CN110514392B - Temperature deformation measurement system and method based on wide-angle lens and image distortion correction - Google Patents
Temperature deformation measurement system and method based on wide-angle lens and image distortion correction Download PDFInfo
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- CN110514392B CN110514392B CN201910825008.4A CN201910825008A CN110514392B CN 110514392 B CN110514392 B CN 110514392B CN 201910825008 A CN201910825008 A CN 201910825008A CN 110514392 B CN110514392 B CN 110514392B
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- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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Abstract
The invention relates to a temperature deformation measurement system and method based on a wide-angle lens and image distortion correction, wherein the system comprises a closed experiment cabin provided with a high-temperature-resistant observation window, and a tested piece is fixed in the closed experiment cabin; the illumination light source is used for illuminating the surface of the tested piece; the wide-angle camera is used for acquiring an image of the surface of the tested piece; the heating device is used for heating the tested piece; the temperature measuring device is used for measuring the single-point temperature of the surface of the tested piece; and the control terminal is used for obtaining a deformation field of the surface of the tested piece according to the image of the surface of the tested piece after the distortion correction, and obtaining a temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after the distortion correction. The wide-angle camera can well enlarge the image acquisition range and acquire more effective experimental data; the distortion error of the image can be greatly reduced through distortion correction, and more accurate information of a deformation field and a temperature field is obtained.
Description
Technical Field
The disclosure relates to the technical field of material experiments, in particular to a temperature deformation measurement system and method based on a wide-angle lens and image distortion correction.
Background
In the field of aerospace, the complex service environment of a high-temperature and high-speed flow field brings great challenges to aerospace thermal protection. Before service, the performance of a thermal protection system such as materials/structures and the like is generally tested and evaluated in a ground examination mode, and images acquired by a camera in the conventional high-temperature wind tunnel of the conventional high-temperature wind tunnel are limited by an observation window and an observation position, so that the acquired region is very limited, and the experimental data amount is small.
Disclosure of Invention
In view of the above, the present disclosure provides a system and a method for measuring temperature deformation in a wide-angle lens and correcting image distortion, so as to solve the problem that an image area obtained by a high-temperature wind tunnel observation means is limited.
According to an aspect of the present disclosure, there is provided a temperature deformation measurement system based on a wide-angle lens and image distortion correction, including:
the test device comprises a closed experiment cabin provided with a high-temperature-resistant observation window, wherein a tested piece is fixed in the closed experiment cabin;
the lighting source is arranged outside the closed experimental cabin and is used for irradiating the surface of the tested piece;
the wide-angle camera is arranged outside the closed experimental cabin and is used for acquiring an image of the surface of the tested piece;
the heating device is arranged in the closed experiment cabin and used for heating the tested piece;
the temperature measuring device is arranged outside the closed experimental cabin and is used for measuring the single-point temperature of the surface of the tested piece;
and the control terminal is used for obtaining a deformation field of the surface of the tested piece according to the image of the surface of the tested piece after distortion correction, and obtaining a temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction.
In one possible implementation manner, the control terminal is further configured to: calibrating the wide-angle camera through a calibration template to obtain conversion parameters between a distorted image and a real image acquired by the wide-angle camera, and determining a distortion correction model according to the conversion parameters;
the distortion correction model includes: a geometric coordinate position distortion correction sub-model and a gray value distortion correction sub-model.
In one possible implementation manner, the control terminal is further configured to:
denoising the image of the surface of the tested piece through median filtering;
and correcting the image subjected to the denoising treatment according to the distortion correction model to obtain an image of the surface of the tested piece subjected to the distortion correction.
In a possible implementation manner, the calibrating the wide-angle camera by using the calibration template to obtain a conversion parameter between a distorted image and a real image acquired by the wide-angle camera, and determining a distortion correction model according to the conversion parameter includes:
extracting a first characteristic point coordinate from a real image of a calibration template, and extracting a second characteristic point coordinate corresponding to the first characteristic point coordinate from a distorted image collected by a wide-angle camera;
and obtaining a conversion parameter between a distorted image coordinate and a real image coordinate by polynomial fitting according to the first characteristic point coordinate and the second characteristic point coordinate, and obtaining the geometric coordinate position distortion correction submodel according to the conversion parameter.
In a possible implementation manner, the calibrating the wide-angle camera by using the calibration template to obtain a conversion parameter between a distorted image and a real image acquired by the wide-angle camera, and determining a distortion correction model according to the conversion parameter further includes:
and obtaining the gray value distortion correction sub-model by utilizing bilinear interpolation according to the gray values of four pixel points adjacent to the target pixel point in the distorted image collected by the wide-angle camera in the real image of the calibration template.
