Three-dimensional measurement method and system based on event camera

Abstract

The invention relates to the technical field of three-dimensional measurement, and discloses a three-dimensional measurement method and system based on an event camera. The three-dimensional measurement method and system based on the event camera comprises the following steps: placing a calibration target in a measurement space, and combining internal and external parameters of the event camera to obtain a target space position; shifting positive and negative Gray codes are projected on the calibration target, and the event camera records brightness change to obtain event information; decoding the shift positive and negative Gray codes according to the event information, and combining internal and external parameters of the event camera to obtain system calibration parameters; the shift positive and negative Gray codes are projected in an actual measurement scene, the shift positive and negative Gray codes are decoded according to event information recorded by the event camera in the actual measurement scene, and the three-dimensional surface shape of the measured object is obtained in combination with system calibration parameters. A three-dimensional measurement system based on an event camera includes an event camera, a projection unit, and a data processing device. According to the scheme, the event camera can be conveniently and effectively utilized to carry out three-dimensional reconstruction on the measured object.

Description

Technical Field

[0001] The present invention relates to the field of three-dimensional measurement technology, and in particular to a three-dimensional measurement method and system based on an event camera. Background Art

[0002] Optical three-dimensional measurement technology has been widely used in intelligent detection, biomedicine, virtual reality and other fields due to its advantages such as non-contact and high precision. However, there are still challenges in achieving accurate measurement in complex scenes, such as overexposure of the camera due to highly reflective metal surfaces, or low signal-to-noise ratio problems caused by black objects. Many studies have attempted to overcome these limitations: the multi-exposure method is currently the most commonly used high dynamic range (HDR) three-dimensional measurement technology. By changing the camera exposure time, stripe images of different brightness levels in the measured scene are obtained, and then fused into a high signal-to-noise ratio (SNR) stripe pattern according to specific rules for three-dimensional reconstruction; in recent years, deep learning has also been introduced into three-dimensional measurement as a powerful data analysis method to repair degraded structured light patterns or improve the signal-to-noise ratio. However, such methods usually rely on high-quality data sets. When the signal-to-noise ratio of the image captured by the camera is too low or there is severe saturation, its measurement effect may be limited.

[0003] As mentioned above, most existing 3D measurement technologies are based on traditional frame-type CCD / CMOS cameras. However, due to the inherent low dynamic range characteristics of frame-type cameras, they are often difficult to apply directly in HDR scenes and usually require the use of complex image processing algorithms or external auxiliary hardware. To overcome this limitation, event cameras have emerged as a new type of visual sensor. Figure 1 As shown in Figure 1, event cameras capture changes in logarithmic light intensity as a continuous stream of events, significantly reducing bandwidth and latency requirements and enabling a dynamic range far exceeding that of traditional cameras. With these advantages, event cameras are increasingly being used in the field of 3D imaging.

[0004] However, the operating mechanism of event cameras relies on the detection of dynamic changes, and their output is binary event data. This makes traditional camera calibration methods and structured light 3D measurement techniques difficult to directly apply. For camera calibration, existing methods typically estimate camera parameters by incorporating event information associated with a calibration target pattern. These methods can be broadly categorized into two types based on how they incorporate event information: one uses an active target to display a flashing pattern, and the other generates events through the motion of the camera or target. Both of these methods have limitations in practical applications, such as the need for specialized calibration targets or complex motion control, which not only increases operational complexity but also hinders integration with subsequent structured light 3D measurement processes. For 3D reconstruction, research has attempted to adapt line structured light or pattern-based structured light methods to event cameras. For example, one study exploits the intensity variations caused by line structured light scanning to stimulate events, thereby enabling 3D reconstruction associated with the structured light pattern. However, due to the sparsity and binary nature of event data, as well as the interference of noise events, accurately extracting the center of the structured light rays remains a significant challenge. Furthermore, issues such as timestamp jitter further limit improvements in 3D reconstruction accuracy. Therefore, how to fully utilize the characteristics of event cameras and overcome their limitations in data output remains a key challenge in achieving high-precision three-dimensional reconstruction. Summary of the Invention

[0005] The present application discloses a three-dimensional measurement method and system based on an event camera, which can conveniently and effectively use the event camera to perform three-dimensional reconstruction of the measured object.

