Device and method for detecting rain seepage condition of historic building roofing board based on infrared thermal imaging

Abstract

The invention provides an ancient building roofing board rain seepage condition detection device and method based on infrared thermal imaging, the ancient building roofing board rain seepage condition detection device based on infrared thermal imaging comprises a wood board, a rectangular guide rail, a slide block, a support, a damping rotating shaft and an infrared thermal imager; the historic building roofing board rain seepage condition detection method based on infrared thermal imaging comprises the following steps: carrying out infrared thermal imaging shooting at 1-3 o'clock in the afternoon to obtain a group of overlapped area roofing board infrared thermal images; performing unified processing such as temperature range, picture format and image denoising on the infrared thermogram; performing feature extraction and conversion matrix calculation on the infrared thermogram to complete image splicing; carrying out diversified processing on the infrared thermogram, and extracting different rain seepage areas; and calculating the area and proportion of the rain seepage area on the wooden roofing board, and judging the rain seepage degree of the wooden roofing board. According to the method, the infrared thermal imaging technology is utilized, the defects of an existing historic building roofing board rain seepage detection device and method are overcome, the historic building roofing board rain seepage area and degree are accurately detected, and powerful support is provided for historic building protection.

Description

Technical Field

[0001] The invention relates to the field of nondestructive testing of ancient buildings, and in particular to a device and method for detecting rain seepage conditions of wooden lintels of ancient buildings based on infrared thermal imaging. Background Art

[0002] As a treasure of traditional Chinese culture and architectural skills, the structural composition of wooden ancient buildings demonstrates outstanding wisdom and exquisite design. As an important component of wooden ancient buildings, the roof includes wooden lookout boards, thatch, tiles and ridges. These load-bearing and covering components form a "protective umbrella" for wooden ancient buildings. The roof has been affected by the natural environment for a long time and is prone to rain seepage; at the same time, natural aging causes the performance of wood to decline, and external factors cause the wooden lookout boards to wear and increase the risk of rain seepage. The rain seepage of wooden lookout boards in ancient buildings is serious, which will increase the moisture content of wood, cause microbial growth and cause the wooden lookout boards to decay, thereby affecting the strength and stability of the wooden lookout boards, and then threatening the safety of the entire wooden structure of the ancient building. Due to the particularity of the position of the wooden lookout boards in ancient buildings, that is, the outer side of the wooden lookout boards is covered with thatch and tiles, it is difficult to detect the rain seepage from the outside. The inner side of the wooden lookout boards is mostly in a narrow ceiling. Traditional detection methods are not only difficult to detect the results, but also easy to cause certain damage to the wooden lookout boards of ancient buildings.

[0003] Infrared thermal imaging rain infiltration detection uses an infrared thermal imager to detect the surface temperature of a building, and determines whether there is rain infiltration by comparing the difference in the surface temperature of the building being tested. For wooden structures of ancient buildings, the specific heat capacity of water is greater than that of wood. Under the same thermal radiation conditions, the temperature of the rain infiltration part rises less due to the presence of water, while the temperature of dry wood rises significantly, thus showing a temperature difference on the infrared thermal image. However, the existing infrared thermal imager has a small field of view and low resolution, and cannot capture all wooden lookouts at once, and the captured infrared thermal images are not clear, which greatly reduces the efficiency and accuracy of rain infiltration detection. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a device and method for detecting rain seepage conditions of wooden lintels of ancient buildings based on infrared thermal imaging.

[0005] In a first aspect, an embodiment of the present invention provides a device for detecting rain seepage of wooden lookout boards of ancient buildings based on infrared thermal imaging, comprising: a device for detecting rain seepage of wooden lookout boards of ancient buildings, the device comprising a wooden board, a rectangular guide rail, a slider, a bracket, a damping shaft, and an infrared thermal imager;

[0006] The rectangular guide rail is fixed on the wooden board;

[0007] The slider is slidably connected to the rectangular guide rail;

[0008] The bracket is fixedly connected to the slider to support the infrared thermal imager and ensure its stability;

[0009] The damping shaft is placed in the middle of the top of the bracket to assist the infrared thermal imager in shooting at various angles;

[0010] The infrared thermal imager is installed on the damping shaft to take a group of infrared thermal images of the wooden balusters of the ancient buildings with overlapping areas;

[0011] The infrared thermal imager slides along the rectangular guide rail, and under the action of the damping shaft, shooting at various angles is achieved;

[0012] By adopting the above-mentioned implementation method, the device for detecting rain seepage conditions of wooden lookout boards of ancient buildings can make up for the limited field of view and insufficient resolution of existing rain seepage detection devices by obtaining images of wooden lookout boards from different perspectives and splicing them together to obtain a complete panoramic view of the wooden lookout boards.