In one possible implementation manner, the control terminal is further configured to:
controlling the illumination light source to provide illumination to the surface of the tested piece through the high-temperature-resistant observation window;
controlling the wide-angle camera to acquire an image of the surface of the tested piece through the high-temperature-resistant observation window;
controlling the heating device to heat the tested piece;
and controlling the temperature measuring device to measure the single-point temperature of the surface of the tested piece through the high-temperature-resistant observation window.
In one possible implementation, the wide-angle camera is a charge coupled device camera integrated with a wide-angle lens, and the wide-angle lens is additionally provided with a blue filter.
According to another aspect of the present disclosure, there is provided a temperature deformation measurement method based on a wide-angle lens and image distortion correction, including:
irradiating the surface of a tested piece in the closed experiment cabin by an illumination light source;
acquiring an image of the surface of the tested piece through a wide-angle camera;
heating the tested piece by a heating device;
measuring the single-point temperature of the surface of the tested piece by a temperature measuring device;
obtaining a deformation field of the surface of the tested piece according to the image of the surface of the tested piece after distortion correction; and obtaining the temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction.
According to another aspect of the present disclosure, there is provided a temperature deformation measuring apparatus based on a wide-angle lens and image distortion correction, including:
the illumination module is used for illuminating the surface of the tested piece in the closed experiment cabin through the illumination light source;
the image acquisition module is used for acquiring an image of the surface of the tested piece through a wide-angle camera;
the heating module is used for heating the tested piece through a heating device;
the single-point temperature measuring module is used for measuring the single-point temperature of the surface of the tested piece through the temperature measuring device;
the control module is used for obtaining a deformation field of the surface of the tested piece according to the image of the surface of the tested piece after distortion correction; and obtaining the temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction.
According to another aspect of the present disclosure, there is provided a non-transitory computer readable storage medium having computer program instructions stored thereon, wherein the computer program instructions, when executed by a processor, implement the above-described method.
According to the method, the wide-angle camera arranged outside the closed experimental cabin is used for acquiring the image of the surface of the tested piece, so that the image acquisition range can be well expanded, and more effective experimental data can be acquired; and according to the image of the surface of the tested piece after distortion correction, a deformation field of the surface of the tested piece is obtained, and according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction, a temperature field of the surface of the tested piece is obtained, so that the interference of image distortion brought by a wide-angle lens on data processing and analysis can be effectively eliminated, distortion errors are greatly reduced, and more accurate information of the deformation field and the temperature field is obtained.
Other features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments, features, and aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.
FIG. 1 illustrates a block diagram of a wide-angle lens and image distortion correction based temperature distortion measurement system according to an embodiment of the present disclosure;
FIG. 2 illustrates a control terminal workflow diagram for temperature distortion measurement based on wide angle lens and image distortion correction according to an embodiment of the present disclosure;
FIG. 3 illustrates a schematic diagram of an image acquisition principle of a wide-angle camera according to an embodiment of the present disclosure;
FIG. 4 is a schematic diagram illustrating a principle of gray scale image correction linear difference according to an embodiment of the present disclosure;
FIG. 5 shows a block diagram of a control terminal for temperature distortion measurement based on a wide-angle lens and image distortion correction, according to an embodiment of the present disclosure;
FIG. 6 illustrates a flow chart of a method for temperature distortion measurement based on a wide-angle lens and image distortion correction, according to an embodiment of the present disclosure;
FIG. 7 illustrates a flow chart of a method for temperature distortion measurement based on a wide-angle lens and image distortion correction, according to an embodiment of the present disclosure;
fig. 8 illustrates a block diagram of a temperature distortion measurement device based on a wide-angle lens and image distortion correction according to an embodiment of the present disclosure.
Detailed Description
Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present disclosure. It will be understood by those skilled in the art that the present disclosure may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present disclosure.
In the field of aerospace, the complex service environment of a high-temperature and high-speed flow field brings great challenges to aerospace thermal protection. When the aircraft is cruising at a high speed and is re-entering, all the components of the engine, the nose cone, the leading edge and other key structural components are tested in extreme environments such as ultra-high speed, ultra-high temperature and the like. The extreme environment is accompanied with the challenges of a plurality of problems such as thermochemical ablation, pneumatic thermal environment, boundary layer transition, pneumatic appearance evolution and the like. The stable thermal protection system is necessary guarantee for normal operation of internal instrument equipment, so that the reliability and safety verification of the thermal protection system have a key significance for the safe service of the high-speed aircraft. In order to verify the reliability and safety of the thermal protection system, the performance of the thermal protection system such as material/structure and the like is generally required to be tested and evaluated in a ground examination mode before service, and the high-temperature wind tunnel is used as an important form of ground examination and is increasingly widely applied in the field of aerospace.
