A multi-angle structured light stereo detection method and device
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING BOVISION TECH CO LTD
- Filing Date
- 2026-04-07
- Publication Date
- 2026-06-30
Smart Images
Figure CN122305974A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of structural measurement technology, and in particular to a multi-angle structured light stereoscopic detection method and device. Background Technology
[0002] Structured light 3D cameras use a projector to project a pre-designed pattern with a special structure onto the surface of the object to be measured. Then, the camera observes the deformation of the pattern on the surface. If the object surface is a plane, the observed pattern is similar to the projected pattern and there is no deformation. Once the surface has changes in height, the projected pattern will be modulated by the height information. By analyzing this deformation information, the structured light 3D camera can reconstruct the 3D shape.
[0003] To acquire accurate 3D information, structured light 3D cameras typically use monochrome CMOS sensors in high-precision applications, while the optical engine projects stripes of a fixed wavelength onto the object's surface. However, when a complete reconstruction of the object's 3D shape is required, it is often necessary to rotate the object or take multiple shots with the structured light camera, followed by combining the images. This process is slow and introduces motion errors.
[0004] The present invention employs a method of distributing multiple structured light cameras and distinguishing the projection wavelengths, while also matching appropriate narrowband filters to ensure simultaneous triggering of acquisition and simultaneous reconstruction of results without interference, and avoids superposition of motion errors. Summary of the Invention
[0005] This invention provides a multi-angle structured light stereo detection method, comprising: Step 1: Based on the physical parameters of the multi-angle structured light stereo detection device, design four sets of spatiotemporally related coding patterns, and transmit the designed coding patterns to the corresponding structured light cameras respectively. Step 2: Control the structured light camera to project the received coded patterns onto the surface of the object being measured, and simultaneously acquire the coded projection image modulated by the object height. Step 3: Using a multi-channel joint demodulation algorithm, the four sets of coded projection images acquired are simultaneously reconstructed in three dimensions, and after fusion, a complete three-dimensional model of the object under test is obtained.
[0006] The multi-angle structured light stereo detection method described above involves designing four sets of spatiotemporally correlated coded patterns based on the physical parameters of the multi-angle structured light stereo detection device, and transmitting the designed coded patterns to the corresponding structured light cameras. The method comprises the following sub-steps: The geometric layout, optical wavelength configuration, and hardware characteristics of the multi-angle structured light stereo detection equipment are parameterized to obtain the design parameter set; Based on the design parameter set, independent coded pattern generation functions are constructed for the four structured light cameras; For each time frame t, four coded pattern generation functions are synchronously invoked, and the generated patterns are transmitted to the corresponding four structured light cameras.
[0007] The multi-angle structured light stereo detection method described above, wherein the multi-channel joint demodulation algorithm utilizes four independent channels to process four sets of coded projection images in parallel, and the specific data processing flow within each channel is as follows: Perform phase demodulation on the i-th group of coded projection images and extract its corresponding absolute phase map; Using a pre-built phase difference-height mapping function, the local height value corresponding to each pixel in the absolute phase map is calculated, and the three-dimensional coordinates of the object are calculated based on the local height value. After sorting, the result is output as the i-th point cloud.
[0008] The multi-angle structured light stereo detection method described above, wherein the multi-channel joint demodulation algorithm further includes: The point clouds output from the four channels are stitched together into a total point cloud containing redundancy. After removing the redundant points, the total point cloud is converted into a complete 3D model of the object being measured.
[0009] The present invention also provides a multi-angle structured light stereoscopic detection device, comprising: a stage, four structured light cameras and a central processing unit; the stage is a horizontally placed platform for supporting the object to be measured; the four structured light cameras are evenly distributed around the stage, and the light source wavelengths used are 405nm, 450nm, 550nm and 630nm respectively; the central processing unit is electrically connected to the four structured light cameras to execute the multi-angle structured light stereoscopic detection method described above.
