CN115086569B - Extra-large bridge bottom image acquisition method based on networking camera - Google Patents
Extra-large bridge bottom image acquisition method based on networking camera Download PDFInfo
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Abstract
The invention discloses a networking camera-based extra-large bridge bottom image acquisition method, wherein a networking camera is formed by connecting N cameras in parallel to acquire tail ends, and is fixedly arranged on an extra-large bridge bottom overhaul platform, the optimal acquisition position and the installation angle of the camera are planned along the bridge width direction according to the structure of the extra-large bridge bottom and the overhaul platform, acquisition site planning is further carried out along the bridge length direction, the movement of a networking camera overhaul platform in the bridge length direction is controlled through a driving system of the overhaul platform, and non-contact acquisition is carried out on apparent image data of the extra-large bridge bottom, so that automatic full-coverage image acquisition of the bridge bottom is realized.
Description
Technical Field
The invention belongs to the field of bridge detection, and particularly provides a method for acquiring an extra-large bridge bottom image based on a networking camera.
Background
Bridge detection becomes a main technical means for safe maintenance and normal operation guarantee of bridge structures, and a common detection method is used for regular inspection through manual detection and bridge inspection vehicles, but the speed of manual detection and bridge inspection vehicles is low, the efficiency is low, the condition of missed inspection can occur, timeliness is lacking, normal transportation can be influenced, the accessibility of a plurality of bridges is poor, the personnel safety risk is high, and the influence of factors such as severe environment is high, so that high-frequency inspection is difficult to maintain.
With the continuous updating of bridge detection technology means, various nondestructive detection methods such as acoustic emission detection, ultrasonic detection, laser detection and the like appear later, but instruments used in the detection are expensive, and the measurement range has certain limitation and cannot meet the requirements of bridge detection. The CCD camera sensor has the characteristics of low price, visual image data, convenient installation, non-contact and the like, and the CCD camera is adopted as a bridge apparent data acquisition sensor in the years, so that an intelligent bridge detection mode based on vision becomes a research hot spot. However, for a large-span bridge, the detection area is wide, and the detection precision is ensured, and meanwhile, the full coverage acquisition is realized through the CCD camera, so that the consumption of the CCD camera is reduced, and meanwhile, the splicing difficulty of the subsequent bridge bottom pictures is also one of the research difficulties. Especially on service devices. In addition, the shooting field of view of a single camera is limited, and a high-precision camera is required to be used for expanding the detection field of view, so that the cost is high. There is therefore a need for an arrangement that combines low cost cameras instead of high precision cameras to detect the field of view. And the camera combination receives the restriction of the perspective distortion threshold, the larger the deflection angles of the cameras at the two sides are, the larger the perspective distortion of the camera combination cannot meet the perspective distortion threshold, so that the deflection angle of the camera cannot be infinitely increased.
At present, bridge maintenance platforms are installed on large-span bridges and are used for manual regular inspection, but the accessibility of inspection of many bridges is poor, the personnel safety risk is high, and the high-frequency inspection is difficult to maintain due to the influence of factors such as severe environment.
Noun interpretation:
GSD denotes the ground pixel resolution, which describes the size of one image pixel, one pixel point on the picture representing the real world size.
Disclosure of Invention
Based on the background technology, the invention provides a method for acquiring an extra-large bridge bottom image based on a networking camera. According to the structure of the bridge bottom, the networking camera acquisition device is arranged on the bridge maintenance platform to realize the comprehensive image data acquisition of the oversized bridge bottom.
The networking camera is mounted on a bridge maintenance platform, and the bridge maintenance platform is mainly used for maintaining the bottom of an extra large bridge and consists of a truss system, a driving system, an electrical control system and a track system. The suspension crane scheme is adopted to hang the bridge at the bottom of the extra large bridge in the bridge width direction, the driving mechanism is arranged on the H-shaped steel rail in an inverted mode through the steel wheels, the truss girder is connected with the driving mechanism through the portal frame, and the forward and backward movement of the bridge maintenance platform in the bridge length direction is realized under the driving of the motor.
