Three-dimensional shape and surface temperature synchronous measurement method

Abstract

The invention belongs to the field of solid surface temperature shape measurement, and provides a three-dimensional shape and surface temperature synchronous measurement method. Comprising the steps of three-color mask three-dimensional imaging system setting, test environment building, spectral response coefficient calibration, three-color image acquisition, color channel separation, demosaicing hole interpolation, color crosstalk correction, optical flow estimation, three-dimensional coordinate acquisition, three-dimensional grid model generation, temperature evaluation and data fusion. According to the method, the multi-view information is simulated by using the single camera through the three-color mask, the equipment cost is reduced, the temperature is evaluated by using the brightness information of different color channels while multi-view three-dimensional reconstruction is performed on the same data through the multi-view information under the three-color mask, and the result of synchronously monitoring the temperature and the shape is achieved.

Description

Technical Field

[0001] The invention relates to the field of solid surface temperature and shape measurement, and in particular to a method for synchronously measuring a three-dimensional shape and surface temperature. Background Art

[0002] In the operation test of aircraft engines, accurate measurement of the three-dimensional shape deformation and temperature distribution of turbine blades is crucial for research and design; in technical processing, accurate control of the temperature of the metal surface can help control the heat treatment process such as quenching and annealing to help material processing and molding; in plastic processing, etc., the detection of the plastic surface and the subsequent appearance detection of the material blowing and the solid surface temperature detection can help reduce defects such as warping and shrinkage of the product and improve the precision and quality of the product. At the same time, it helps to improve the production efficiency of the product and save energy. For example, in the welding process, by real-time monitoring of the surface temperature of the welding part, the welding parameters such as current, voltage, welding speed, etc. can be adjusted to improve the welding efficiency and quality and reduce the occurrence of welding defects; in heating equipment such as kilns and ovens, accurate temperature control is ensured to avoid energy waste and reduce production costs. The operating status of the equipment can also be detected to ensure the safe operation of the equipment. In the design and manufacturing stage, the structure can also be designed more accurately by detecting temperature and deformation. The traditional multi-view stereo vision method uses multiple object images taken from different perspectives to obtain the three-dimensional information of the object by matching the feature points of the object in different images. This method is based on the principle of triangulation, that is, if the positions and postures of the two cameras and the positions of the feature points of the same object captured by them in the image are known, the position of the feature points in the three-dimensional space can be calculated. First, the three-view images are extracted, such as using algorithms such as cale-InvariantFeature Transform and SpeededUp RobustFeatures to extract features such as corner points and edge points in the image; then feature matching is performed to find the corresponding feature points in images of different viewpoints; finally, triangulation is performed based on the matched feature points and camera parameters to calculate the three-dimensional point cloud of the object. After obtaining the point cloud data, the quality of the point cloud can be further improved through point cloud processing algorithms such as filtering, denoising, and simplification, and then the point cloud can be converted into a continuous three-dimensional surface model through surface reconstruction algorithms such as Poisson reconstruction and Marching Cubes algorithm. The optical flow method uses the images of the object taken from multiple different viewpoints. The optical flow method can complete the three-dimensional reconstruction of each point of the object. Common optical flow algorithms include Horn-Schunck algorithm and Lucas-Kanade algorithm. The basic principle of these algorithms is to calculate the displacement vector of the pixel, that is, the optical flow, by analyzing the brightness change of the pixel in the image. Using a three-color mask as the three-view information, the optical flow method can be used to analyze each pixel more closely because the angle difference of the three-color mask is small. By analyzing the movement of the pixels in the image, the structure and motion information of the objects in the scene can be inferred, and then the three-dimensional structure of the scene can be restored. Colorimetric temperature measurement is a non-contact temperature measurement method. Its basic principle is based on the relationship between the radiation energy of an object at different wavelengths and its temperature.Any object will radiate energy when it is above absolute zero, and the distribution of its radiated energy follows Planck's law, Stefan-Boltzmann law, etc. According to Planck's law, the radiated energy of an object varies with wavelength and temperature. At a certain temperature, the distribution of the radiated energy of an object at different wavelengths is different. The colorimetric temperature measurement method usually uses two or more detectors with different wavelengths to receive the radiated energy of the object. Since the ratio of the radiated energy of an object at different wavelengths is different at different temperatures, the temperature of the object can be determined by measuring the ratio of the radiated energy at two or more specific wavelengths.