The existing high-temperature wind tunnel observation means is mainly a digital image correlation method based on binocular vision, and a conventional binocular CCD camera is used for image acquisition, but in the actual experiment process, the size and the position of an observation window of the existing high-temperature wind tunnel experiment equipment are limited, so that the image area which can be acquired when the method is used for image acquisition is very limited.
Therefore, the system uses the wide-angle lens to collect wind tunnel examination test images, integrates an image deformity correction processing method at a computer and other control terminals, and is used for processing and analyzing image data so as to obtain more accurate and effective experimental data.
Fig. 1 illustrates a block diagram of a temperature distortion measurement system based on a wide-angle lens and image distortion correction according to an embodiment of the present disclosure. As shown in fig. 1, the system includes: the test device comprises a closed experiment cabin 1 provided with a high-temperature-resistant observation window 5, wherein a tested piece 4 is fixed in the closed experiment cabin 1; the illumination light source 8 is arranged outside the closed experiment cabin 1 and is used for illuminating the surface of the tested piece 4; the wide-angle camera 6 is arranged outside the closed experiment chamber 1 and is used for acquiring an image of the surface of the tested piece 4; the heating device 2 is arranged in the closed experiment cabin 1 and is used for heating the tested piece 4; the temperature measuring device 7 is arranged outside the closed experiment cabin 1 and is used for measuring the single-point temperature of the surface of the tested piece 4; and the control terminal 9 is used for obtaining a deformation field (including a displacement field and a strain field) of the surface of the tested piece according to the image of the surface of the tested piece after the distortion correction, and obtaining a temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after the distortion correction.
The tested piece in the disclosure can be a test piece made of carbon/silicon carbide composite material widely applied to aviation and aerospace thermal protection, or any other test piece needing high-temperature wind tunnel examination and test. The size of the test piece may be selected according to the specification of the test object and the closed experimental chamber, but is not limited thereto, and in an exemplary embodiment, the size of the test piece may be 50mm × 50mm × 10 mm. The illumination light source provides illumination for the experimental environment and the surface of the tested piece, and can be a narrow-band monochromatic LED light source (such as a narrow-band blue light source). The temperature measuring device may be: the temperature of a single point on the surface of the tested piece can represent the temperature of any point on the surface of the tested piece, and the temperature change of the single point is recorded in real time in the experimental process. The tested piece can be fixed at a proper position in the closed experiment chamber through the clamping device 3 to carry out high-temperature environment test. The heating device is fixed at a specified position in the closed experiment chamber and is aligned to the surface of the tested piece to be heated in the experiment process. The heating device can be an oxyacetylene flame spray gun, oxyacetylene flame is adopted for heating, the inner diameter of a flame nozzle is 2mm, the distance between the spray gun and the surface of a tested piece can be 4-5 cm, the air pressures of oxygen and acetylene in the heating device can be 0.4MPa and 0.095MPa respectively, the flow rates are 4.14L/min and 2.46L/min respectively, and 1100 ℃ local heating of the surface of a measured test piece can be realized.
It should be noted that, a high temperature resistant observation window is provided on the closed experiment chamber, and is used as a channel for measuring the single-point temperature of the surface of the tested piece by a temperature measuring device in the experiment process, acquiring the real-time image of the tested piece by a wide-angle camera and irradiating the surface of the tested piece by an illumination light source, the provided position and size need to meet the safety standard, and in order to ensure the safety of the extravehicular experimenter in the experiment process, the high temperature resistant observation window is generally provided with a small size, meanwhile, because the arrangement position of a heating device in the closed experiment chamber needs to meet a certain standard and is limited by the environmental space in the closed experiment chamber, the tested piece needs to be close to the heating device, so that the image of the surface of the tested piece acquired by a conventional camera can have incomplete phenomenon through the high temperature resistant observation window, the acquired experiment data amount is small; therefore, the wide-angle camera is adopted to collect images in real time, the image collecting range can be well enlarged, image observation with a larger visual angle is realized in a limited observation window, more effective experimental data are obtained, and the reliability and the accuracy of experimental results are improved.
In a possible implementation manner, the wide-angle camera in the disclosure may be a Charge Coupled Device (CCD) camera integrated with a wide-angle lens, and is configured to acquire a real-time image of a wind tunnel examination, where the wide-angle lens is additionally provided with a narrow-band filter, so that interference of radiation light on the surface of a test piece and other light sources (such as natural light) can be reduced.
In one possible implementation manner, the control terminal may be connected to the illumination light source, the heating device, the temperature measuring device, and the wide-angle camera, respectively; the control terminal may be further configured to: controlling the illumination light source to provide illumination to the surface of the tested piece through the high-temperature-resistant observation window; controlling the wide-angle camera to acquire an image of the surface of the tested piece through the high-temperature-resistant observation window; controlling the heating device to heat the tested piece; and controlling the temperature measuring device to measure the single-point temperature of the surface of the tested piece through the high-temperature-resistant observation window.
