the second image is greater than the first threshold, the depth of the first image is used as the measurement result. In one embodiment of this disclosure, if the second image does not contain depth information, the depth of the first image is used as the measurement result.

[0071] The first image is obtained by the IR camera 00 when the first structured light is projected by the first projector 01. The length of the first baseline 03 is relatively small, and the first image has the characteristics of a large viewing angle and low precision. The second image is obtained by the IR camera 00 when the second structured light is projected by the second projector 02. The length of the second baseline 04 is relatively large, and the second image has the characteristics of a small viewing angle and high precision.

[0072] When the difference in depth information between the first image and the second image is small, that is, in Figure 2 Of the two curves shown, the closer they are, the more suitable the distance between the measured object and the imaging plane of the IR camera is. Figure 2 In regions where the two curves are relatively close together, the second image is used as the measurement result due to its high precision.

[0073] When the depth information of the first image and the second image differs significantly, that is, in Figure 2In the two curves shown, the greater distance between them indicates a larger distance between the measured object and the imaging plane of the IR camera. In this case, if... Figure 2 The upper right portion is shown in the image. At this point, since the first image is suitable for determining depth information within a larger field of view, it is used as the measurement result.

[0074] If the first image contains depth information but the second image does not, it can be determined that the angle between the measured object and the imaging plane of the IR camera is too large, resulting in the lack of depth information in the second image. In this case, since the first image is suitable for determining depth information within a larger viewing angle, the first image is used as the measurement result.

[0075] Since the first image has a larger measurement range and the second image has higher measurement accuracy, in another embodiment of this disclosure, the range of measurement results is determined based on the depth information in the first image, and the depth information in the second image is searched within this range as the measurement result. For example, if the distance between the measured object and the IR camera is determined to be approximately 50cm based on the depth information in the first image, the depth information in the second image is searched only within a range centered on 50cm, for example, the depth information within the range of 47cm to 53cm, to quickly determine the depth information of the measured object.

[0076] In one embodiment of this disclosure, the first projector and the second projector are identical. The first projector and the second projector being identical means that the first projector and the second projector have the same power, and that the first structured light projected by the first projector and the second structured light projected by the second projector have the same structure, density, brightness, and power, etc.

[0077] In another embodiment of this disclosure, the first projector and the second projector are different. To achieve a more distant and higher-precision 3D effect, the power of the second projector is greater than that of the first projector, the density of the second structured light projected by the second projector is greater than that of the first structured light projected by the first projector, and the brightness of the second structured light projected by the second projector is greater than that of the first structured light projected by the first projector.

[0078] In one embodiment of this disclosure, the power of the first projector and the second projector is adjustable, as are the density and brightness of the first structured light projected by the first projector and the second structured light projected by the second projector. By making the power of the first projector and the second projector, and the density and brightness of the first structured light projected by the first projector and the second structured light projected by the second projector, the power of the first projector and the second projector can be set to be lower in indoor environments, and the density and brightness of the first structured light projected by the first projector and the second structured light projected by the second projector can be lower. In outdoor environments, the power of the first projector and the second projector can be set to be higher, and the density and brightness of the first structured light projected by the first projector and the second structured light projected by the second projector can be higher. Outdoors, due to the interference of infrared components in sunlight, the projector needs to project a speckle pattern with higher power to improve the speckle signal-to-noise ratio. Therefore, in outdoor environments, in response to a higher measured ambient light intensity, a projector with higher power and higher brightness can be used. Furthermore, to achieve a higher signal-to-noise ratio, the density of the first structured light and the second structured light can be appropriately reduced, sacrificing long-distance performance to improve outdoor usability.

[0079] In one embodiment of this disclosure, the multi-projector monocular 3D structured light system further includes a third projector configured to project third structured light into the field of view of an IR camera. The optical center of the third projector, the optical centers of the first and second projectors, and the optical center of the IR camera are located on the same plane. The third distance between the optical center of the third projector and the optical center of the IR camera is different from both the first and second distances. The third projector and the IR camera form a third structured light module. When the third projector projects the third structured light, the IR camera is also configured to acquire information about the third structured light.

[0080] In a multi-projector monocular 3D structured light system that includes a third projector, high-precision depth measurement can be achieved at different measurement distances by making the first, second, and third distances different, and by ensuring that the first, second, and third baselines are all identical. The third projector can be the same as or different from the first and second projectors.

[0081] The fact that the third projector is the same as the first and second projectors means that the third projector has the same power as the first and second projectors, and that the third structured light projected by the third projector has the same structure, density, and brightness as the first structured light projected by the first projector and the second structured light projected by the second projector.

[0082] The difference between the third projector and the first and second projectors refers to the fact that the third projector has different power, and the third structured light projected by the third projector has different structure, density, and brightness compared to the first structured light projected by the first projector and the second structured light projected by the second projector.