[0003] However, traditional methods require multiple cameras to collect multi-view images. In addition, existing methods are unable to monitor the shape of the model while achieving non-contact measurement. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a method for synchronously measuring a three-dimensional shape and surface temperature, so as to achieve synchronous measurement and fusion of a three-dimensional model and surface temperature.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for synchronously measuring a three-dimensional shape and a surface temperature, comprising:

[0007] A three-color mask three-dimensional imaging system is provided; the three-color mask three-dimensional imaging system comprises: a CCD camera and a three-color mask provided on the lens of the CCD camera; the three-color mask is a black light shielding sheet provided with red, green and blue light holes;

[0008] The ablation model to be tested is placed at the nozzle of the test section, and the three-color mask three-dimensional imaging system is set outside the observation window on the side of the test section;

[0009] When the three-color mask three-dimensional imaging system and the ablation model to be tested are at the same level, the three-color mask three-dimensional imaging system is used to obtain surface image data of the ablation model to be tested, and the spectral response coefficient of the three-color mask three-dimensional imaging system is calibrated according to the surface image data;

[0010] Acquiring a three-color image of the ablation model to be tested by using the three-color mask three-dimensional imaging system;

[0011] Separating the three-color image according to the color channels, and adjusting the brightness of the separated images to obtain a single-channel image with consistent brightness;

[0012] Performing de-mosaicing and hole interpolation on the single-channel image through an interpolation operation to obtain an interpolated image; the interpolation operation includes: dual three-color interpolation, bilinear interpolation, pattern recognition interpolation and deep learning interpolation;

[0013] Performing color crosstalk correction on the interpolated image to obtain a corrected image;

[0014] Using the optical flow method to estimate the motion between pixels in the corrected image under multiple viewing angles, and obtaining an optical flow field result;

[0015] According to the camera position of the three-color mask three-dimensional imaging system and the optical flow field result, the three-dimensional coordinates of the surface points of the ablation model to be measured are restored to obtain a three-dimensional point cloud;

[0016] The three-dimensional point cloud is converted into a three-dimensional mesh model by using a Poisson surface reconstruction method and a Delaunay triangulation method;

[0017] Performing temperature evaluation on the single-channel image using a colorimetric temperature measurement method and the spectral response coefficient to obtain temperature data;

[0018] The temperature data is fused with the three-dimensional model to obtain monitoring results of the three-dimensional shape and surface temperature.

[0019] Preferably, the calculation formula of the temperature data is:

[0020]

[0021] Among them, T s is the temperature data; r , g are the transmittance wavelength values ​​corresponding to red light and green light respectively; C2 is the radiation constant; R and G are both brightness information; K is the spectral response coefficient.

[0022] Preferably, the preset temperature is less than 3000K.

[0023] The present invention discloses the following technical effects:

[0024] The present invention provides a method for synchronously measuring three-dimensional shape and surface temperature. Multi-view information under a three-color mask is used to perform multi-view three-dimensional reconstruction, and brightness information of different color channels is used to evaluate the temperature. This solves the defect of high equipment cost of conventional methods and realizes synchronous measurement of temperature and object shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 creative labor.

[0026] Figure 1A schematic diagram of a three-dimensional shape and surface temperature simultaneous measurement process provided by an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of monitoring results provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The purpose of the present invention is to provide a method for synchronously measuring a three-dimensional shape and surface temperature, so as to realize synchronous measurement and fusion of a three-dimensional model and surface temperature.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Figure 1 A schematic diagram of a three-dimensional shape and surface temperature synchronous measurement process according to an embodiment of the present invention, Figure 2 A schematic diagram of monitoring results provided by an embodiment of the present invention, such as Figure 1 and Figure 2 As shown, the present invention provides a method for synchronously measuring a three-dimensional shape and a surface temperature, comprising:

[0032] Step 100: Setting a three-color mask three-dimensional imaging system; the three-color mask three-dimensional imaging system comprises: a CCD camera and a three-color mask arranged on the lens of the CCD camera; the three-color mask is a black light shielding sheet provided with red, green and blue light holes;

[0033] Step 200: placing the ablation model to be tested at the nozzle of the test section, and setting the three-color mask three-dimensional imaging system outside the side observation window of the test section;

[0034] Step 300: When the three-color mask 3D imaging system and the ablation model to be tested are at the same level, the three-color mask 3D imaging system is used to obtain surface image data of the ablation model to be tested, and the spectral response coefficient of the three-color mask 3D imaging system is calibrated according to the surface image data;

[0035] Step 400: using the three-color mask three-dimensional imaging system to obtain a three-color image of the ablation model to be tested;

[0036] Step 500: performing image separation on the three-color image according to the color channels, and adjusting the brightness of the separated images to obtain a single-channel image with consistent brightness;

[0037] Step 600: performing de-mosaic hole interpolation on the single-channel image through an interpolation operation to obtain an interpolated image; the interpolation operation includes: dual three-color interpolation, bilinear interpolation, pattern recognition interpolation and deep learning interpolation;

[0038] Step 700: performing color crosstalk correction on the interpolated image to obtain a corrected image;

[0039] Step 800: using an optical flow method to estimate the motion between pixels in the corrected image under multiple viewing angles, and obtaining an optical flow field result;

[0040] Step 900: according to the camera position of the three-color mask three-dimensional imaging system and the optical flow field result, the three-dimensional coordinates of the surface points of the ablation model to be measured are restored to obtain a three-dimensional point cloud;

[0041] Step 1000: converting the three-dimensional point cloud into a three-dimensional mesh model by using a Poisson surface reconstruction method and a Delaunay triangulation method;

[0042] Step 1100: using the colorimetric temperature measurement method and the spectral response coefficient to perform temperature evaluation on the single-channel image to obtain temperature data;

[0043] Step 1200: Fusing the temperature data with the three-dimensional model to obtain monitoring results of the three-dimensional shape and surface temperature.