FIG. 2 illustrates a control terminal workflow diagram for temperature distortion measurement based on wide angle lens and image distortion correction according to an embodiment of the present disclosure; as shown in fig. 2, the control terminal is used for storing and processing image information and temperature information in real time and correcting a measured image through distortion correction; determining a deformation field (including a displacement field and a strain field) of the surface of the tested piece according to the image acquired when the light source emits light after distortion correction, and determining a temperature field of the surface of the tested piece according to the image acquired when the light source emits light after distortion correction and the single-point temperature of the determination point.
The image on the surface of the tested piece is collected through the wide-angle camera in the method, the image can be distorted, and the image distortion caused by the wide-angle lens can bring great errors for further data processing and analysis, so that the distorted image collected by the wide-angle lens needs to be subjected to distortion correction, the distortion error is reduced, and the accuracy of an experimental result is improved.
FIG. 3 illustrates a schematic diagram of an image acquisition principle of a wide-angle camera according to an embodiment of the present disclosure; as shown in fig. 3, the distortion generated by the wide-angle lens is mainly composed of radial distortion, eccentric distortion and thin prism distortion, and the relationship between the image coordinate point (x, y) and the ideal coordinate point (u, v) after actual distortion can be described as
Wherein the content of the first and second substances,xandyrepresenting the amount of shift of the actual distorted image coordinates in the x and y directions respectively,xandycan be composed ofThe expression of the joint action of three kinds of distortion is expressed:
wherein k is1And k2Distortion coefficient, p, representing radial distortion1And p2Distortion coefficient, s, representing eccentric distortion1And s2A distortion factor representing distortion of a thin prism.
In general, the distortion generated by the wide-angle lens is mainly radial distortion, and therefore the above expression (1) is simplified to
Wherein
Representing the radius from the current distortion correction point to the center point of the distorted image; in correcting an image containing distortion, the following expression can be used to describe:
f(x,y)＝T(f(u,v))…………………………(2)
wherein f (x, y) is a distorted image collected by a wide-angle camera, (x, y) is a coordinate point of the distorted image, (u, v) represents an ideal image, (u, v) is a coordinate point in the ideal image, and T represents an established image distortion correction model;
in one possible implementation, the control terminal is further configured to: calibrating the wide-angle camera through a calibration template to obtain conversion parameters between a distorted image and a real image acquired by the wide-angle camera, and determining a distortion correction model according to the conversion parameters; correcting the acquired distorted image by using the distortion correction model;
the correction of the distorted image mainly comprises two aspects: the correction of geometric coordinate position and the correction of gray value distortion, so the established distortion correction model mainly comprises two parts: a geometric coordinate position distortion correction sub-model and a gray value distortion correction sub-model.
In a possible implementation, the determining the distortion correction model may include: extracting a first characteristic point coordinate from a real image of a calibration template, and extracting a second characteristic point coordinate corresponding to the first characteristic point coordinate from a distorted image collected by a wide-angle camera; and obtaining a conversion parameter between a distorted image coordinate and a real image coordinate by polynomial fitting according to the first characteristic point coordinate and the second characteristic point coordinate, and obtaining the geometric coordinate position distortion correction submodel according to the conversion parameter.
For example, two sets of corresponding feature points (i.e., a first feature point and a second feature point) are extracted from an original image and a distorted image in a calibration plate, a mapping relation is established according to corresponding feature point coordinates, unknown parameters are solved, and a calibration process is completed through the function mapping relation. In the process, a polynomial fitting method can be adopted for fitting, and the relationship between the coordinate points of the distorted image and the ideal image (the original image in the calibration plate) is described, and an expression can be expressed as follows:
wherein, aijAnd bijAll the coefficients are undetermined coefficients, n is the used polynomial degree, the value of n can be 4 or 5, x and y are coordinates of the midpoint of the distorted image, and u and v are coordinates of the midpoint of the ideal image.
In the present disclosure for solving the above undetermined coefficient aijAnd bijWhen fitting, the least square method is used for improving the precision so that the error of the fitting is minimum (the square sum of the fitting errors is minimum); after the least square method is used for solving to obtain the fitting coefficient, the conversion parameter between the distorted image coordinate and the real image coordinate can be determined, and the geometric coordinate position distortion correction submodel is obtained.
In a possible implementation manner, the determining the distortion correction model may further include: and obtaining the gray value distortion correction sub-model by utilizing bilinear interpolation according to the gray values of four pixel points adjacent to the target pixel point in the distorted image collected by the wide-angle camera in the real image of the calibration template.