[0006] In order to solve the above problems, the present invention adopts the following technical solutions: In a first aspect, the present application discloses a three-dimensional measurement method based on an event camera, comprising the following steps: Place the calibration target in the measurement space and obtain the target spatial position by combining the internal and external parameters of the event camera; The calibration target is projected with a shifted positive and negative Gray code, and the event camera records the brightness change to obtain event information; The event information obtained by recording brightness changes of the event camera is decoded into the shifted forward and reverse Gray code, and the system calibration parameters are obtained by combining the internal and external parameters of the event camera; The shifted positive and negative Gray codes are projected on the actual measurement scene, and the shifted positive and negative Gray codes are decoded according to the event information recorded by the event camera in the actual measurement scene. Combined with the system calibration parameters, the three-dimensional surface shape of the measured object is obtained.

[0007] In some embodiments, obtaining the internal and external parameters of the event camera includes the following steps: Generate a reflectivity imaging pattern, and use the reflectivity imaging pattern to focus the event camera so that its clear imaging range covers the measurement space; The calibration targets are placed at different positions in the measurement space. The event camera images the calibration targets at each position and combines the reflectivity imaging pattern to obtain the internal and external parameters of the event camera.

[0008] In some embodiments, the specific method of generating the reflectivity imaging pattern includes the following steps: Changing the illumination of the scene so that the event camera records event information of multiple pixels; The event information generated by each pixel within the set time is accumulated to generate a reflectivity imaging pattern.

[0009] In some embodiments, the specific method of changing the lighting of the scene includes the following steps: A projection unit is used to change the lighting of the scene.

[0010] In some embodiments, the method for generating a shifted forward and reverse Gray code includes the following steps: Generate a forward and reverse Gray code projection sequence and a shifted forward and reverse Gray code projection sequence; The positive and negative Gray code projection sequences and the shifted positive and negative Gray code projection sequences are projected in sequence from low to high according to the coding order, so as to complete the generation of the shifted positive and negative Gray code.

[0011] In some embodiments, a specific method for generating a forward and reverse Gray code projection sequence includes the following steps: Generate a traditional Gray code sequence, perform an inversion operation on each codeword in the traditional Gray code sequence, and generate a corresponding inverse Gray code sequence; The traditional Gray code sequence and the inverse Gray code sequence are alternately combined in the order of code words to form a positive and negative Gray code projection sequence.

[0012] In some embodiments, a specific method for generating a shifted forward and reverse Gray code projection sequence includes the following steps: Perform periodic translation on the traditional Gray code sequence to generate a shifted Gray code sequence; Performing an inversion operation on each codeword in the shifted Gray code sequence to generate a corresponding shifted inverse Gray code sequence; The shifted Gray code sequence and the shifted inverse Gray code sequence are alternately combined in the order of code words to form a shifted forward and reverse Gray code projection sequence.

[0013] In some embodiments, the method of projecting a positive and negative Gray code on a calibration target includes the following steps: Burn the shifted forward and reverse Gray code into the projection unit, and use the projection unit to project the calibration target.

[0014] In some embodiments, a specific method for projecting a shifted forward and reverse Gray code in an actual measurement scene includes the following steps: After extracting the Gray code words of the shifted forward and reverse Gray code at different positions, the spatial position of each pixel is fitted with the Gray code word of the shifted forward and reverse Gray code to obtain a fitting coefficient; The spatial position of the object under measurement in the actual measurement scene is calculated based on the fitting coefficient and the Gray code word of the shifted forward and reverse Gray code.

[0015] In a second aspect, the present application further discloses a three-dimensional measurement system based on an event camera, which is applied to the three-dimensional measurement method based on an event camera in the first aspect, comprising: Event camera, used to record event information based on brightness changes; A projection unit, used to project shifted positive and negative Gray codes and change the illumination of the scene; Data processing equipment for decoding shifted forward and reverse Gray codes.

