A method for constructing bridge structure contour based on fixed-axis rotation photography

Abstract

The present invention discloses a method for constructing the outline of a bridge structure based on fixed-axis rotation photography, comprising the following steps: S1, using a camera to perform zoom scanning on each segment of the bridge to obtain a plurality of image negatives; S2, performing super-resolution reconstruction of the outline of the bridge structure on blurred image negatives among the plurality of image negatives to obtain a clear bridge image negative; S3, connecting all clear bridge image negatives in sequence according to corresponding positions of the bridge segments to obtain the outline of the bridge structure. The present invention solves the problems that the traditional method will produce splicing errors, the traditional method will reduce the resolution of the outline of the bridge segment far from the camera during scanning, and the outline of the distant bridge segment will appear distorted on the negative film in the camera.

Description

Technical Field

[0001] The invention relates to a method for constructing a bridge structure outline, and in particular to a method for constructing a bridge structure outline based on fixed-axis rotation photography. Background Art

[0002] In the traditional method, when scanning each segment during the acquisition process, the field of view includes the information of three segments at the same time (the middle segment is the main acquisition unit, and part of the information of the left and right adjacent segments). Because it contains the information of multiple segments, the film of the spliced ​​segments is used in the data processing process, and fixed focus is used in the whole process, as described below:

[0003] The camera scans each segment from left to right, for example, scans segments 5, 6, and 7. And stitches them together. However, when scanning each segment, the camera's field of view spans the two adjacent segments. For example, when scanning segment 6, segments 5 and 7 will be scanned at the same time. The scanning surface of each segment will overlap with the two adjacent segments. The purpose of this overlapping part is to find the same-name points (feature points) in the overlapping part later to stitch the segments together. Finding feature points in the overlapping area to stitch the segments together will cause stitching errors.

[0004] Figures 1 to 4 The figure is a schematic diagram of the process of scanning and splicing segments 5, 6, and 7 using the traditional method. The camera is fixed-focus during the entire scanning process (when the focal length remains unchanged, the outline of the bridge structure appears larger near the camera and smaller far away. Therefore, in the distant segments such as the 1st and 12th segments, the outline of the bridge structure accounts for a smaller proportion in the film than the mid-span segments, and the outline of the non-bridge structure accounts for a larger proportion. When the frame and resolution remain unchanged, the resolution of the outline of the bridge structure will decrease, which is not conducive to the extraction of the outline. Moreover, even if it is extracted, there will be a large error).

[0005] If the span of the bridge is very large, the outline of the distant bridge segment will appear distorted on the film inside the camera, such as Figure 5 As shown in the figure, because except for the segment facing the camera, which is the normal axis photography, the rest are oblique photography, there will be a situation of "near big and far small". The situation of "near big and far small" will appear in the acquisition process and data processing process. In the acquisition process, it is to avoid the small proportion of the bridge structure outline and the low resolution of the extracted structure caused by the near big and far small; in the data processing process, it is to match the film effect collected by the camera with the actual bridge structure outline, and take corrective measures. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for constructing a bridge structure profile based on fixed-axis rotation photography to solve the following problems:

[0007] 1. The traditional method will cover 3 segments during scanning, and it will cause stitching errors when finding feature points for stitching;

[0008] 2. In the traditional method, the camera is fixed-focus during scanning, and the resolution of the outline of the bridge segment far from the camera will be reduced;

[0009] 3. The outline of the bridge segment in the distance will appear distorted on the film inside the camera.

[0010] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a method for constructing the outline of a bridge structure based on fixed-axis rotation photography, comprising the following steps:

[0011] S1. Use a camera to perform zoom scanning on each section of the bridge to obtain multiple image negatives;

[0012] S2, performing super-resolution reconstruction of the bridge structure contour on blurred image negatives among the multiple image negatives to obtain clear bridge image negatives;

[0013] S3. Connect all clear bridge image negatives in sequence according to the corresponding positions of the bridge segments to obtain the outline of the bridge structure.