For example, the method adopts bilinear interpolation to improve the accuracy of the constructed gray scale syndrome model, firstly obtains the known gray scale values of the four adjacent point pixels of the target pixel, and simultaneously performs linear interpolation in two mutually perpendicular directions. As shown in fig. 4, if the coordinates of the target pixel (i.e. the pixel in the distorted image) are (x, y), the gray value f (p) is unknown; the coordinates of four adjacent points near the pixel point are respectively A (x)1,y1),B(x2,y1),C(x1,y2),D(x2,y2) The gray values corresponding to the adjacent points are respectively f (A), f (B), f (C) and f (D), and linear interpolation is respectively carried out in the x direction and the y direction to obtain:
performing deformation processing on the formula (4), and obtaining a result of the bilinear interpolation as follows:
the above equation (5) is a gray value distortion correction submodel.
After the distortion correction model is obtained, correcting an image (source image) which is acquired by a wide-angle camera and has distortion on the surface of the tested piece, namely correcting the distortion of the geometric coordinate position and the distortion of the gray value through the calibrated basic parameters and the calibrated basic model (namely the distortion correction model obtained by calibration) to obtain a more accurate adjustment image (namely the image after distortion correction); in the correction process, the conversion of the image space coordinates (namely, the distortion correction of the position of the geometric coordinates) is firstly carried out, and after the position coordinates of the pixel points of the image are geometrically corrected, the gray information of the corresponding pixel points is determined (namely, the gray image correction).
In a possible implementation manner, as shown in fig. 2, the control terminal is further configured to: denoising the image of the surface of the tested piece through median filtering; and correcting the image subjected to the denoising treatment according to the distortion correction model to obtain an image of the surface of the tested piece subjected to the distortion correction. The source image is subjected to denoising processing (such as median filtering and wiener filtering) through filtering, and the definition of the image is improved.
The deformed image acquired by the wide-angle camera can be converted into an actual observation image (image after distortion correction) after the image deformation correction, as shown in fig. 2, the actual deformation field (including a displacement field and a strain field) information of the surface of the tested piece is determined through the image after the distortion correction at two different moments (two adjacent frames of images, for example, the frequency of the acquired image can be 5 frames per second), and the actual temperature field information of the surface of the tested piece is acquired by a colorimetric method according to single-point temperature measuring point data; wherein, the calculation of the deformation field (including the strain field and the displacement field) is obtained by the digital image correlation method; "colorimetry" can be expressed as using the known temperature of a point on the surface of an object and the ratio of the intensity of two adjacent narrow-band light radiations emitted from the point and other points on the surface of the object to obtain the temperature field of the surface of the object.
For example, the temperature of the point of the moderate brightness region on the surface of the test object can be used as the single-point temperature, and the temperature field on the surface of the test object can be obtained by colorimetry according to the temperature of the point of the moderate brightness region on the surface of the test object and the image after the distortion correction of the surface of the test object. The point of the moderate-brightness area can be represented as a point which is not excessively dark or excessively exposed in an image of the surface of the tested piece (for example, a point of the photographed surface of the tested piece with a pixel gray-scale value of 100-180 can be used as the point of the moderate-brightness area), so that the obtained temperature field can more accurately reflect the temperature of each point of the surface of the tested piece.
In a possible implementation manner, fig. 5 shows a block diagram of a control terminal for temperature deformation measurement based on a wide-angle lens and image distortion correction according to an embodiment of the present disclosure, and as shown in fig. 5, the control terminal 9 may include: the processing component 922, which further includes one or more processors, and memory resources, represented by memory 932, for storing instructions, such as applications, that are executable by the processing component 922. The application programs stored in memory 932 may include one or more modules that each correspond to a set of instructions. Further, the processing component 922 is configured to execute instructions to perform the functions of the control terminal 9 described above.
The control terminal 9 may also include a power supply component 926 configured to control power management of the terminal 9, a wired or wireless network interface 950 configured to connect the control terminal 9 to a network, and an input output (I/O) interface 958. The control terminal 9 may operate based on an operating system stored in memory 932, such as Windows Server, Mac OS XTM, UnixTM, LinuxTM, FreeBSDTM, or the like.
Therefore, the wide-angle camera arranged outside the closed experimental cabin acquires the image of the surface of the tested piece, can well expand the image acquisition range and acquire more effective experimental data; and according to the image of the surface of the tested piece after distortion correction, a deformation field (including a displacement field and a strain field) of the surface of the tested piece is obtained, and according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction, a temperature field of the surface of the tested piece is obtained, so that the interference brought to data processing and analysis by image distortion brought by a wide-angle lens can be effectively eliminated, the distortion error is greatly reduced, and more accurate information of the deformation field and the temperature field is obtained.