A method for acquiring an extra-large bridge bottom image based on a networking camera comprises the following steps:
Step one, presetting a plurality of array cameras with different fields of view, wherein the array cameras consist of a plurality of identical cameras;
step two, dividing the bottom part of the extra-large bridge into a plurality of continuous acquisition sections along the bridge width direction of the extra-large bridge; according to the size of each acquisition section, arranging array cameras which are enough to cover the corresponding section and have the least number of cameras on an overhaul platform at the bottom of the oversized bridge; networking each array camera to form a networking camera; in each group of array cameras, the overlapping length of the photographing areas of the adjacent cameras along the bridge width direction is the bridge cross section overlapping amount overlapYZ; adjusting the angles of the cameras in each group of array cameras to obtain the minimum cameras which are enough to clearly obtain the bridge bottom image;
and thirdly, planning an acquisition site along the length direction of the bridge, and moving an overhaul platform carrying networking cameras according to the set acquisition site to realize automatic full-coverage image acquisition of the bottom of the oversized bridge.
Further improved, the setting method of the array camera group comprises the following steps:
1) Selecting a camera, and determining relevant parameters of the camera: the horizontal view angle of the camera is beta, the vertical view angle of the camera is alpha, and the resolution ratio of the camera is w x h; w represents the resolution in the horizontal direction; h represents resolution in the vertical direction;
2) Array camera design:
2.1 Array camera related parameters are as follows:
The array camera set is of a symmetrical structure, namely N cameras are arranged on a horizontal base, the installation positions of the cameras are symmetrical about an array camera installation center O G, O G is set as a coordinate origin, the axis is X T along the bridge width direction, the axis is Y T along the bridge length direction, and an array camera coordinate system O G-XTYTZT is established with the vertical bridge bottom upwards as a Z T axis; the N camera optical centers of the array camera are positioned on the same horizontal line, the distance between the two camera optical centers at the outermost side in the array camera is called a baseline distance baseline, an included angle between the rays of the horizontal view field at the left and right outermost sides of the horizontal direction of the array camera is set as an array camera horizontal view field angle CombFOVHorz, the included angle between the rays of the vertical view field of the array camera is called an array camera vertical view field angle CombFOVVert, which is equivalent to the vertical view field angle alpha of a single high-definition camera, the rays of the horizontal view field at the left and right outermost sides of the array camera and the rays of the vertical view field are intersected at an array camera virtual optical center point O E;OG,OE on the same straight line and perpendicular to an object space imaging area, and are intersected at an array camera view cone central point T 0;
Setting the coverage of an object-side horizontal area of an array camera as LHorz, the coverage of an object-side vertical area of the array camera as LVert, the real imaging distance of the array camera as H, the virtual imaging distance of the array camera as H E, the distance of the virtual optical center of the array camera projected to a base line as H P, the minimum value of the nearest imaging distance of the array camera as H Mmin, the horizontal GSD of the array camera as GSDHorz and the vertical GSD of the array camera as GSDVert; the array camera view cone key points comprise ：OE,T0,T1,T2,T3,T4,T5,T6,T7,T8;T0 representing projection of a virtual optical center on an object plane, T 1 T2 T3 T4 is four corner points of the whole shooting view field respectively, T 1 T4 is a vertical view field line shot at the leftmost side, T 5 is a center point of T 1 T4, T 2 T3 is a vertical view field line shot at the rightmost side, T 6 is a T 2 T3 center point, T 1 T2 is a horizontal view field line shot at the foremost side, T 7 is a center point of T 1 T2, T 3T4 is a horizontal view field line shot at the foremost side, and T 8 is a center point of T 3 T4;
The array cameras are symmetrical about an installation center O G, the installation positions and angles of the cameras on the left side and the right side are also symmetrical about O G, and the deflection angle of one side of the origin is calculated to obtain the deflection angle of the other side symmetrical to the origin; number of deflection angles n:
Setting the deflection angle of the outermost camera as K 1, the deflection angle of the secondary outer camera as K 2, and setting the deflection angle of a camera n closest to the origin of coordinates of the array camera as K n;
The distance from the intersection point of the rays of the horizontal view fields of two adjacent cameras to the base line is called the nearest imaging distance, wherein the distance H from the object plane to the base line of the array camera is larger than the nearest imaging distance; the closest imaging distance is also symmetric about O G, taking the O G left camera arrangement as an example, let the outermost camera and the next-to-outside camera horizontal field of view intersect at point O 1,2, the distance from point O 1,2 to the base line be closest imaging distance H M1, the next-to-outside camera and the next-to-outside camera horizontal field of view intersect at point O 2,3, the distance from point O 2,3 to the base line be closest imaging distance H M2, the n-th camera and the n+1th camera horizontal field of view intersect at point O n,n+1, the distance from point O n,n+1 to the base line be closest imaging distance H Mn;
2.2 The following geometrical constraint is satisfied by the arrangement of the deflection angle of the cameras in the array camera and the nearest imaging distance between the adjacent cameras:
a.