[0016] The technical solution adopted by the present invention can achieve the following beneficial effects: The present invention proposes a full-link three-dimensional measurement solution based on event cameras, covering the entire process from high-precision camera calibration to three-dimensional reconstruction, aiming to give full play to the advantages of event cameras in complex scenes and achieve robust three-dimensional measurement. In terms of event camera calibration, the reflectivity imaging method based on event information proposed in the present invention overcomes the limitations of the imaging modality of event cameras and effectively bridges the technical disconnect between traditional camera calibration and event camera calibration. In terms of three-dimensional reconstruction, the present invention makes full use of the high sensitivity and responsiveness of event cameras to brightness changes in high dynamic range scenes, combines it with the naturally compatible Gray code projection strategy, and effectively overcomes the accuracy and robustness bottlenecks of traditional methods in event data processing while retaining the advantages of event cameras. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a diagram of the working principle of the event camera; Figure 2 is a schematic diagram of the event-based reflectivity imaging method; Figure 3 It is the result of calibrating the event camera using the reflectivity imaging pattern; Figure 4 It is the event information collected by the projected positive and negative Gray code event camera; Figure 5 It is a schematic diagram of the shift Gray code encoding method; Figure 6 It is the measurement result of the standard ball after the measurement system is calibrated Figure 7 These are the measurement results in normal scenes and HDR scenes; Figure 8 This is a flowchart of a three-dimensional measurement method based on an event camera disclosed in some embodiments of the present application. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0020] The following is combined with Figures 1 to 8 , a three-dimensional measurement method and system based on an event camera provided by this application is described in detail through specific embodiments and application scenarios.

[0021] Some embodiments of the present application provide a three-dimensional measurement method based on an event camera, such as Figure 8 As shown, the following steps are included: S100, placing a calibration target in a measurement space, and obtaining the target spatial position by combining internal and external parameters of the event camera; S200, projecting a shifted positive and negative Gray code onto the calibration target, and an event camera records brightness changes to obtain event information; S300, decoding the shifted forward and reverse Gray code according to the event information obtained from the brightness change recorded by the event camera, and obtaining the system calibration parameters by combining the internal and external parameters of the event camera; S400 , projecting the shifted positive and negative Gray codes on the actual measurement scene, decoding the shifted positive and negative Gray codes according to event information recorded by the event camera in the actual measurement scene, and combining the system calibration parameters to obtain the three-dimensional surface shape of the object being measured.

[0022] This embodiment proposes a full-link three-dimensional measurement solution based on an event camera, covering the entire process from high-precision camera calibration to three-dimensional reconstruction, aiming to give full play to the advantages of event cameras in complex scenes and achieve robust three-dimensional measurement. In terms of event camera calibration, the reflectivity imaging method based on event information proposed in this embodiment overcomes the limitations of the event camera imaging modality and effectively bridges the technical disconnect between traditional camera calibration and event camera calibration. In terms of three-dimensional reconstruction, this embodiment fully utilizes the high sensitivity and responsiveness of event cameras to brightness changes in high dynamic range scenes, and combines it with the naturally compatible Gray code projection strategy. While retaining the advantages of event cameras, it effectively overcomes the accuracy and robustness bottlenecks of traditional methods in event data processing.

[0023] In step S100, obtaining the internal and external parameters of the event camera includes the following steps: S110, generating a reflectivity imaging pattern, and using the reflectivity imaging pattern to focus the event camera so that its clear imaging range covers the measurement space; S120 , placing calibration targets at different positions in the measurement space, imaging the calibration targets at each position using an event camera, and combining the reflectivity imaging pattern to obtain internal and external parameters of the event camera.

[0024] In step S110, the specific method of generating the reflectivity imaging pattern includes the following steps: S111, changing the illumination of the scene so that the event camera records event information of multiple pixels; The event information generated by each pixel within the set time is accumulated to generate a reflectivity imaging pattern.

[0025] Since the event camera only responds to logarithmic changes in brightness, when the change exceeds the threshold C, the camera will output the corresponding event pixel position, timestamp, and event polarity. The threshold condition can be expressed as follows: Where I(t) represents the light intensity received at the pixel at time t. I(t0) represents the light intensity received at the pixel at time t0, immediately before the event. Therefore, when objects and light sources in static scenes are stable, event cameras have difficulty generating valid event information for calibration.

[0026] This embodiment modulates the light source so that the event camera records event information related to the scene reflectivity. Accumulating the number of events per pixel can generate a pattern of similar intensity. The light intensity received by a single pixel in the event camera can be expressed as follows: Where I(t) represents the light intensity received by the pixel at time t, I grepresents the illumination intensity, R represents the reflectivity of the surface at the object space corresponding to that pixel, and f(t) represents the periodically modulated projection light source. For ease of discussion, we define the logarithm of illumination intensity as L(t), i.e., L(t) = log(I(t)).

[0027] According to the imaging mechanism of the event camera, the faster the logarithmic intensity of the light in the scene changes, the more event information is generated. Therefore, the absolute value of the derivative of the logarithmic intensity of the light received at the pixel will directly affect the generation of the event, which can be expressed as follows:

[0028] It's easy to see that, given a stable background light and the same illumination pattern at every point in the scene, the number of events generated within a cycle is proportional to the reflectivity at each point. Leveraging this insight, we can generate a pattern directly related to reflectivity by accumulating the number of events at each pixel within a full cycle.