[0010] The multi-angle structured light stereoscopic detection device described above has a projection component (1) and an imaging component (2) integrated inside each structured light camera. The projection component (1) is used to project a preset coded pattern. Its optical path is as follows: the DLP light source (11) projects light of a specific wavelength onto the digital micro-reflector (12). The digital micro-reflector (12) modulates the incident light according to the preset coded pattern, and then shapes it through the optomechanical lens (13) and filters it through the narrow-band filter (14) at the projection end before projecting it onto the surface of the object being measured. The imaging component (2) is used to acquire the encoded projection image after the height modulation and deformation of the object under test. Its optical path is as follows: the reflected light from the surface of the object under test is filtered by the narrow band filter (23) at the imaging end and then converged by the lens (22) onto the CMOS monochrome sensor (21). The center wavelengths of the narrowband filter (14) at the projection end and the narrowband filter (23) at the imaging end are consistent with the wavelength projected by the DLP light source (11).
[0011] The beneficial effects achieved by this invention are as follows: by arranging multiple structured light cameras in an array, three-dimensional images of objects can be quickly acquired, avoiding errors caused by motion; each structured light camera uses a different wavelength light source, a corresponding narrowband filter, and a unique coding pattern, avoiding mutual interference caused by simultaneous operation. Attached Figure Description
[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.
[0013] Figure 1 This is a flowchart of a multi-angle structured light stereo detection method provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of a multi-angle structured light stereoscopic detection device provided in Embodiment 2 of this application; Figure 3 This is a schematic diagram of a structured light camera provided in Embodiment 2 of this application. Detailed Implementation
[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0015] Example 1 like Figure 1 As shown, Embodiment 1 of this application provides a multi-angle structured light stereo detection method, including: Step S10: Based on the physical parameters of the multi-angle structured light stereo detection device, design four sets of spatiotemporally correlated coding patterns, and transmit the designed coding patterns to the corresponding structured light cameras respectively; The multi-angle structured light stereoscopic detection equipment possesses unique physical parameters, including its spatial geometric layout, optical wavelength configuration, and hardware characteristics. Based on these physical parameters, four sets of spatiotemporally correlated coding patterns are designed, specifically through the following sub-steps: Step S11: Parametrically configure the geometric layout, optical wavelength configuration, and hardware characteristics of the multi-angle structured light stereoscopic inspection equipment to obtain the design parameter set; The design parameter set is divided into two categories: spatial geometric parameters and optical and hardware parameters. The spatial geometric parameters are obtained by parameterizing the geometric layout of the multi-angle structured light stereoscopic detection device, and include: a global coordinate system, a three-dimensional coordinate system established with the center of the stage (the area where the object to be measured is expected to be placed) as the origin; and a projection center, representing the three-dimensional coordinates of the projection optical center (optical center of the projection component) of the i-th structured light camera in the global coordinate system, denoted as a vector. The imaging center, representing the three-dimensional coordinates of the i-th imaging optical center (the optical center of the imaging component) in the global coordinate system, is denoted as a vector. The baseline vector is the line connecting the i-th projection center and the imaging center. Its length is called the baseline distance, denoted as . ; Direction vector, representing the direction of the principal optical axis of the i-th structured light camera (by... (pointing to the origin of the global coordinate system), denoted as , called the projection direction vector, and the imaging principal optical axis direction of the i-th structured light camera (given by...). (pointing to the origin of the global coordinate system), denoted as This is called the imaging direction vector; The optical and hardware parameters are obtained through the parameterized optical wavelength configuration and hardware characteristics of the multi-angle structured light stereoscopic inspection device, including: projection wavelength, which characterizes the light source wavelength used by each structured light camera, denoted as... (405nm, 450nm, 550nm, 630nm respectively); reference plane homography matrix, the projection transformation matrix from the projected image plane of each structured light camera to the reference plane (global coordinate system z=0 plane) obtained through calibration. .