[0013] In a second aspect, an embodiment of the present invention provides a method for detecting rain seepage conditions of wooden lookout boards of ancient buildings based on infrared thermal imaging, comprising: at 1:00 to 3:00 p.m. on a sunny day on the second day after the rain, infrared images of wooden lookout boards of ancient buildings are taken based on the rain seepage condition detection device of wooden lookout boards of ancient buildings, and a group of infrared thermal images of wooden lookout boards of ancient buildings with overlapping areas are taken;

[0014] The temperature range and image format of the infrared thermal image of the wooden lookout board of the ancient building are uniformly processed, and the processed image is denoised;

[0015] Performing feature extraction and conversion matrix calculation on the infrared thermal image of the wooden lookout board of the ancient building, and completing image stitching of the infrared thermal image of the wooden lookout board of the ancient building;

[0016] The infrared thermal image of the wooden fascia of the ancient building is processed in a diversified manner to extract rain seepage areas of different degrees in the image. The infrared thermal image is spliced ​​and based on the color feature clustering algorithm, the pixels of the infrared thermal image are formed into different color clusters corresponding to rain seepage areas of different degrees.

[0017] The area and proportion of the rain seepage area on the wooden planks of the ancient building are calculated to determine the degree of rain seepage of the wooden planks.

[0018] In combination with the second aspect, in a first possible implementation method of the second aspect, the infrared thermal image is shot between 1:00 and 3:00 p.m. on a sunny day on the second day after the rain; the infrared thermal image is obtained by adjusting the appropriate shooting angle of the infrared thermal imager in the ancient building wooden lookout board rain seepage condition detection device, sliding it smoothly on the rectangular guide rail and shooting a group of infrared thermal images of the ancient building wooden lookout boards with overlapping areas.

[0019] In combination with the second aspect, in a second possible implementation of the second aspect, the temperature range and image format of the infrared thermal image of the wooden fascia of the ancient building are uniformly processed, and the infrared thermal image is denoised using a median filtering method.

[0020] In combination with the second aspect, in a third possible implementation method of the second aspect, the feature extraction of the infrared thermal image includes: using a SIFT algorithm to extract features of adjacent infrared thermal images after denoising, and using a distance-based feature matching algorithm to confirm matching points; calculating a transformation matrix based on matching points, and splicing the infrared thermal images according to the transformation matrix and a weighted average method.

[0021] In combination with the second aspect, in a fourth possible implementation method of the second aspect, the diversified processing includes: through color feature clustering technology, the pixels in the image are classified according to color similarity, thereby forming different color clusters, and associating the degree of rain seepage in the infrared thermal image, that is, each cluster represents a range of similar colors, and this range corresponds to the different degrees of rain seepage conditions of the wooden lookout boards of the ancient buildings.

[0022] In combination with the second aspect, in the fifth possible implementation method of the second aspect, the clustered image is marked with different color cluster areas, and the area and proportion of the rain infiltration area are calculated according to the correspondence between the pixel coordinates and the actual physical size; by dividing the color cluster areas, the degree of rain infiltration of the wooden awnings of the ancient building is judged. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a structural schematic diagram of a device for detecting rain seepage conditions of wooden lintels of ancient buildings based on infrared thermal imaging provided by the present invention;

[0025] Figure 2 The present invention provides a flow chart of a method for detecting rain seepage conditions of wooden lintels of ancient buildings based on infrared thermal imaging.

[0026] In the figure, 1. wooden board; 2. rectangular guide rail; 3. slider; 4. bracket; 5. damping shaft; 6. infrared thermal imager. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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.

[0028] Combine the following Figure 1 and Figure 2 The invention describes a device and method for detecting rain seepage of wooden lintels of ancient buildings based on infrared thermal imaging.

[0029] like Figure 1 As shown, a device for detecting rain seepage conditions of wooden balusters of ancient buildings based on infrared thermal imaging according to an embodiment of the present invention comprises: a wooden board 1, a rectangular guide rail 2, a slider 3, a bracket 4, a damping shaft 5, and an infrared thermal imager 6.