[0029] in, Figure 2 The paper demonstrates that when the event camera is in focus and out of focus, a phase-shifted fringe pattern is projected onto the scene, and the reflectivity pattern is reconstructed by counting the total number of events at each pixel. The proposed event camera reflectivity imaging method can be used to focus the event camera. Figure 2 (a) is the reflectivity imaging pattern of the calibration target scanned using phase-shifted fringe structured light when the event camera is focused. Figure 2 (b) Reflectivity imaging pattern when the event camera is out of focus.

[0030] In step S111, the specific method for changing the illumination of the scene includes the following steps: S1111. Use a projection unit to change the lighting of the scene.

[0031] In this embodiment, the projection unit plays a key role in the changes in scene lighting conditions, allowing the event camera to obtain event information based on brightness changes. As a preferred embodiment, the event camera used in this embodiment has a resolution of 1280*720 pixels and the projection unit has a resolution of 1920*1080 pixels.

[0032] In steps S110 and S120, after the event camera is focused, a standard calibration target is placed in the measurement space and imaged using the reflectivity imaging method. The target is placed in different positions and imaged repeatedly. Finally, the reflectivity imaging patterns of all calibration targets are used to calculate the intrinsic and extrinsic parameters of the event camera. The calculation method of the intrinsic and extrinsic parameters of the camera can be referred to the calibration method of Z. Zhang (Z. Zhang, "A flexible new technique for camera calibration." IEEE Transactions on pattern analysis and machine intelligence. 22(11), 1330-1334(2000)).

[0033] The internal and external parameters of the event camera include the lens distortion, focal length and position of the event camera in space.

[0034] In step S300, the method for generating the shifted forward and reverse Gray code includes the following steps: S310, generating a positive and negative Gray code projection sequence and a shifted positive and negative Gray code projection sequence; S320 , projecting the positive and negative Gray code projection sequences and the shifted positive and negative Gray code projection sequences in sequence from low to high according to the coding order, to complete the generation of the shifted positive and negative Gray code.

[0035] The method for generating the forward and reverse Gray code projection sequence and shifting the forward and reverse Gray code projection sequence comprises the following steps: S311, generating a traditional Gray code sequence, performing an inversion operation on each codeword in the traditional Gray code sequence to generate a corresponding inverse Gray code sequence; S312 , alternately combining the traditional Gray code sequence and the inverse Gray code sequence according to the codeword order to form a forward and reverse Gray code projection sequence.

[0036] S313, performing periodic shifting on the traditional Gray code sequence to generate a shifted Gray code sequence; S314, performing an inversion operation on each codeword in the shifted Gray code sequence to generate a corresponding shifted inverse Gray code sequence; S315 , alternately combining the shifted Gray code sequence and the shifted inverse Gray code sequence according to the codeword order to form a shifted forward and reverse Gray code projection sequence.

[0037] Steps S100-S300 above complete the event camera's focus and calculate its internal and external parameters. However, complete 3D measurement still requires further integration with structured light 3D measurement technology. To overcome the challenges posed by the binary and sparse imaging mode of event cameras, this embodiment proposes a shifted forward and reverse Gray code encoding method.

[0038] First, since the event camera is triggered by brightness changes and records binary event information, the binary encoding method of Gray code structured light is very suitable for three-dimensional measurement under event cameras. However, directly using the brightness changes generated by the projected Gray code pattern to generate the corresponding Gray code codeword information is very non-robust and is easily affected by noise events and ambient light, which causes Gray code recognition to fail, especially in the boundary area of ​​the Gray code. In order to improve the accuracy of Gray code boundary recognition under event cameras, the Gray code pattern is inverted to generate positive and negative Gray codes. By projecting positive and negative Gray code patterns, each area in the scene has a drastic intensity change of its corresponding code, which greatly improves the anti-interference ability. In addition, adjacent Gray code areas have opposite changes, resulting in clear and accurate Gray code boundaries, such as Figure 3 shown.