[0016] Step S12: Based on the design parameter set, construct independent coded pattern generation functions for the four structured light cameras; A separate coded pattern generation function is constructed for each structured light camera to generate a unique coded pattern. This function comprises two parts: a spatial basis pattern function and a temporal phase modulation function. The spatial basis pattern function generates a cosine fringe pattern with grayscale values in the range [0,1], and both its frequency and direction vary spatially. Specifically: For the i-th structured light camera, the goal for each pixel (x, y) on the projected image plane is to generate a locally optimal fringe on the reference plane. To this end, a two-dimensional frequency vector is defined. ,in
[0017] This represents the reference fringe period preset at the center point O of the reference plane for the reference wavelength. Let i be the projection center of the i-th structured light camera. The current pixel's (x, y) 3D coordinates on the reference plane are obtained through the homography matrix of the reference plane. Transform it onto the reference plane to obtain, The reference wavelength is selected (any light source wavelength used by the structured light camera can be chosen as the reference; in this embodiment, 550nm is used). The wavelength of the light source used by the i-th structured light camera;
[0018] They are vectors Component values in the X and Y directions, , and These are the projection and imaging direction vectors of the i-th structured light camera, respectively. Is the reference plane in The normal vector at the point; Based on the above frequency vector The constructed spatial basis pattern function Represented as:
[0019] in It is the coordinate vector (two-dimensional) after the projection plane coordinates (x, y) are mapped to the reference plane. The term is used to linearly map the range of the cosine function from [-1,1] to the grayscale range of [0,1] that the physical projection device can receive; Timing phase modulation function The phase modulation of the generated fringe pattern is then performed using the coupled wavelength and baseline information, and its mathematical expression is:
[0020] t is the discrete time frame number, ranging from 0 to N-1, and N is the total length of the projected pattern sequence. Let be the wavelength of the light source used by the i-th structured light camera. The sum of the wavelengths of the light sources used by the four structured light cameras. This represents the baseline distance of the i-th structured light camera. The maximum baseline distance among the four structured light cameras. Let be the modulation frequency increment of the i-th structured light camera. , The average baseline distance of the four structured light cameras. The adjustment index (value 1~2) is used. A fixed initial phase offset is used to ensure that the initial phases of the four structured light cameras are uniformly distributed on the unit circle at time t=0, forming a natural orthogonal basis; Spatial basis pattern function With timing phase modulation function By combining these methods, a unique coded pattern generation function for the i-th structured light camera is constructed. , is represented as: Step S13: For each time frame t, synchronously call four coded pattern generation functions and transmit the generated patterns to the corresponding four structured light cameras.
[0021] Step S20: Control the structured light camera to project the received coded patterns onto the surface of the object being measured, and simultaneously acquire the coded projection image modulated by the object height; A synchronization trigger signal is sent to four structured light cameras. Each camera, according to a preset frame order (t=0,1,……,N-1), synchronously projects its received coded pattern onto the surface of the object under test and acquires the coded projection image, which is deformed after being highly modulated by the object's surface. The t-th frame image acquired by the i-th structured light camera is denoted as... ,in These are the coordinates of the camera image plane.
[0022] Step S30: Using a multi-channel joint demodulation algorithm, three-dimensional reconstruction is performed simultaneously on the four sets of coded projection images acquired, and the fusion results in a complete three-dimensional model of the object under test. The multi-channel joint demodulation algorithm uses four independent channels to process four sets of coded projection images in parallel. The specific data processing flow within the i-th channel is as follows: Step S31: Perform phase demodulation on the acquired i-th group of coded projection images and extract its corresponding absolute phase map; For the i-th group of coded projection images, image preprocessing is first performed, including noise reduction and grayscale normalization. Then, a demodulator is used to process each pixel. The grayscale value sequence is demodulated, and its corresponding absolute phase value is extracted. This ultimately yields an absolute phase diagram; the demodulator is based on the aforementioned timing phase modulation function. The orthogonality design is expressed mathematically as follows:
[0023] t takes values from 0 to N-1, where N is the length of the acquired image sequence. For the i-th group of encoded projection images, the t-th frame image is... It is the imaginary unit. It is a demodulated signal in complex form. To take complex angle functions.