Fig. 6 shows a flowchart of a temperature distortion measurement method based on a wide-angle lens and image distortion correction according to an embodiment of the present disclosure. As shown in fig. 6, the method may include the steps of:
step S10, irradiating the surface of the tested piece in the closed experiment cabin through an illumination light source;
step S20, acquiring an image of the surface of the tested piece through a wide-angle camera;
step S30, heating the tested piece through a heating device;
step S40, measuring the single-point temperature of the surface of the tested piece through a temperature measuring device;
step S50, obtaining a deformation field (including a displacement field and a strain field) of the surface of the tested piece according to the image of the surface of the tested piece after distortion correction; and obtaining the temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction.
In a possible implementation manner, in step S50, the method may include step S51, calibrating the wide-angle camera through a calibration template, obtaining a conversion parameter between a distorted image and a real image acquired by the wide-angle camera, and determining a distortion correction model according to the conversion parameter; wherein the distortion correction model may include: a geometric coordinate position distortion correction sub-model and a gray value distortion correction sub-model.
In a possible implementation manner, in step S50, a step S52 may further be included, where the image of the surface of the test piece is subjected to denoising processing through median filtering; and correcting the image subjected to the denoising treatment according to the distortion correction model to obtain an image of the surface of the tested piece subjected to the distortion correction.
In one possible implementation manner, in step S51, the following steps may be included:
step S511, extracting a first characteristic point coordinate from a real image of the calibration template, and extracting a second characteristic point coordinate corresponding to the first characteristic point coordinate from a distorted image collected by the wide-angle camera;
and S512, obtaining a conversion parameter between a distorted image coordinate and a real image coordinate by polynomial fitting according to the first characteristic point coordinate and the second characteristic point coordinate, and obtaining the geometric coordinate position distortion correction submodel according to the conversion parameter.
In one possible implementation manner, in step S51, the following steps may be further included:
and step S513, obtaining the gray value distortion correction sub-model by utilizing bilinear interpolation according to the gray values of four pixel points adjacent to the target pixel point in the distortion image collected by the wide-angle camera in the real image of the calibration template.
In one possible implementation, the wide-angle camera is a charge coupled device camera integrated with a wide-angle lens, and the wide-angle lens is additionally provided with a blue filter.
For example, fig. 7 shows a flowchart of a temperature deformation measurement method based on a wide-angle lens and image distortion correction according to an embodiment of the present disclosure, and as shown in fig. 7, the method may include: erecting an image acquisition device (wide-angle camera), a temperature measuring device and an illumination light source at a high-temperature resistant observation window, adjusting the measuring device to a proper position, and placing a tested piece on a clamping device to finish the fixation of the test piece; turning on an illumination light source, calibrating a wide-angle CCD camera, obtaining conversion parameters of a collected image (distorted image) and a real image (calibration plate image), determining a distortion correction model, and marking a temperature measuring point of a single-point temperature measuring device; keeping the light source on, starting the heating device, synchronously starting the temperature measuring device and the wide-angle camera, testing the tested piece, recording single-point temperature data and real-time image information, and storing the image data as a source image (namely an image of the surface of the tested piece); after the experiment is finished, the heating device is closed, the illumination light source, the temperature measuring device and the wide-angle camera are closed, meanwhile, filtering processing and distortion correction are carried out on the source image, for example, the source image can be subjected to denoising processing through median filtering, and then geometric coordinate position distortion and gray value distortion are corrected sequentially through basic parameters and basic models (distortion correction models) obtained through calibration, so that an 'adjustment image' (namely an image of the surface of the tested piece after distortion correction) is obtained; calculating surface deformation fields (including displacement fields and strain fields) according to the surface images of the 'adjustment images' at different moments; according to the single-point temperature measurement data in the 'adjustment image', the temperature field of the surface of the tested piece is calculated by a colorimetric method.
Fig. 8 illustrates a block diagram of a temperature distortion measurement device based on a wide-angle lens and image distortion correction according to an embodiment of the present disclosure. As shown in fig. 8, the apparatus may include: the illumination module 41 is used for illuminating the surface of the tested piece in the closed experiment cabin through the illumination light source; an image acquisition module 42, configured to acquire an image of the surface of the test piece through a wide-angle camera; a heating module 43 for heating the test piece by a heating device; a single-point temperature measuring module 44 for measuring a single-point temperature of the surface of the test piece by a temperature measuring device; the control module 45 is used for obtaining a deformation field of the surface of the tested piece according to the image of the surface of the tested piece after distortion correction; and obtaining the temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction.