[0039] Secondly, due to the convolution effect of the point spread function of the optical system, when projecting high-order positive and negative Gray code patterns, some areas of the pattern will become blurred, and its intensity change will not exceed the threshold condition for event generation, thus causing Gray code codeword recognition to fail. Therefore, the present invention proposes a shifted positive and negative Gray code encoding method to avoid the impact of high-order Gray code pattern blur. This method shifts the low-order Gray code and combines the shifted Gray code with the original Gray code for encoding, such as Figure 4 shown.

[0040] The shifted forward and reverse Gray code encoded in step S320 is burned into the projection unit to facilitate the projection of the shifted forward and reverse Gray code.

[0041] In step S200 and step S300, the calibration target is placed in the measurement space, and its reflectivity is first imaged and substituted into the internal and external parameters of the event camera to obtain the target spatial position. Further, the projection shift is performed on it with positive and negative Gray codes, and the event camera detects the brightness changes in the scene and shoots back the event information corresponding to the Gray code pattern modulated three-dimensionally by the scene, and decodes the Gray codeword according to the event information, repeating multiple different depth positions. Finally, the three-dimensional measurement system calibration of the event camera structured light is completed according to the codeword information of each target and the internal and external parameters of the event camera to obtain the system calibration parameters. Among them, the system calibration method can be referred to Zhang Song (S. Zhang, "Novel method for structured light system calibration." Optical Engineering 45.8 (2006): 083601-083601). The system calibration results in this example are as follows Figure 5 shown.

[0042] In step S400, the positive and negative Gray code patterns are projected and shifted in the actual measurement scene, and the Gray code words are decoded according to the event information; by using the system calibration parameters, the three-dimensional surface shape of the object under measurement can be obtained through the Gray code word information.

[0043] In step S400, projecting the shifted positive and negative Gray code pattern in the actual measurement scene further includes the following steps: S410: The specific method of projecting and shifting the forward and reverse Gray codes in the actual measurement scene includes the following steps: After extracting the Gray code words of the shifted forward and reverse Gray code at different positions, the spatial position of each pixel is fitted with the Gray code word of the shifted forward and reverse Gray code to obtain a fitting coefficient; The spatial position of the object under measurement in the actual measurement scene is calculated based on the fitting coefficient and the Gray code word of the shifted forward and reverse Gray code.

[0044] The mapping relationship between the Gray code codewords of the shifted forward and reverse Gray code projected by the projection unit and the three-dimensional coordinates is actually the accurate three-dimensional coordinates in the event camera coordinate system obtained through event camera calibration. However, these three-dimensional coordinate acquisition methods are only applicable to special calibration targets (whose spatial structure is known, such as a checkerboard or a circular target). For unknown three-dimensional objects, it is impossible to determine them through event camera calibration alone. Therefore, structured light technology is introduced, and in this embodiment, Gray code technology is used. Due to the triangular geometric relationship between the projection unit and the event camera, for a pixel, when the object point it sees is at different positions in space, it receives different Gray code codewords projected by the projector, and theoretically, the relationship is linear.

[0045] Therefore, the forward and reverse Gray code is projected onto the calibration target by shifting the projections. After extracting the Gray code words at different positions, the spatial position (3D coordinate system) of each pixel is fitted to the Gray code word, obtaining fitting coefficients. The results are different for each pixel. In actual measurement, the spatial position (3D coordinate system) of the object to be measured can be calculated using the Gray code word and these coefficients.

[0046] In this example, a circular calibration target is used and 25 poses are placed for calibration. The camera calibration results are as follows: Figure 6 As shown, the standard parts measurement results are as follows Figure 7 As shown in the figure, the camera reprojection error is 0.05 pixels and the radius measurement error of the standard sphere is 0.08 mm. In addition, this example also conducts measurement experiments on the David statue and HDR scene. The measurement results are shown in the figure. Figure 7 As shown, Figure 7 (a) is a real picture of the David sculpture model. Figure 7 (b) is the reconstruction result of David’s model. Figure 7(c) is a real-world image of an HDR scene, which includes metal with high reflectivity and black objects with low reflectivity. Figure 7 (d) is the reconstruction result of the HDR scene. The experimental results show that the framework proposed in this paper can achieve high-precision event camera calibration and 3D reconstruction.

[0047] Some embodiments of the present application also provide a three-dimensional measurement system based on an event camera, including an event camera, a projection unit, and a data processing device.

[0048] The event camera is used to record event information according to brightness changes; the projection unit is used to project the shifted positive and negative Gray code and change the illumination of the scene; and the data processing device is used to decode the shifted positive and negative Gray code.

[0049] In this embodiment, the projection unit is preferably a projector, and the data processing device is preferably a computer.