b.
c.Kn＜...＜K2＜K1；
d.HMn＜H；
e.HMn＞HMmin；
2.3 Array camera related parameter solution:
the distance from the object plane to the base line of the array camera, namely the real imaging distance of the array camera is H, the horizontal view angle beta of the single camera and the vertical view angle alpha of the single camera can be obtained through the position information of the bridge beam bottom overhaul platform and the bridge detection surface, and the base line distance baseline is obtained;
wherein the baseline distance
The solution formula of the nearest imaging distance lower limit value H Mmin of the array camera is as follows:
the array camera horizontal field angle CombFOVHorz solves the formula as:
CombFOVHorz＝2*K1+β；
The array camera vertical field angle CombFOVVert solves the formula as:
CombFOVVert＝α；
The distance from the virtual optical center of the array camera to the base line is H P, and the solving formula is as follows:
The virtual imaging distance of the array camera is H E, and the solving formula is:
HE＝H+HP；
the array camera object space horizontal area coverage LHorz solves the formula as follows:
The array camera object-space vertical area coverage LVert solves the formula as:
the array camera horizontal GSD precision GSDHorz solving formula is:
the array camera vertical GSD precision GSDVert solving formula is:
in the array camera coordinate system O G-XTYTZT, the coordinates of the array camera view cone key points are expressed as:
OE:(0,0,-HP)；
T0:(0,0,H)；
T1:
T2:
T3:
T4:
T5:
T6:
T7:
T8:
In the solving process, the deflection angle K n and the nearest imaging distance H Mn between the adjacent cameras are parameters to be solved, and the deflection angles of the array cameras formed by different numbers of the cameras and the nearest imaging distances between the adjacent two cameras are different in solving.
Further, when the array camera comprises 2,3 and 4 cameras respectively, the method for solving the deflection angles of the cameras is as follows:
3.1 2 cameras, and the default value of the nearest imaging distance H M1 of two adjacent cameras is: h M1 =0.8×h;
the distance H of the object scene is determined, the default value is adopted by H M1, and the deflection angle K 1 is solved:
3.2 Array camera composed of 3 cameras sets the default value of the nearest imaging distance H M1 of two adjacent cameras as follows: h M1 =0.8×h;
the distance H of the object scene is determined, the default value is adopted by H M1, and the deflection angle K 1 is solved:
3.3 Array camera composed of 4 cameras sets the default value of the nearest imaging distance H M1 of two adjacent cameras as follows: the default value of H M1＝0.5*H;HM2 is: h M2 =0.3×h;
the distance H of the object scene is determined, the default value is adopted by H M1,HM2, and the deflection angle K 1,K2 is solved:
k 2 solving:
K 1 solving:
Setting the point O 1',2 at which the horizontal fields of view of the outermost camera and the secondary outer camera intersect at a point O 1,2 and project to the base line, wherein the distance from the optical center O 1 of the outermost camera 1 to the optical center O 1',2 is tmp1, and the distance from the optical center O 2 of the outermost camera 2 to the optical center O 1',2 is tmp2;
If it is
If it is
Evaluating whether the currently configured camera is reasonable or not through indexes:
4) The coverage LHorz of the horizontal direction of the object space is larger than the threshold ObjSectThre of the range of the target plane, namely LHorz is larger than ObjSectThre, objSectThre, which is the range of the horizontal direction of the acquisition section, so that the acquisition range is ensured to be omitted;
5) The ratio ProjRatio of the object space unit distance to the distance projected to each camera plane needs to be greater than a threshold ProjRatioThre, namely ProjRatio is less than ProjRatioThre, so that the object space perspective distortion is ensured not to exceed a preset threshold;
ProjRatio＝tan(K1)
6) The object space sampling distance GSDHorz needs to be smaller than a threshold value, namely GSDHorz < GSDHorzThre, GSDHorzThre is a pixel precision value required by a client, so that pixel resolution is ensured;
4) H Mn＞HMmin, the closest imaging distance H Mn is greater than or equal to the closest imaging distance lower limit H Mmin;
The four conditions are met at the same time, namely the current configuration is judged to be reasonable, otherwise, the current configuration is not reasonable.