[0030] The rectangular guide rail 2 is used to be fixed on the wooden board 1 to provide a stable sliding track for the slider 3, ensuring that the slider 2 can move smoothly and accurately in the horizontal direction;

[0031] The slider 3 is slidably connected to the rectangular guide rail 2. This connection mode enables the slider 3 to move on the rectangular guide rail 2 with high precision, low noise and high load capacity.

[0032] The bracket 4 is fixedly connected to the slider 3 to support the infrared thermal imager 6 and ensure its stability;

[0033] The damping shaft 5 is placed in the middle of the top of the bracket 4 to assist the infrared thermal imager 6 in adjusting the height in the vertical direction and the pitch angle within the range of -45° to +45° and the horizontal angle within the range of 0 to 360°, so as to facilitate the shooting of the entire wooden lookout board of the ancient building;

[0034] The infrared thermal imager 6 is installed on the damping shaft 5, and is used to take a set of infrared thermal images of the wooden fascia boards of the ancient buildings with overlapping areas;

[0035] The wooden board 1, the rectangular guide rail 2, the slider 3, the bracket 4, the damping shaft 5 and the infrared thermal imager 6 all have openings to ensure that they can be fixed to the ground or other stable supports by bolts and that any two of them can fit closely to achieve synchronous movement.

[0036] Corresponding to the device for detecting rain seepage conditions of wooden balusters of ancient buildings based on infrared thermal imaging provided in the above-mentioned embodiment, the present invention also provides an embodiment of a method for detecting rain seepage conditions of wooden balusters of ancient buildings based on infrared thermal imaging. Figure 2 The present invention provides a method flow chart of detecting rain seepage of wooden lintels of ancient buildings based on infrared thermal imaging. Figure 2 As shown, the method includes:

[0037] S101, infrared thermal imaging is performed from 1:00 to 3:00 p.m. to obtain a set of infrared thermal images of the wooden lookout boards in the overlapping areas;

[0038] S102, performing unified processing such as temperature range, image format, and image denoising on the infrared thermal image;

[0039] Use SmartView software to adjust the temperature range of the infrared thermal image to be consistent and convert the image to the same PNG format; image denoising of the infrared thermal image, including: preprocessing the infrared thermal image and using the median filtering method to denoise the infrared thermal image.

[0040] S103, performing feature extraction and conversion matrix calculation on the infrared thermal image to complete image stitching;

[0041] The SIFT algorithm is used to extract features from adjacent infrared thermal images, and a distance-based feature matching algorithm is used to calculate the Euclidean distance between the feature point descriptors in every two infrared thermal images, and the pair of feature points with the minimum distance are confirmed as matching points.

[0042] Based on the matched feature points, the transformation matrix is ​​calculated, and the infrared thermal images are spliced ​​according to the transformation matrix and the weighted average method. Since a set of infrared thermal images taken are approximately in the same plane and the movement of the infrared thermal imager is mainly translation, the affine transformation model is used to calculate the transformation matrix. Substitute multiple pairs of matching points into the equation, form a linear equation group, and solve the least squares method to obtain the parameters of the affine transformation matrix. Affine transformation formula:

[0043]

[0044] The coordinates of the matched feature point pairs in the source image are (x i y i ), the coordinates in the target image are (x′ i y′ i ), a, b, c, d, e, f are the parameters of the affine transformation matrix.

[0045] S104, performing diversified processing on the infrared thermal image to extract different rain infiltration areas;

[0046] Through color feature clustering technology, the pixels in the image are classified according to color similarity to form different color clusters, which are associated with the degree of rain seepage in the infrared thermal image. That is, each cluster represents a range of similar colors, which corresponds to the different degrees of rain seepage conditions of the wooden balusters of the ancient buildings.

[0047] According to the background temperature of the day, appropriate thresholds are set to classify image pixels into different categories, thereby determining multiple ranges. After clustering is completed, the areas represented by different color clusters are marked and classified into rain infiltration levels.

[0048] S105, calculating the area and proportion of the rain seepage area on the wooden board, and determining the rain seepage degree of the wooden board.

[0049] Based on the marking results, according to the correspondence between the image pixel coordinates and the actual physical size, the number of pixels in each rain infiltration area is counted, and combined with the actual area corresponding to a single pixel, the actual physical area and area ratio of each rain infiltration area are calculated.