[0024] Step S32: Using the pre-constructed phase difference-height mapping function, calculate the local height value corresponding to each pixel in the absolute phase map, and calculate the three-dimensional coordinates of the object based on the local height value. After sorting, output the i-th point cloud. The construction process of the phase difference-height mapping function is as follows: Move the calibration plate to multiple positions along a direction perpendicular to the reference plane (Z-axis direction) with a fixed step size (e.g., 0.1 mm); At each calibration plate height Next, the complete pattern projection and image acquisition process is executed (steps S10-S20), and the acquired image is phase demodulated (step S31) to obtain the image of each pixel on the calibration plate surface at the i-th camera image plane at that height. Corresponding absolute phase value ; For each pixel Calculate its position at the height of the calibration plate. The phase value when the calibration plate is on the reference plane (z=0) is the same as the phase value when the calibration plate is on the reference plane. difference ,Right now ; The obtained data pairs Perform curve fitting to establish a curve based on phase difference. Mapping function to height Z .
[0025] Using the constructed phase difference-height mapping function, the local height value corresponding to each pixel in the absolute phase map is calculated, and the three-dimensional coordinates of the object are calculated from the local height value. The specific steps are as follows: ① Calculate the phase difference between each pixel in the current phase map and the reference plane phase map; Perform a complete pattern projection and image acquisition process on the reference plane (steps S10-S20), and perform phase demodulation on the acquired image (step S31) to obtain the absolute phase map of the reference plane. Then, use the formula... Calculate the phase difference between each pixel in the current phase map and the reference plane phase map. ,in For the pixel in the current phase image The absolute phase value at that point, For the pixel points in the reference plane phase map The absolute phase value at that point.
[0026] ② Substitute the calculated phase difference into the phase difference-height mapping function in sequence to calculate the local height value corresponding to each pixel; The local height value corresponding to each pixel is denoted as ,but .
[0027] ③ Calculate the three-dimensional coordinates of each pixel in the global coordinate system based on the local height value; For each pixel Its corresponding homogeneous coordinates in the camera's normalized coordinate system are marked as follows: Combined with local height values By transforming to the global coordinate system, the three-dimensional coordinates of the pixel can be obtained. The mathematical expression for the transformation process is: ,in Let be the rotation matrix of the i-th structured light camera. For pixels The corresponding local height value, Let be the intrinsic parameter matrix of the i-th structured light camera. The inverse matrix, Let be the translation vector of the i-th structured light camera.
[0028] The three-dimensional coordinates of each pixel are organized into a dataset, denoted as the point cloud set of the i-th coded projection image.
[0029] The point clouds output from the four channels are stitched together into a total point cloud containing redundancy. After removing the redundant points, the total point cloud can be converted into a complete 3D model of the object being measured. The steps for removing redundant points are as follows: Based on the actual size of the object being measured, a three-dimensional cuboid that can completely enclose the object is defined in the global coordinate system as the fusion space. Then, the fusion space is uniformly divided into multiple tiny cubic units, with the side length of each cubic unit being half of the expected average spacing of the point cloud. Traverse the point cloud data within the total point cloud set, and assign it to the corresponding cube cell according to its three-dimensional coordinates. Only one point cloud data is allowed to be assigned to each cube cell. Set a flag for each cube cell, initially set to 0. Iterate through the point cloud data in the total point cloud set, query which cube cell its 3D coordinates fall into, and then check if the flag of that cube cell is 1. If not, set it to 1; if so, remove the current point cloud data from the total point cloud set. This ensures that each cube cell retains only one point cloud data. When all point clouds have been traversed, redundant point clouds have also been removed.
[0030] Example 2 like Figure 2As shown in Embodiment 2 of this application, a multi-angle structured light stereoscopic detection device is provided, including: a stage, four structured light cameras, and a central processing unit; the stage is a horizontally placed platform for supporting the object to be measured; the four structured light cameras are evenly distributed around the stage, and the light source wavelengths used are 405nm, 450nm, 550nm, and 630nm, respectively; the central processing unit is electrically connected to the four structured light cameras to execute a multi-angle structured light stereoscopic detection method.