Further improvement, the step mode of each camera in the step two is as follows:
step 2.1), setting the outside allowance of the bridge cross section as outerYZ, and obtaining the overlapping amount between adjacent networking cameras as overlapYZ;
Step 2.2) calculating the range required to be shot by the section camera according to the position of the cross section ab and the allowance outerYZ on the outer side of the bridge cross section, and naming the range as a 'point and b' point, wherein a 'b' is the view field range required to be acquired by the ab section;
Step 2.3) taking the length of a 'b' as the acquisition section length, testing the networking camera configuration consisting of 2,3 and 4 cameras one by one according to outerYZ, overlapYZ parameters, calculating the installation point O G of the array camera and the installation angle mountAngle of the array camera, and taking the networking camera with the smallest total number of cameras capable of covering ab as the optimal camera configuration.
In a further improvement, in the step 2.3), when the acquisition section is parallel to the corresponding maintenance platform, the array camera is vertical and covers the acquisition section; when the acquisition section is not parallel to the corresponding maintenance platform, the installation angle of the corresponding array camera is adjusted, and the specific method is as follows:
When the section of the maintenance platform is not parallel to the YZ section of the bridge bottom, the installation angle mountAngle of the array camera needs to be calculated;
AB is the shortest straight line of the YZ cross section of the bridge bottom, and AB is the track of the array camera on the overhaul platform; ab is the acquisition range of the array camera which needs to be covered on the whole, the coordinates of a, B and A, B are known quantities, the coordinate of a is (a y,az), the coordinate of B is (B y,bz), the coordinate of A is (A y,Az), and the coordinate of B is (B y,Bz);
The linear equation l ab for ab is:
the linear equation l AB for AB is:
Calculating the midpoint c of ab:
Vertical line passing through point c as ab Intersecting with AB at pointSimultaneously satisfies the linear equations l AB and/>Will/>Substituting the linear equations l AB and/>, respectivelySolving the coordinate of O G, wherein the point O G is the midpoint of the installation of the array camera; the passing point O G is used for making a straight line parallel to the Y axis of the world coordinate system/> Vertical line of ab/>And/>The included angle of (a) is the array camera mounting angle mountAngle; the passing point O G is perpendicular to/>Vertical line/> Intersecting the ab line at/>By straight line equation/>And l ab solves the coordinates of O' G; by straight line/>And straight line/>Solving an array camera mounting angle mountAngle by an included angle alpha 3;
Straight line And straight line/>Included angle α 3: /(I)
If it isα3＝-α3；
Array camera mounting angle mountAngle: mountAngle = 90 ° + a 3
Calculating a special section installation angle mountAngle:
The acquisition section perpendicular to the XY coordinate plane is called a special section, the special section is ij, the corresponding maintenance platform section is a mounting track BC, the midpoint of BC is taken as a coordinate origin O spe, the X spe axis is taken along the bridge length direction, the Y spe axis is taken along the bridge width direction, the Z spe axis is taken upwards at the vertical bridge bottom, and a coordinate system O spe-XspeYspeZspe of the special section corresponding to the special section is established so as to Is the starting point of the special section ij,/>Is the end point of the special section ij; the outside allowance of the special section is outerZ, and the shot area is i' Zj'Z,/>As a starting point,/>Is the end point; j 'Z is the line of sight reference point under the view cone of the array camera, the point j' Z is used as the center of a circle, the point H is used as the radius, and the point/>, where the point meets the mounting track BC of the array cameraAccording to O G and a sight line reference point j' Z under the view cone, calculating a mounting angle mountAngle, setting an included angle with an O Gj'Z mounting track BC as AngleTmp1, and setting an included angle between a virtual optical center ray of the array camera and O Gj'Z as AngleTmp;
Coordinates of (c): /(I) Solution/>, can be solved by the equation of a circle
Mounting angle mountAngle: mountAngle = 90 ° -AngleTmp1-AngleTmp2.