[0050] The total area ratio of each infiltration area is: if the area ratio is less than 10%, it is classified as light infiltration; if the area ratio is 10% to 30%, it is classified as moderate infiltration; if the area ratio is greater than 30%, it is classified as heavy infiltration.

[0051] The invention provides an ancient building wooden plank rain seepage condition detection device and method based on infrared thermal imaging, which can realize the accurate calculation of the rain seepage area and proportion of the ancient building wooden plank; it can accurately judge the rain seepage condition of the ancient building wooden plank, and effectively serve the ancient building protection work.

[0052] The system embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for detecting rain seepage of wooden lintels of ancient buildings based on infrared thermal imaging, characterized in that: include: Wooden board, rectangular guide rail, slider, bracket, damping shaft, infrared thermal imager; The rectangular guide rail is fixed on the wooden board; The slider is slidably connected to the rectangular guide rail; The bracket is fixedly connected to the slider to support the infrared thermal imager and ensure its stability; The damping shaft is placed in the middle of the top of the bracket to assist the infrared thermal imager in shooting at various angles; The infrared thermal imager is installed on the damping shaft to take a group of infrared thermal images of the wooden balusters of the ancient buildings with overlapping areas; The infrared thermal imager slides along the rectangular guide rail, and under the action of the damping shaft, shooting at various angles is achieved; A method for detecting rain seepage conditions of wooden balusters of ancient buildings based on infrared thermal imaging, characterized in that it comprises: taking infrared images of wooden balusters of ancient buildings based on the rain seepage condition detection device of wooden balusters of ancient buildings at 1:00 to 3:00 p.m. on a sunny day on the second day after the rain, and taking a group of infrared thermal images of wooden balusters of ancient buildings with overlapping areas; The temperature range and image format of the infrared thermal image of the wooden lookout board of the ancient building are uniformly processed, and the processed image is denoised; Feature extraction and conversion matrix calculation are performed to complete the image stitching of the infrared thermal image of the wooden fascia board of the ancient building; For diversified processing, rain infiltration areas of different degrees in the image are extracted, and pixels of the infrared thermal image are formed into different color clusters corresponding to rain infiltration areas of different degrees by using a color feature clustering algorithm for the spliced ​​infrared thermal image; The area and proportion of the rain seepage area on the wooden planks of the ancient building are calculated to determine the degree of rain seepage of the wooden planks.

2. According to the method for detecting rain seepage conditions of wooden lookout boards of ancient buildings based on infrared thermal imaging according to claim 1, its characteristic taking method is as follows: adjust the appropriate shooting angle of the infrared thermal imager of the device for detecting rain seepage conditions of wooden lookout boards of ancient buildings, slide smoothly on the rectangular guide rail and shoot a group of infrared thermal images of wooden lookout boards of ancient buildings with overlapping areas.

3. The method for detecting rain seepage of wooden lintels of ancient buildings based on infrared thermal imaging according to claim 1 or 2, characterized in that: The temperature range and image format of the infrared thermal image of the wooden fascia of the ancient building are uniformly processed, and the median filtering method is used to perform image denoising on the infrared thermal image.

4. The method for detecting rain seepage of wooden lintels of ancient buildings based on infrared thermal imaging according to claim 1 or 3, characterized in that: The SIFT algorithm is used to extract the features of the adjacent infrared thermal images after denoising, and the distance-based feature matching algorithm is used to confirm the matching points; the conversion matrix is ​​calculated based on the matching points, and the infrared thermal images are spliced ​​according to the conversion matrix and the weighted average method.

5. The method for detecting rain seepage of wooden lintels of ancient buildings based on infrared thermal imaging according to claim 1 or 4, characterized in that: By adopting diversified processing and color feature clustering technology, the pixels in the image are classified according to color similarity to form different color clusters, which are associated with the degree of rain seepage in the infrared thermal image. That is, each cluster represents a range of similar colors, which corresponds to the different degrees of rain seepage in the wooden balusters of the ancient buildings.

6. The method for detecting rain seepage of wooden lintels of ancient buildings based on infrared imaging according to claim 1 or 5, characterized in that: The clustered infrared thermal image is marked with different color cluster areas, and the area and proportion of the rain infiltration area are calculated according to the correspondence between the pixel coordinates and the actual physical size; by dividing the color cluster areas, the rain infiltration degree of the wooden awnings of the ancient building is judged.

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