[0044] Specifically, the calculation formula of the temperature data is:

[0045]

[0046] Among them, T s is the temperature data; r , g are the transmittance wavelength values ​​corresponding to red light and green light respectively; C2 is the radiation constant; R and G are both brightness information; K is the spectral response coefficient.

[0047] Preferably, the preset temperature is less than 3000K.

[0048] Specifically, the experiment simulated the operation condition of 7.8km / s, the ablation material used was a quartz fiber reinforced silica rocket model, the simulated working condition was 7.8km / s environment, and the speed state of low earth orbit was simulated. Low earth orbit (LEO) speed: about 7.8 kilometers per second. At this speed, the surface temperature of the rocket may be from several hundred degrees Celsius to more than one thousand degrees Celsius.

[0049] Preferably, the acquired three-color mask image is subjected to channel separation to obtain a red, green and blue three-color image. This process involves performing an image separation operation of three viewing angles on the color image based on the three color channels of red, green and blue.

[0050] Optionally, color crosstalk correction is performed on the three-view images to remove interference of colors of other channels on the current channel.

[0051] Furthermore, the pixel displacement obtained by optical flow estimation is used to match the same scene points. Based on the known camera position and the pixel position in the image, the 3D coordinates of the surface points of the object are restored. Then, 3D reconstruction is performed to generate a 3D point cloud using the 3D coordinates obtained from images of different viewpoints. Then, the point cloud is converted into a 3D mesh model using methods such as Poisson Surface Reconstruction and Delaunay Triangulation.

[0052] Specifically, the acquired three-color mask image is channel-separated to obtain a red, green, and blue three-color image, and the colorimetric temperature measurement method is used to evaluate the temperature. The intensity information of the red, green, and blue three-color images is combined with the calibrated spectral response coefficient K and is introduced into the following formula. In the formula, λ r , g The wavelength ranges of red light and green light are the corresponding transmittance wavelength values ​​of the filters, and the radiation constant C2 = 1.4388 × 10 -2 m·K. The calculation formula is as follows:

[0053]

[0054] The beneficial effects of the present invention are as follows:

[0055] The present invention uses a single camera to simulate multi-viewing angle information through a three-color mask, thereby reducing equipment costs. Through the multi-viewing angle information under the three-color mask, multi-viewing angle 3D reconstruction is performed on the same data, and the temperature is evaluated using the brightness information of different color channels, thereby achieving the result of synchronous monitoring of temperature and shape.

[0056] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0057] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for synchronously measuring three-dimensional shape and surface temperature, characterized in that: include: Setting up a three-color mask three-dimensional imaging system; The three-color mask three-dimensional imaging system comprises: a CCD camera and a three-color mask arranged on the lens of the CCD camera; the three-color mask is a black light shielding sheet provided with red, green and blue light holes; The ablation model to be tested is placed at the nozzle of the test section, and the three-color mask three-dimensional imaging system is set outside the observation window on the side of the test section; When the three-color mask three-dimensional imaging system and the ablation model to be tested are at the same level, the three-color mask three-dimensional imaging system is used to obtain surface image data of the ablation model to be tested, and the spectral response coefficient of the three-color mask three-dimensional imaging system is calibrated according to the surface image data; Acquiring a three-color image of the ablation model to be tested by using the three-color mask three-dimensional imaging system; Separating the three-color image according to the color channels, and adjusting the brightness of the separated images to obtain a single-channel image with consistent brightness; Performing de-mosaicing and hole interpolation on the single-channel image through an interpolation operation to obtain an interpolated image; the interpolation operation includes: dual three-color interpolation, bilinear interpolation, pattern recognition interpolation and deep learning interpolation; Performing color crosstalk correction on the interpolated image to obtain a corrected image; Using the optical flow method to estimate the motion between pixels in the corrected image under multiple viewing angles, and obtaining an optical flow field result; According to the camera position of the three-color mask three-dimensional imaging system and the optical flow field result, the three-dimensional coordinates of the surface points of the ablation model to be measured are restored to obtain a three-dimensional point cloud; The three-dimensional point cloud is converted into a three-dimensional mesh model by using a Poisson surface reconstruction method and a Delaunay triangulation method; Performing temperature evaluation on the single-channel image using a colorimetric temperature measurement method and the spectral response coefficient to obtain temperature data; The temperature data is fused with the three-dimensional grid model to obtain monitoring results of the three-dimensional shape and surface temperature.

2. A method for synchronously measuring three-dimensional shape and surface temperature according to claim 1, characterized in that: The calculation formula of the temperature data is: Among them, T s is the temperature data; r , g are the transmittance wavelength values ​​corresponding to red light and green light respectively; C2 is the radiation constant; R and G are both brightness information; K is the spectral response coefficient.

3. A method for synchronously measuring three-dimensional shape and surface temperature according to claim 1, characterized in that: The preset temperature is less than 3000K.

Images