In a further improvement, in the second step, the method for planning the array camera with the single cross section comprises the following steps:
Let the single cross section YZ direction start at a h, end at b h, length a hbh; the region to be photographed is a YZbYZ,aYZ as a starting point and b YZ as an end point; according to the set outerYZ, overlapYZ parameters, the length L YZ：LYZ＝outerYZ+ahbh + outerYZ of the area to be shot of the single cross section ab is obtained;
the field of view of single shooting of the array camera along the bridge width direction is as follows:
array camera number n YZ:
The first array camera origin of coordinates O G is located at Start Y:
the mounting interval between the array cameras is moveStep Y：moveStepY = LHorz-OverlaYZ;
after each array camera is respectively calculated, the array camera with the least total number of cameras is adopted for installation;
The networking cameras of the bridge cross section Sec ab are configured to take Start Y as the installation position of the first array camera coordinate origin O G, and then to arrange the array cameras at moveStep Y as the installation interval.
The method for planning the acquisition site along the bridge length direction comprises the following steps of:
The XZ direction of the longitudinal section of the bridge takes a v as a starting point, b v as an ending point, and the length is a vbv; setting a region to be shot in the XZ direction of the longitudinal section of the bridge as a XZbXZ,aXZ as a starting point and b XZ as an ending point; the outside allowance of the bridge vertical section is outerXZ, and the overlap amount of the bridge vertical section is overlapXZ;
total longitudinal section length L XZ：LXZ＝outerXZ+avbv + outerXZ of bridge;
The field of view of the networking camera for single shooting along the bridge length direction is as follows:
number of stations n XZ:
The initial position of the bridge longitudinal section collection is Start X:
shifting step moveStep X：moveStepX = LVert-OverlaXZ;
The vertical section of the bridge takes Start X as the acquisition starting position of a networking camera, moves along the X (bridge length) direction, moves moveStep X each time and moves n XZ times, so that the full-coverage acquisition of the bottom of the bridge is realized;
Respectively treating the beam bottom web plate, the rib plates and the bottom plate as sections to be acquired; the beam bottom overhaul platform is an overhaul device carried along the width direction of the bridge, networking cameras are arranged on the overhaul platform, beam bottom profile acquisition of a small section area in the width direction of the whole bridge is achieved, the beam bottom overhaul platform is moved along the length direction of the bridge through planning acquisition points, and image acquisition of the beam bottom of the bridge is achieved.