[0031] refer to Figure 3 Each structured light camera integrates a projection component 1 and an imaging component 2. The projection component 1 is used to project a preset coded pattern. Its optical path is as follows: the DLP light source 11 projects light of a specific wavelength onto the digital micromirror (DMD) 12. The DMD 12 modulates the incident light according to the preset coded pattern, and then the light is shaped by the optomechanical lens 13 and filtered by the projection end narrowband filter 14 before being projected onto the surface of the object being measured. The imaging component 2 is used to acquire the coded projection image after being highly modulated and deformed by the object being measured. Its optical path is as follows: the reflected light from the surface of the object being measured is filtered by the imaging end narrowband filter 23 and then converged by the lens 22 onto the CMOS monochrome sensor 21. The center wavelengths of the projection end narrowband filter 14 and the imaging end narrowband filter 23 are consistent with the wavelength projected by the DLP light source 11, and are used to shield the projection light of other structured light units and ambient stray light.
[0032] The measurement process in this embodiment is as follows: The central processing unit designs four sets of spatiotemporally correlated coding patterns and transmits the designed coding patterns to the corresponding structured light cameras respectively; The structured light camera is controlled to project the received coded patterns onto the surface of the object being measured, and the coded projection image modulated by the height of the object is acquired simultaneously. A multi-channel joint demodulation algorithm is used to simultaneously reconstruct three-dimensional images from four sets of acquired coded projection images, and the fused images yield a complete three-dimensional model of the object under test.
[0033] Corresponding to the above embodiments, the present invention provides a computer storage medium, including: at least one memory and at least one processor; The memory is used to store one or more program instructions; A processor is used to run one or more program instructions to execute a multi-angle structured light stereo detection method.
[0034] Corresponding to the above embodiments, this embodiment of the invention provides a computer-readable storage medium containing one or more program instructions, which are executed by a processor to provide a multi-angle structured light stereo detection method.
[0035] The embodiments disclosed in this invention provide a computer-readable storage medium storing computer program instructions, which, when executed on a computer, cause the computer to perform the aforementioned multi-angle structured light stereoscopic detection method.
[0036] In this embodiment of the invention, the processor can be an integrated circuit chip with signal processing capabilities. 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.
[0037] The various methods, steps, and logic diagrams disclosed in the embodiments of this invention can be implemented or executed. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software modules can reside 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. The processor reads information from the storage medium and, in conjunction with its hardware, completes the steps of the above methods.
[0038] The storage medium can be memory, such as volatile memory or non-volatile memory, or may include both volatile and non-volatile memory.
[0039] Among them, non-volatile memory can 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.
[0040] Volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (Synchlink DRAM, SLDRAM), and direct memory bus RAM (DRRAM).
[0041] The storage media described in the embodiments of the present invention are intended to include, but are not limited to, these and any other suitable types of memory.
[0042] Those skilled in the art will recognize that, in one or more of the examples above, the functions described in this invention can be implemented using a combination of hardware and software. When applied as software, the corresponding functions can be stored in a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any medium that facilitates the transmission of computer programs from one place to another. Storage media can be any available medium that can be accessed by a general-purpose or special-purpose computer.
[0043] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solution of the present invention should be included within the scope of protection of the present invention.
Claims
1. A multi-angle structured light stereo detection method, characterized in that, include: Step 1: Based on the physical parameters of the multi-angle structured light stereo detection device, design four sets of spatiotemporally related coding patterns, and transmit the designed coding patterns to the corresponding structured light cameras respectively. Step 2: Control the structured light camera to project the received coded patterns onto the surface of the object being measured, and simultaneously acquire the coded projection image modulated by the object height. Step 3: Using a multi-channel joint demodulation algorithm, the four sets of coded projection images acquired are simultaneously reconstructed in three dimensions, and after fusion, a complete three-dimensional model of the object under test is obtained.