[0083] In the multi-projector monocular 3D structured light system provided in this embodiment, by setting a first projector and a second projector with different baselines, the multi-projector monocular 3D structured light system can achieve high measurement accuracy in different depth ranges. By making the baselines of the first projector and the second projector different, different projectors can be selected to project structured light in different measurement ranges, achieving high-precision depth measurement. By making the power of the first projector and the second projector adjustable, and the density and brightness of the projected first and second structured light adjustable, the multi-projector monocular 3D structured light system can be applied to indoor or outdoor environments, as well as outdoor environments where light intensity is not critical.

[0084] At least one embodiment of this disclosure also provides a 3D depth measurement method applicable to the aforementioned multi-projector monocular 3D structured light system, the 3D depth measurement method comprising:

[0085] The first projector projects the first structured light at odd-numbered frames, and the information of the first structured light is acquired by the IR camera to form the first image.

[0086] The second projector projects the second structured light at even-numbered frames, and the information of the second structured light is acquired by an IR camera to form a second image; and

[0087] The depth information from the first image and the second image are fused to determine the depth measurement result.

[0088] The first distance between the optical center of the first projector and the optical center of the IR camera is smaller than the second distance between the optical center of the second projector and the optical center of the IR camera. Therefore, the first structured light module formed by the first projector and the IR camera is suitable for large-angle, low-precision measurements, while the second structured light module formed by the second projector and the IR camera is suitable for small-angle, high-precision measurements.

[0089] In one embodiment of this disclosure, fusing the depth information of the first image and the depth information of the second image to determine the depth measurement result includes: when the depth difference between the first image and the second image is small, using the depth of the second image as the measurement result.

[0090] In one embodiment of this disclosure, fusing depth information from a first image and depth information from a second image to determine a depth measurement result includes: if the depth difference between the first image and the second image is greater than a first threshold, then using the depth of the first image as the measurement result.

[0091] In one embodiment of this disclosure, fusing depth information from a first image and depth information from a second image to determine a depth measurement result includes: if the second image does not contain depth information, using the depth of the first image as the measurement result.

[0092] In order to quickly determine the depth of the object being measured, in one embodiment of this disclosure, the range of values ​​for the measurement result is determined based on the depth information in the first image, and the depth information of the second image is searched within the range of values.

[0093] In one embodiment of this disclosure, the first projector and the second projector are identical. The first projector and the second projector being identical means that the first projector and the second projector have the same power, and that the first structured light projected by the first projector and the second structured light projected by the second projector have the same structure, density, brightness, and power, etc.

[0094] In another embodiment of this disclosure, the first projector and the second projector are different. To achieve a more distant and higher-precision 3D effect, the power of the second projector is greater than that of the first projector, the density of the second structured light projected by the second projector is greater than that of the first structured light projected by the first projector, and the brightness of the second structured light projected by the second projector is greater than that of the first structured light projected by the first projector.

[0095] In one embodiment of this disclosure, the power of the first projector and the second projector is adjustable. In response to measuring an ambient light intensity greater than a first light intensity threshold, and determining that the multi-projector monocular 3D structured light system is operating in an outdoor environment, the power of the first projector and the second projector is increased.

[0096] In one embodiment of this disclosure, the power of the first projector and the second projector is adjustable. In response to measuring an ambient light intensity less than a second light intensity threshold, and determining that the multi-projector monocular 3D structured light system is operating in an indoor environment, the power of the first projector and the second projector is reduced.

[0097] In one embodiment of this disclosure, the multi-projector monocular 3D structured light system further includes a third projector, and the method further includes setting the distance between the optical center of the third projector and the optical center of the IR camera to be different from the first distance and the second distance.

[0098] In the 3D depth measurement method according to embodiments of this disclosure, the depth of the object under test is obtained by using structured light modules with different baseline lengths. By utilizing the measurement characteristics of structured light modules with different baseline lengths and fusing images generated by different structured light modules, the depth of the object under test is determined, enabling large-scale, high-precision measurement of the object. Simultaneously, the power of the first and second projectors can be adjusted, allowing the multi-projector monocular 3D structured light system to obtain more accurate measurement results in different lighting environments.

[0099] In the description of this disclosure, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "back", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this disclosure, and are only for the convenience of describing this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure.

[0100] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this disclosure based on the specific circumstances.

[0101] The present disclosure has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present disclosure based on these embodiments, all of which fall within the protection scope of the present disclosure.

Claims

1. A multi-projector monocular 3D structured light system, characterized in that, include: A first projector is configured to project a first structured light into the field of view; The second projector is configured to project a second structured light into the field of view; as well as An IR camera, configured to acquire information of the first structured light or the second structured light; The optical centers of the first projector, the second projector, and the IR camera are all located on the same plane. The first distance between the optical centers of the first projector and the IR camera is less than the second distance between the optical centers of the second projector and the IR camera.