[0014] Furthermore, the camera equipment in step S1 includes: a camera and a linear laser ranging light.

[0015] Furthermore, the step S1 includes the following sub-steps:

[0016] S11. Divide the bridge into multiple sections;

[0017] S12, placing the camera device in front of the center of the bridge;

[0018] S13, rotating the camera device to scan each section of the bridge to obtain multiple image negatives.

[0019] The beneficial effect of the above further scheme is that there is no overlapping part with the adjacent segments in the image scanning surface of each segment, the scanning surface of each segment is independent and can be directly spliced ​​without finding feature points for matching and splicing, thus avoiding the stitching error caused by the traditional image overlap of each segment.

[0020] Furthermore, the step S13 includes the following steps:

[0021] S131, adjusting the camera device to obtain a scanning focal length according to the distance between the camera device and the bridge segment;

[0022] S132, adjusting the focal length of the scan, and using a camera to scan a bridge segment matching the focal length to obtain an image negative;

[0023] S133, rotate the camera device to aim at the next bridge segment, and jump to step S132 until all segments are scanned to obtain multiple image negatives.

[0024] The beneficial effect of the above further scheme is that each segment adopts a different focal length, so as to meet the requirements of the proportion and resolution of the bridge structure outline in the film and truly restore the bridge structure outline.

[0025] Furthermore, the calculation formula of the focal length in step S131 is:

[0026]

[0027] In the formula

[0028] Wherein, f is the standard focal length corresponding to the currently scanned bridge segment, f1 is the scanning focal length corresponding to the next bridge segment; L is the length of the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the current scanning field of view, L1 is the length of the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the scanning field of view of the next adjacent segment; a is the length of the currently scanned bridge segment, b is the straight line length from the right side of the currently scanned bridge segment to the center of the camera lens, and c is the straight line length from the left side of the currently scanned bridge segment to the camera lens. a1 is the length of the next adjacent bridge segment to be scanned, b1 is the straight line length from the right side of the next adjacent bridge segment to the center of the camera lens, c1 is the straight line length from the left side of the next adjacent bridge segment to the center of the camera lens; b1=, θ1 is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the current scanning field of view and the c side, θ2 is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the current scanning field of view and the b side, is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the next adjacent segment scanning field of view and the c1 side, It is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the scanning field of view of the next adjacent segment and the side b1.

[0029] The beneficial effect of the above further scheme is: select short focus for the segment close to the camera lens, and select long focus for the far segment. Because the focal length of each segment is different, the proportion of the bridge structure in the frame will be different. When connecting the image sequence, the negatives of each segment cannot be directly connected. It is necessary to ensure that the change of focal length can ensure smooth subsequent connection of each segment without jagged phenomenon, such as Fig.13 and 14 .

[0030] Furthermore, the step S3 includes the following sub-steps:

[0031] S31, selecting image films whose inclination of the straight line between the scanned bridge segment and the image film during scanning is greater than the inclination threshold, and correcting the selected clear bridge image films;

[0032] S32, connecting the corrected clear bridge image negative and the uncorrected clear bridge image negative in sequence according to corresponding positions of the bridge segments to obtain a bridge structure outline.

[0033] Furthermore, the formula for correcting the clear bridge image negative in step S31 is:

[0034]

[0035] Where d1 is the lowest height of the bridge segment to be corrected in the image negative, d1 * is the height of the bridge segment after correction, b is the straight-line length from the right side of the currently scanned bridge segment to the center of the camera lens, c is the straight-line length from the left side of the currently scanned bridge segment to the center of the camera lens, a is the length of the currently scanned bridge segment, and θ is the angle between c and b.

[0036] In summary, the beneficial effects of the present invention are:

[0037] 1. The present invention divides the bridge into sections and scans only one section at a time. There is no need to find feature points for splicing. It only needs to be spliced ​​in sequence according to the bridge structure, and no splicing error will occur.