2. The multi-angle structured light stereo detection method according to claim 1, characterized in that, Based on the physical parameters of the multi-angle structured light stereo detection device, four sets of spatiotemporally correlated coding patterns were designed, and the designed coding patterns were transmitted to the corresponding structured light cameras. The specific steps are as follows: The geometric layout, optical wavelength configuration, and hardware characteristics of the multi-angle structured light stereo detection equipment are parameterized to obtain the design parameter set; Based on the design parameter set, independent coded pattern generation functions are constructed for the four structured light cameras; For each time frame t, four coded pattern generation functions are synchronously invoked, and the generated patterns are transmitted to the corresponding four structured light cameras.
3. The multi-angle structured light stereo detection method according to claim 1, characterized in that, The multi-channel joint demodulation algorithm uses four independent channels to process four sets of coded projection images in parallel. The specific data processing flow within each channel is as follows: Perform phase demodulation on the i-th group of coded projection images and extract its corresponding absolute phase map; Using a pre-built phase difference-height mapping function, the local height value corresponding to each pixel in the absolute phase map is calculated, and the three-dimensional coordinates of the object are calculated based on the local height value. After sorting, the result is output as the i-th point cloud.
4. The multi-angle structured light stereo detection method according to claim 3, characterized in that, The multi-channel joint demodulation algorithm also includes: The point clouds output from the four channels are stitched together into a total point cloud containing redundancy. After removing the redundant points, the total point cloud is converted into a complete 3D model of the object being measured.
5. The multi-angle structured light stereo detection method according to claim 3, characterized in that, The construction process of the phase difference-height mapping function is as follows: The calibration plate is moved to multiple positions along a direction perpendicular to the reference plane with a fixed step size; At each calibration plate height, a complete pattern projection and image acquisition process is executed, and the acquired image is phase demodulated to obtain the absolute phase value of each pixel on the i-th camera image plane at that height. For each pixel, calculate the difference between its phase value when the calibration plate is at different heights and its phase value when the calibration plate is on the reference plane; The obtained height and phase difference data are subjected to curve fitting to establish a mapping function from phase difference to height.
6. The multi-angle structured light stereo detection method according to claim 5, characterized in that, Using the constructed phase difference-height mapping function, the local height value corresponding to each pixel in the absolute phase map is calculated, and the three-dimensional coordinates of the object are calculated from the local height value. The specific steps are as follows: Calculate the phase difference between each pixel in the current phase map and the reference plane phase map; The calculated phase differences are successively substituted into the phase difference-height mapping function to calculate the local height value corresponding to each pixel. The three-dimensional coordinates of each pixel in the global coordinate system are calculated based on the local height value.
7. A multi-angle structured light stereoscopic inspection device, characterized in that, include: The system consists of a platform, four structured light cameras, and a central processing unit; the platform is a horizontally placed platform used to support the object being measured. Four structured light cameras are evenly distributed around the circumference of the stage, and the light source wavelengths used are 405nm, 450nm, 550nm and 630nm respectively; the central processing unit is electrically connected to the four structured light cameras to execute a multi-angle structured light stereo detection method as described in any one of claims 1-6.
8. The multi-angle structured light stereoscopic inspection device according to claim 7, characterized in that, Each structured light camera integrates a projection component (1) and an imaging component (2). The projection component (1) is used to project a preset coded pattern. Its optical path is as follows: the DLP light source (11) projects light of a specific wavelength onto the digital micro-reflector (12). The digital micro-reflector (12) modulates the incident light according to the preset coded pattern, and then shapes it through the optomechanical lens (13) and filters it through the narrow-band filter (14) at the projection end before projecting it onto the surface of the object being measured. The imaging component (2) is used to acquire the encoded projection image after the height modulation and deformation of the object under test. Its optical path is as follows: the reflected light from the surface of the object under test is filtered by the narrow band filter (23) at the imaging end and then converged by the lens (22) onto the CMOS monochrome sensor (21). The center wavelengths of the narrowband filter (14) at the projection end and the narrowband filter (23) at the imaging end are consistent with the wavelength projected by the DLP light source (11).