2. The multi-projector monocular 3D structured light system according to claim 1, characterized in that, The optical centers of the first projector, the second projector, and the IR camera are aligned on a straight line, and the first and second projectors are located on the same side of the IR camera.

3. The multi-projector monocular 3D structured light system according to claim 1, characterized in that, The optical centers of the first projector, the second projector, and the IR camera are aligned on a straight line, with the first and second projectors positioned on opposite sides of the IR camera.

4. The multi-projector monocular 3D structured light system according to claim 1, characterized in that, The first projector projects the first structured light in odd-numbered frames, and the IR camera collects the information of the first structured light to obtain the first image; The second projector projects the second structured light in even-numbered frames, and the IR camera collects the information of the second structured light to obtain the second image; as well as The IR camera fuses the first and second images to obtain the measurement results.

5. The multi-projector monocular 3D structured light system according to claim 4, characterized in that, If the depth difference between the first image and the second image is less than or equal to a first threshold, the IR camera uses the depth of the second image as the measurement result.

6. The multi-projector monocular 3D structured light system according to claim 4, characterized in that, If the depth difference between the first image and the second image is greater than or equal to a first threshold, or if the second image does not contain depth information, the IR camera will use the depth of the first image as the measurement result.

7. The multi-projector monocular 3D structured light system according to claim 4, characterized in that, The IR camera determines the range of measurement results based on the depth information in the first image, and searches for the depth information in the second image within the range of the measured results.

8. The multi-projector monocular 3D structured light system according to any one of claims 1 to 7, characterized in that, The first projector and the second projector have the same power. The first structured light projected by the first projector and the second structured light projected by the second projector have the same structure, density, brightness and power. Alternatively, the power of the second projector is greater than that of the first projector, the density of the second structured light projected by the second projector is greater than that of the first structured light projected by the first projector, and the brightness of the second structured light projected by the second projector is greater than that of the first structured light projected by the first projector.

9. The multi-projector monocular 3D structured light system according to any one of claims 1 to 7, characterized in that, The power of the first projector and the second projector is adjustable, and the density and brightness of the first structured light projected by the first projector and the second structured light projected by the second projector are adjustable.

10. The multi-projector monocular 3D structured light system according to any one of claims 1 to 7, characterized in that, It also includes a third projector configured to project a third structured light into the field of view of the IR camera. The optical center of the third projector, the optical center of the first projector, the optical center of the second projector, and the optical center of the IR camera are located on the same plane. The third distance between the optical center of the third projector and the optical center of the IR camera is different from the first distance and the second distance.

11. A 3D depth measurement method, applicable to the multi-projector monocular 3D structured light system of claim 1, characterized in that, The 3D depth measurement method includes: The first projector projects the first structured light at odd-numbered frames, and the information of the first structured light is acquired by the IR camera to form the first image. The second projector projects the second structured light at even-numbered frames, and the information of the second structured light is acquired by an IR camera to form a second image; and The depth information from the first image and the second image are fused to determine the depth measurement result.

12. The 3D depth measurement method according to claim 11, characterized in that, By fusing the depth information from the first image and the depth information from the second image, the depth measurement results are determined as follows: When the depth difference between the first image and the second image is small, the depth of the second image is used as the measurement result; If the depth difference between the first image and the second image is greater than a first threshold, the depth of the first image is used as the measurement result; and If the second image does not contain depth information, the depth of the first image is used as the measurement result.

13. The 3D depth measurement method according to claim 11 or 12, characterized in that, The first projector and the second projector have the same power. The first structured light projected by the first projector and the second structured light projected by the second projector have the same structure, density, brightness and power. Alternatively, the power of the second projector is greater than that of the first projector, the density of the second structured light projected by the second projector is greater than that of the first structured light projected by the first projector, and the brightness of the second structured light projected by the second projector is greater than that of the first structured light projected by the first projector.

14. The 3D depth measurement method according to claim 11 or 12, characterized in that, The power of the first and second projectors is adjustable. In response to the measurement of ambient light intensity greater than the first light intensity threshold, it is determined that the multi-projector monocular 3D structured light system is working in an outdoor environment, and the power of the first and second projectors is increased.

15. The 3D depth measurement method according to claim 11 or 12, characterized in that, The power of the first and second projectors is adjustable. In response to the measurement of ambient light intensity less than the second light intensity threshold, it is determined that the multi-projector monocular 3D structured light system is working in an indoor environment, and the power of the first and second projectors is reduced.

16. The 3D depth measurement method according to claim 11, characterized in that, The multi-projector monocular 3D structured light system further includes a third projector, and the method further includes setting the distance between the optical center of the third projector and the optical center of the IR camera to be different from the first distance and the second distance.

17. An electronic device, characterized in that, Includes the multi-projector monocular 3D structured light system as described in claim 1.

18. The electronic device according to claim 17, characterized in that, The electronic device is a mobile phone, attendance machine, access control system, or facial recognition payment device.

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