Drawings
FIG. 1 is a super bridge bottom access platform;
FIG. 2 is an elevation view of a beam bottom access platform of a spring bay cross-sea bridge;
FIG. 3 bottom concavity of a spring bay cross-sea bridge;
FIG. 4 is a schematic general cross-sectional view of a spring bay cross-sea bridge;
FIG. 5 is a schematic cross-sectional view of a cross-sea bridge of Quanzhou bay and a coordinate set of points;
FIG. 6 is a coordinate set of cross-sea bridge inspection vehicle section points for Quanzhou bay;
FIG. 7 is a general section networking camera configuration;
FIG. 8 is a schematic diagram of an array camera design consisting of two cameras;
FIG. 9 is a schematic diagram of an array camera design consisting of three cameras;
FIG. 10 is a schematic diagram of an array camera design of four cameras;
FIG. 11 is a schematic illustration of camera array camera deflection angle calculation;
FIG. 12 is a schematic diagram of proportional solution of object space unit distance and its projection onto each camera plane distance
FIG. 13 bridge cross section networking camera planning;
FIG. 14 networking camera installation angle calculation principle;
FIG. 15 is a special section model of the cross-sea bridge XZ of Quanzhou bay;
FIG. 16XZ special section installation angle solving schematic;
FIG. 17 is a special section view of the Quanzhou bay cross-sea bridge YZ;
FIG. 18 is a schematic view of a YZ special section networking camera configuration;
FIG. 19 web, rib, floor, and raised floor networking camera mounting points and image view coverage areas;
FIG. 20 bridge vertical section acquisition point planning;
Detailed Description
The technical scheme of the invention is specifically described below by means of specific embodiments.
The invention designs a networking camera on the existing beam bottom overhaul platform of the extra-large bridge bottom to realize the full coverage image data acquisition of the extra-large bridge bottom, wherein the beam bottom overhaul platform is shown in figure 1.
This embodiment is exemplified by a bridge spanning the sea in the spring bay. The bridge bottom of the bridge is generally composed of a web plate and a bottom plate, but the middle of the bridge is a concave surface, and the structure of the bridge bottom is divided into the web plate, the rib plates, the bottom plate and the raised bottom plate. The concave middle surface is shown in fig. 3. The spring bay cross-sea bridge is divided into 5 common cross sections along the YZ direction along the bridge width direction as shown in fig. 4. ab is the left web cross section, bc is the bottom plate cross section 1, de is the high-rise bottom plate cross section, fg is the bottom plate cross section 2, gh is the right web cross section; the cross sections ab, bc, de, fg and gh are parallel to the bridge detection platform, and the cross sections ab, bc, de, fg and gh are called as common cross sections. The beam bottom inspection vehicle is divided into AB, BC and CD3 cross sections, the coordinates of the starting point and the ending point of each cross section of the beam bridge and the beam bottom inspection platform can be obtained according to the drawing of the bridge and the beam bottom inspection platform, and the coordinates of each point are input, as shown in fig. 5 and 6.
The configuration method of the networking cameras of the common section is consistent: taking the ab cross-section as an example, as shown in fig. 7.
Step 1.1), setting the outside allowance of the bridge cross section as outerYZ, and obtaining the overlapping amount between adjacent networking cameras as overlapYZ;
step 1.2) calculating the range required to be shot by the section camera according to the position of the cross section ab and the allowance outerYZ on the outer side of the bridge cross section, and naming the range as a 'point and b' point, wherein a 'b' is the view field range required to be acquired by the ab section;
Step 1.3) taking the length of a 'b' as the acquisition section length, testing the networking camera configuration consisting of 2,3 and 4 cameras one by one according to outerYZ, overlapYZ parameters, calculating the installation point O G of the array camera and the installation angle mountAngle of the networking cameras, and taking the networking camera with the smallest total number of cameras capable of covering ab as the optimal camera configuration.
The networking camera configuration described in the step 1.3 includes the following steps:
step 1.3.1) array camera design;
Step 1.3.2) single cross-sectional array camera planning;
step 1.3.3) the installation angle of the networking camera is calculated.
The array camera is characterized in that a plurality of cameras are fixedly connected to form a group of camera systems, so that the view field can be effectively enlarged under the condition of keeping the precision of a single camera, and the installation space is saved. Networking the array camera means to combine a plurality of array cameras to realize the collection of big scene.