[0038] 2. The present invention calculates the focal length of each scan based on the distance between the camera device and the bridge segment. Different bridge segments have corresponding scanning focal lengths, which avoids reducing the resolution of the outline of the bridge segment far from the camera.

[0039] 3. The outline of the bridge segment in the distance will appear distorted on the film inside the camera. By correcting the distorted image outline, the outline of the bridge structure will be clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the coverage when scanning the 5th segment using the traditional scanning method;

[0041] Figure 2 This is a schematic diagram of the coverage when scanning the 6th segment using the traditional scanning method;

[0042] Figure 3 This is a schematic diagram of the coverage when scanning the 7th segment using the traditional scanning method;

[0043] Figure 4 This is a schematic diagram of the coverage range when stitching using the traditional scanning method;

[0044] Figure 5 This is a schematic diagram showing that the outline of a bridge segment far from the camera will appear distorted on the film inside the camera;

[0045] Figure 6 It is a flow chart of a method for constructing the outline of a bridge structure based on fixed-axis rotation photography;

[0046] Figure 7 It is a schematic diagram of the sections of the model bridge;

[0047] Figure 8 It is a schematic diagram of scanning the 4th segment by the method of the present invention;

[0048] Fig. 9 It is a schematic diagram of scanning the 5th, 6th and 7th sections by the method of the present invention;

[0049] Fig.10 It is a schematic diagram of scanning the third segment by the method of the present invention;

[0050] Fig.11 The spliced ​​image of the bridge profile scanned by the method of the present invention before correction;

[0051] Fig.12 Schematic diagram of the positional relationship between L1, L2 and θ during scanning by the method of the present invention;

[0052] Fig.13 This is a schematic diagram of fixed-focus image stitching;

[0053] Fig.14 It is a schematic diagram of image stitching after zoom processing;

[0054] Fig.15 A schematic diagram for connecting images that are zoomed but not corrected;

[0055] Fig.16 A schematic diagram for connecting an image for correction of zoom. DETAILED DESCRIPTION

[0056] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0057] like Figure 6As shown, a method for constructing a bridge structure profile based on fixed-axis rotation photography includes the following steps:

[0058] S1. Use a camera to perform zoom scanning on each section of the bridge to obtain multiple image negatives;

[0059] The camera equipment in step S1 includes: a camera and a linear laser ranging light.

[0060] A fixed-axis rotating camera has a linear laser rangefinder light rigidly connected at both ends of the camera's field of view. The angle between the laser lines emitted by the linear laser lights at both ends is exactly the field of view of the camera.

[0061] The function of the camera is to scan each segment of the bridge structure by rotating on a fixed axis, and finally connect each scanned segment to form a complete outline of the bridge structure.

[0062] The fixed-axis rotation direction of the camera can be scanning from left to right, from right to left, or from the middle of the bridge to both ends of the bridge. The rotation direction depends on the specific situation and is not specifically limited.

[0063] The functions of the linear laser ranging light are: first, to limit the two ends of the bridge segment. When scanning each segment, the camera film only contains the information of one segment, and no partial information of other segments appears; second, to measure the distance between the center of the camera lens and the two ends of the segment to be measured.

[0064] Step S1 includes the following sub-steps:

[0065] S11. Divide the bridge into multiple sections;

[0066] In this embodiment, the length of each segment is between 1.5m and 2m.

[0067] S12, placing the camera device in front of the center of the bridge;

[0068] S13, rotating the camera device to scan each section of the bridge to obtain multiple image negatives.