[0050] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0051] Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in reverse order depending on the functions involved. For example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Furthermore, features described with reference to certain examples may be combined in other examples.

[0052] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A three-dimensional measurement method based on an event camera, characterized in that: The following steps are involved: Place the calibration target in the measurement space and obtain the target spatial position by combining the internal and external parameters of the event camera; Projecting a shifted forward and reverse Gray code onto the calibration target, and recording brightness changes with the event camera to obtain event information; Decoding the shifted forward and reverse Gray code according to event information obtained by recording brightness changes of the event camera, and obtaining system calibration parameters in combination with internal and external parameters of the event camera; The shifted forward and reverse Gray codes are projected on the actual measurement scene, the shifted forward and reverse Gray codes are decoded according to the event information recorded by the event camera in the actual measurement scene, and the three-dimensional surface shape of the object under measurement is obtained in combination with the system calibration parameters.

2. The three-dimensional measurement method based on an event camera according to claim 1, characterized in that: The acquisition of the internal and external parameters of the event camera includes the following steps: generating a reflectivity imaging pattern, and using the reflectivity imaging pattern to focus the event camera so that its clear imaging range covers the measurement space; The calibration target is placed at different positions in the measurement space, and the event camera images the calibration target at each position, and combines the reflectivity imaging pattern to obtain the internal and external parameters of the event camera.

3. The three-dimensional measurement method based on an event camera according to claim 2, characterized in that: The specific method of generating the reflectivity imaging pattern in the step includes the following steps: causing the illumination of the scene to change so that the event camera records event information of a plurality of pixels; The event information generated by each pixel within a set time is accumulated to generate the reflectivity imaging pattern.

4. The three-dimensional measurement method based on an event camera according to claim 3, characterized in that: The specific method of changing the lighting of the scene includes the following steps: A projection unit is used to change the lighting of the scene.

5. The three-dimensional measurement method based on an event camera according to claim 1, characterized in that: The method for generating the shifted forward and reverse Gray code comprises the following steps: Generate a forward and reverse Gray code projection sequence and a shifted forward and reverse Gray code projection sequence; The positive and negative Gray code projection sequences and the shifted positive and negative Gray code projection sequences are projected in sequence from low to high according to the coding order, so as to complete the generation of the shifted positive and negative Gray code.

6. The three-dimensional measurement method based on an event camera according to claim 5, characterized in that: The specific method for generating the forward and reverse Gray code projection sequence comprises the following steps: generating a traditional Gray code sequence, and performing an inversion operation on each codeword in the traditional Gray code sequence to generate a corresponding inverse Gray code sequence; The conventional Gray code sequence and the inverted Gray code sequence are alternately combined in a codeword order to form the forward and reverse Gray code projection sequence.

7. The three-dimensional measurement method based on an event camera according to claim 6, characterized in that: The specific method for generating the shifted positive and negative Gray code projection sequence comprises the following steps: Performing a periodic shift on the traditional Gray code sequence to generate a shifted Gray code sequence; Performing an inversion operation on each codeword in the shifted Gray code sequence to generate a corresponding shifted inverse Gray code sequence; The shifted Gray code sequence and the shifted inverse Gray code sequence are alternately combined in a codeword order to form the shifted forward and reverse Gray code projection sequence.

8. The three-dimensional measurement method based on an event camera according to claim 5, characterized in that: The specific method of projecting and shifting the positive and negative Gray codes on the calibration target comprises the following steps: The shifted forward and reverse Gray code is burned into a projection unit, and the projection unit is used to project the calibration target.

9. The three-dimensional measurement method based on an event camera according to claim 3, characterized in that: The specific method of projecting the shifted forward and reverse Gray code in the actual measurement scene includes the following steps: After extracting the Gray code words of the shifted forward and reverse Gray code at different positions, fitting the spatial position of each pixel with the Gray code word of the shifted forward and reverse Gray code to obtain a fitting coefficient; The spatial position of the object to be measured in the actual measurement scene is calculated based on the fitting coefficient and the Gray code word of the shifted forward and reverse Gray code.

10. A three-dimensional measurement system based on an event camera, applied to the three-dimensional measurement method based on an event camera according to any one of claims 1 to 9, characterized in that: include: Event camera, used to record event information based on brightness changes; A projection unit for projecting shifted positive and negative Gray codes and changing the scene illumination; Data processing equipment for decoding shifted forward and reverse Gray codes.

Images