In one possible implementation, the control module 45 may include: the calibration submodule is used for calibrating the wide-angle camera through a calibration template to obtain conversion parameters between a distorted image and a real image acquired by the wide-angle camera, and determining a distortion correction model according to the conversion parameters; the distortion correction model may include: a geometric coordinate position distortion correction sub-model and a gray value distortion correction sub-model.
In one possible implementation, the control module 45 may further include: the distortion correction submodule is used for carrying out denoising processing on the image of the surface of the tested piece through median filtering; and correcting the image subjected to the denoising treatment according to the distortion correction model to obtain an image of the surface of the tested piece subjected to the distortion correction.
In one possible implementation, the calibration sub-module may include: the geometric coordinate position distortion corrector model unit is used for extracting a first characteristic point coordinate from a real image of the calibration template and extracting a second characteristic point coordinate corresponding to the first characteristic point coordinate from a distorted image acquired by the wide-angle camera; and obtaining a conversion parameter between a distorted image coordinate and a real image coordinate by polynomial fitting according to the first characteristic point coordinate and the second characteristic point coordinate, and obtaining the geometric coordinate position distortion correction submodel according to the conversion parameter.
In a possible implementation manner, the calibration sub-module may further include: and the gray value distortion correction sub-model unit is used for obtaining the gray value distortion correction sub-model by utilizing bilinear interpolation according to the gray values of four pixel points adjacent to the target pixel point in the distorted image collected by the wide-angle camera in the real image of the calibration template.
In one possible implementation, the wide-angle camera is a charge coupled device camera integrated with a wide-angle lens, and the wide-angle lens is additionally provided with a blue filter.
In an exemplary embodiment, a non-transitory computer readable storage medium, such as the memory 932, is also provided that includes computer program instructions executable by the processing component 922 of the control terminal 9 to perform the above-described methods.
The present disclosure may be systems, methods, and/or computer program products. The computer program product may include a computer-readable storage medium having computer-readable program instructions embodied thereon for causing a processor to implement various aspects of the present disclosure.
The computer readable storage medium may be a tangible device that can hold and store the instructions for use by the instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic memory device, a magnetic memory device, an optical memory device, an electromagnetic memory device, a semiconductor memory device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a Static Random Access Memory (SRAM), a portable compact disc read-only memory (CD-ROM), a Digital Versatile Disc (DVD), a memory stick, a floppy disk, a mechanical coding device, such as punch cards or in-groove projection structures having instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media as used herein is not to be construed as transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission medium (e.g., optical pulses through a fiber optic cable), or electrical signals transmitted through electrical wires.
The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to a respective computing/processing device, or to an external computer or external storage device via a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. The network adapter card or network interface in each computing/processing device receives computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in the respective computing/processing device.
The computer program instructions for carrying out operations of the present disclosure may be assembler instructions, Instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, the electronic circuitry that can execute the computer-readable program instructions implements aspects of the present disclosure by utilizing the state information of the computer-readable program instructions to personalize the electronic circuitry, such as a programmable logic circuit, a Field Programmable Gate Array (FPGA), or a Programmable Logic Array (PLA).
Various aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.
These computer-readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer-readable program instructions may also be stored in a computer-readable storage medium that can direct a computer, programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer-readable medium storing the instructions comprises an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.
The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer, other programmable apparatus or other devices implement the functions/acts specified in the flowchart and/or block diagram block or blocks.
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (8)
1. The utility model provides a temperature deformation measurement system based on wide-angle lens and image distortion are rectified, its characterized in that, the system is applied to high temperature wind tunnel test, includes:
the test device comprises a closed experiment cabin provided with a high-temperature-resistant observation window, wherein a tested piece is fixed in the closed experiment cabin; the tested piece is a test piece made of carbon/silicon carbide composite material applied to aerospace thermal protection;
the lighting source is arranged outside the closed experimental cabin and is used for irradiating the surface of the tested piece;
the wide-angle camera is arranged outside the closed experimental cabin and used for acquiring an image of the surface of the tested piece through the high-temperature-resistant observation window; the wide-angle camera is a charge coupled device camera integrated with a wide-angle lens, and a blue filter is additionally arranged on the wide-angle lens;
the heating device is arranged in the closed experiment cabin and used for heating the tested piece;
the temperature measuring device is arranged outside the closed experimental cabin and is used for measuring the single-point temperature of the surface of the tested piece;
the control terminal is used for carrying out distortion correction on the image of the surface of the tested piece through a distortion correction model, obtaining a deformation field of the surface of the tested piece according to the image of the surface of the tested piece after distortion correction, and obtaining a temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction;
the distortion correction model includes: a geometric coordinate position distortion correction sub-model; the control terminal is further configured to: extracting a first characteristic point coordinate from a real image of a calibration template, and extracting a second characteristic point coordinate corresponding to the first characteristic point coordinate from a distorted image collected by a wide-angle camera; and obtaining a conversion parameter between a distorted image coordinate and a real image coordinate by polynomial fitting according to the first characteristic point coordinate and the second characteristic point coordinate, and obtaining the geometric coordinate position distortion correction submodel according to the conversion parameter.