[0069] Step S13 includes the following steps:

[0070] S131, adjusting the camera device to obtain a scanning focal length according to the distance between the camera device and the bridge segment;

[0071] The calculation formula of the focal length in step S131 is:

[0072]

[0073] In the formula

[0074] Wherein, f is the standard focal length corresponding to the currently scanned bridge segment, f1 is the scanning focal length corresponding to the next bridge segment; L is the length of the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the current scanning field of view, L1 is the length of the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the scanning field of view of the next adjacent segment; a is the length of the currently scanned bridge segment, b is the straight line length from the right side of the currently scanned bridge segment to the center of the camera lens, and c is the straight line length from the left side of the currently scanned bridge segment to the camera lens. a1 is the length of the next adjacent bridge segment to be scanned, b1 is the straight line length from the right side of the next adjacent bridge segment to the center of the camera lens, c1 is the straight line length from the left side of the next adjacent bridge segment to the center of the camera lens; b1=, θ1 is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the current scanning field of view and the c side, θ2 is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the current scanning field of view and the b side, is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the next adjacent segment scanning field of view and the c1 side, is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the next adjacent segment scanning field of view and the side b1, such as Figure 8 As shown;

[0075] S132, adjusting the focal length of the scan, and using a camera to scan a bridge segment matching the focal length to obtain an image negative;

[0076] S133, rotate the camera device to aim at the next bridge segment, and jump to step S132 until all segments are scanned to obtain multiple image negatives.

[0077] In this embodiment, a suspension bridge is used as a model bridge. Figure 7 As shown in the figure, the model bridge is divided into 12 segments. The camera is placed 3m in front of the mid-span. Due to the different focal lengths of different segments, the left and right sides of the same node are not uniform when connecting the image sequence. Therefore, if the focal length f1 of segments ②-③ is selected, the focal length f2 of the adjacent segments ①-② is calculated as shown in the above formula (1). The characters in the above formula (1) are marked in Figure 8 middle.

[0078] Through the above step S1, multiple image negatives are obtained, each image negative corresponds to a segment of the bridge, and there is no overlapping part with the adjacent segments in the image scanning surface of each segment, such as Fig. 9As shown, the scanning surfaces of each segment are independent and can be directly spliced ​​without finding feature points for matching and splicing, thus avoiding the splicing error caused by the traditional image overlap of each segment.

[0079] S2, performing super-resolution reconstruction of the bridge structure contour on blurred image negatives among the multiple image negatives to obtain clear bridge image negatives;

[0080] S3. Connect all clear bridge image negatives in sequence according to the corresponding positions of the bridge segments to obtain the outline of the bridge structure.

[0081] The “all clear bridge image negatives” mentioned in step S3 include the clear bridge image negatives obtained in step S2, and the image negatives that do not require super-resolution reconstruction of the bridge structure contour in step S2.

[0082] When the camera scans a bridge structure that is far from the camera, the structure appears larger when it is near and smaller when it is far away, which results in edge distortion of the bridge structure. Therefore, the image film needs to be corrected.

[0083] Two linear laser rangefinder lights are rigidly connected to the camera, where the angle between the two linear laser rangefinder lights is equal to the field of view of the camera. The two linear laser rangefinder lights illuminate the left and right ends of the same segment respectively, and a linear profile can be constructed. Each linear laser rangefinder light can record the distance between the laser light and the end of the segment, such as Fig.10 As shown, c and b are divided into two linear laser ranging lights to measure the length of their own distance segment ends.

[0084] Fig.10 In the equation, c>b, the angle between c and b is θ, such as Fig.11 As shown, the height of the left side of the third segment in the image negative is d1, and the height of the right side is d2. a is the length of the third segment. The actual height of the bridge segment is d. In post-processing, the two ends of a segment need to be unified to avoid the two ends of the same segment being different in vertical height. The specific correction method is as follows.

[0085] Step S3 includes the following sub-steps:

[0086] S31, selecting image films whose inclination of the straight line between the scanned bridge segment and the image film during scanning is greater than the inclination threshold, and correcting the selected clear bridge image films;

[0087] S32, connecting the corrected clear bridge image negative and the uncorrected clear bridge image negative in sequence according to corresponding positions of the bridge segments to obtain a bridge structure outline.

[0088] Fig.15 Schematic diagram of the connection for zooming without correction of the image. Fig.16Schematic diagram of the connections for zoom-corrected images.