2. The system of claim 1, wherein the distortion correction model further comprises a gray value distortion correction submodel.
3. The system of claim 2, wherein the control terminal is further configured to:
denoising the image of the surface of the tested piece through median filtering;
and correcting the image subjected to the denoising treatment according to the distortion correction model to obtain an image of the surface of the tested piece subjected to the distortion correction.
4. The system of claim 2, wherein the control terminal is further configured to:
and obtaining the gray value distortion correction sub-model by utilizing bilinear interpolation according to the gray values of four pixel points adjacent to the target pixel point in the distorted image collected by the wide-angle camera in the real image of the calibration template.
5. The system of claim 1, wherein the control terminal is further configured to:
controlling the illumination light source to provide illumination to the surface of the tested piece through the high-temperature-resistant observation window;
controlling the wide-angle camera to acquire an image of the surface of the tested piece through the high-temperature-resistant observation window;
controlling the heating device to heat the tested piece;
and controlling the temperature measuring device to measure the single-point temperature of the surface of the tested piece through the high-temperature-resistant observation window.
6. A temperature deformation measurement method based on wide-angle lens and image distortion correction is characterized in that the method is applied to high-temperature wind tunnel test and comprises the following steps:
irradiating the surface of a tested piece in the closed experiment cabin by an illumination light source; the tested piece is a test piece made of carbon/silicon carbide composite material applied to aerospace thermal protection;
acquiring an image of the surface of the tested piece through a wide-angle camera and a high-temperature-resistant observation window arranged on the closed experiment cabin; the wide-angle camera is a charge coupled device camera integrated with a wide-angle lens, and a blue filter is additionally arranged on the wide-angle lens;
heating the tested piece by a heating device;
measuring the single-point temperature of the surface of the tested piece by a temperature measuring device;
carrying out distortion correction on the image of the surface of the tested piece through a distortion correction model, and obtaining a deformation field of the surface of the tested piece according to the image of the surface of the tested piece after the distortion correction; obtaining a temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction;
the distortion correction model includes: a geometric coordinate position distortion correction sub-model; the method further comprises the following steps: extracting a first characteristic point coordinate from a real image of a calibration template, and extracting a second characteristic point coordinate corresponding to the first characteristic point coordinate from a distorted image collected by a wide-angle camera; and obtaining a conversion parameter between a distorted image coordinate and a real image coordinate by polynomial fitting according to the first characteristic point coordinate and the second characteristic point coordinate, and obtaining the geometric coordinate position distortion correction submodel according to the conversion parameter.
7. The utility model provides a temperature deformation measuring device based on wide-angle lens and image distortion are rectified, its characterized in that, the device is applied to high temperature wind tunnel test, includes:
the illumination module is used for illuminating the surface of the tested piece in the closed experiment cabin through an illumination light source; the tested piece is a test piece made of carbon/silicon carbide composite material applied to aerospace thermal protection;
the image acquisition module is used for acquiring an image of the surface of the tested piece through a wide-angle camera and a high-temperature-resistant observation window arranged on the closed experiment cabin; the wide-angle camera is a charge coupled device camera integrated with a wide-angle lens, and a blue filter is additionally arranged on the wide-angle lens;
the heating module is used for heating the tested piece through a heating device;
the single-point temperature measuring module is used for measuring the single-point temperature of the surface of the tested piece through the temperature measuring device;
the control module is used for carrying out distortion correction on the image of the surface of the tested piece through a distortion correction model and obtaining a deformation field of the surface of the tested piece according to the image of the surface of the tested piece after the distortion correction; obtaining a temperature field of the surface of the tested piece according to the single-point temperature of the surface of the tested piece and the image of the surface of the tested piece after distortion correction;
the distortion correction model includes: a geometric coordinate position distortion correction sub-model; the control module is further configured to: extracting a first characteristic point coordinate from a real image of a calibration template, and extracting a second characteristic point coordinate corresponding to the first characteristic point coordinate from a distorted image collected by a wide-angle camera; and obtaining a conversion parameter between a distorted image coordinate and a real image coordinate by polynomial fitting according to the first characteristic point coordinate and the second characteristic point coordinate, and obtaining the geometric coordinate position distortion correction submodel according to the conversion parameter.
8. A non-transitory computer readable storage medium having stored thereon computer program instructions, wherein the computer program instructions, when executed by a processor, implement the method of claim 6.
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