[0089] The formula for correcting the clear bridge image negative in step S31 is:

[0090]

[0091] Where d1 is the lowest height of the bridge segment to be corrected in the image negative, d1 * is the height of the bridge segment after correction, b is the straight-line length from the right side of the currently scanned bridge segment to the center of the camera lens, c is the straight-line length from the left side of the currently scanned bridge segment to the center of the camera lens, a is the length of the currently scanned bridge segment, θ is the angle between c and b, and the relationship among a, c, b, and θ is as follows: Fig.12 shown.

Claims

1. A method for constructing a bridge structure profile based on fixed-axis rotation photography, characterized in that: The following steps are involved: S1. Use a camera to perform zoom scanning on each section of the bridge to obtain multiple image negatives; The step S1 comprises the following sub-steps: S11. Divide the bridge into multiple sections; S12, placing the camera device in front of the center of the bridge; S13, rotating the camera device to scan each section of the bridge to obtain multiple image negatives; The step S13 comprises the following steps: S131, adjusting the camera device to obtain a scanning focal length according to the distance between the camera device and the bridge segment; The calculation formula of the focal length in step S131 is: In the formula Wherein, f is the standard focal length corresponding to the currently scanned bridge segment, f1 is the scanning focal length corresponding to the next bridge segment; L is the length of the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the current scanning field of view, L1 is the length of the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the scanning field of view of the next adjacent segment; a is the length of the currently scanned bridge segment, b is the straight line length from the right side of the currently scanned bridge segment to the center of the camera lens, and c is the straight line length from the left side of the currently scanned bridge segment to the camera lens. a1 is the length of the next adjacent bridge segment to be scanned, b1 is the straight line length from the right side of the next adjacent bridge segment to the center of the camera lens, c1 is the straight line length from the left side of the next adjacent bridge segment to the center of the camera lens; b1=c, θ1 is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the current scanning field of view and the c side, θ2 is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the current scanning field of view and the b side, is the angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the next adjacent segment scanning field of view and the c1 side, The angle between the midline of the triangle formed by the center of the camera lens and the two ends of the scanned bridge segment in the scanning field of view of the next adjacent segment and the side b1; S132, adjusting the focal length of the scan, and using a camera to scan a bridge segment matching the focal length to obtain an image negative; S133, rotating the camera device to aim at the next bridge segment, and jumping to step S132, until all segments are scanned to obtain multiple image negatives; S2, performing super-resolution reconstruction of the bridge structure contour on blurred image negatives among the multiple image negatives to obtain clear bridge image negatives; S3. Connect all clear bridge image negatives in sequence according to the corresponding positions of the bridge segments to obtain the outline of the bridge structure.

2. The method for constructing the outline of a bridge structure based on fixed-axis rotation photography according to claim 1, characterized in that: The camera equipment in step S1 includes: a camera and a linear laser ranging light.

3. The method for constructing the outline of a bridge structure based on fixed-axis rotation photography according to claim 1, characterized in that: The step S3 comprises the following sub-steps: S31, selecting image films whose inclination of the straight line between the scanned bridge segment and the image film during scanning is greater than the inclination threshold, and correcting the selected clear bridge image films; S32, connecting the corrected clear bridge image negative and the uncorrected clear bridge image negative in sequence according to corresponding positions of the bridge segments to obtain a bridge structure outline.

4. The method for constructing the outline of a bridge structure based on fixed-axis rotation photography according to claim 3, characterized in that: The formula for correcting the clear bridge image negative in step S31 is: Where d1 is the lowest height of the bridge segment to be corrected in the image negative, d1 * is the height of the bridge segment after correction, b is the straight-line length from the right side of the currently scanned bridge segment to the center of the camera lens, c is the straight-line length from the left side of the currently scanned bridge segment to the center of the camera lens, a is the length of the currently scanned bridge segment, and θ is the angle between c and b.

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