The array camera design of step 1.3.1 includes the steps of:
1) And selecting a proper high-definition camera according to the detection requirement (namely the detection precision, and the distance from the mounting position of the overhaul platform camera to the acquisition section, namely the real imaging distance of the array camera is H). Determining relevant parameters of the camera: the horizontal view angle of the camera is beta, the vertical view angle of the camera is alpha, and the resolution ratio of the camera is w x h;
2) Array camera design:
2.1 Array camera related parameters are as follows:
As shown in fig. 8, 9 and 10, the array camera is a symmetrical structure, N cameras are mounted on a horizontal base, the mounting positions of the cameras are symmetrical about an array camera mounting center O G, an array camera coordinate system O G-XTYTZT is established by setting O G as a coordinate origin, taking the bridge width direction as the X T axis, taking the bridge length direction as the Y T axis, and taking the vertical bridge bottom upward as the Z T axis. The N camera optical centers of the array camera are positioned on the same horizontal line, the distance between the two camera optical centers at the outermost side is called a base line distance Baseline, the included angle between the rays of the horizontal view field of the array camera at the left and right outermost sides in the horizontal direction of the array camera is called an horizontal view field angle CombFOVHorz of the array camera, the included angle between the rays of the vertical view field of the array camera is called a vertical view field angle CombFOVVert of the array camera, the vertical view field angle alpha of the single camera is equivalent, the rays of the horizontal view field of the array camera at the left and right outermost sides in the horizontal direction of the array camera and the rays of the vertical view field intersect at a virtual optical center point O E. OG,OE of the array camera on the same straight line and intersect at a center point T 0 of a view cone of the array camera perpendicular to an imaging area of the object side.
Let the coverage of the horizontal area of the object side of the array camera be LHorz, the coverage of the vertical area of the object side of the array camera be LVert, the real imaging distance of the array camera be H, the virtual imaging distance of the array camera be H E, the distance of the virtual optical center of the array camera projected to the base line be H P, the minimum imaging distance limit value H Mmin of the array camera (the minimum imaging distance of the array camera must not be less than this value, otherwise, the redundancy of the configuration resources of the camera is caused), the horizontal GSD of the array camera be GSDHorz, and the vertical GSD of the array camera be GSDVert. The array camera view cone key points comprise ：OE,T0,O1,T2,T3,T4,T5,T6,T7,T8;
The array camera is symmetrical about the installation center O G, the installation positions and angles of the cameras on the left side and the right side are also symmetrical about O G, and the deflection angle of one side of the origin is calculated to obtain the deflection angle of the other side symmetrical with the origin. Number of deflection angles n:
taking the arrangement of the cameras on the left side of the array camera origin of coordinates as an example, let the deflection angle of the outermost camera 1 be K 1, the deflection angle of the next-to-outer camera 2 be K 2, the angle of deflection of the camera n near the array camera origin of coordinates be K n.
The distance at which the ray intersection points of the horizontal fields of the two adjacent cameras project to the base line is called the closest imaging distance, below which there may be no overlapping area of the two cameras in the object plane, the closest imaging distance is also symmetrical about O G, taking the arrangement of the left camera of O G as an example, let the horizontal fields of the outermost camera 1 and the next-to-outside camera 2 intersect at a point O 1,2, the distance from the point O 1,2 to the base line be the closest imaging distance H M1, the horizontal fields of the camera 2 and the camera 3 intersect at a point O 2,3, the distance from the point O 2,3 to the base line be the closest imaging distance H M2, the horizontal fields of the camera n and the camera n+1 intersect at a point O n,n+1, and the distance from the point O n,n+1 to the base line be the closest imaging distance H Mn.
2.2 The arrangement of the array camera deflection angle and the nearest imaging distance between adjacent cameras satisfies the following geometrical constraint relation:
a.
b.
c.Kn＜...＜K2＜K1；
d.HMn＜H；
e.HMn＞HMmin。
2.3 Array camera related parameter solution:
Through the position information of the bridge beam bottom overhaul platform and the bridge detection surface, the selected high-definition camera can acquire the real imaging distance H of the array camera, the horizontal field angle beta of the single camera, the vertical field angle alpha of the single camera and the baseline distance baseline.
The solution formula of the nearest imaging distance lower limit value H Mmin of the array camera is as follows:
the array camera horizontal field angle CombFOVHorz solves the formula as:
CombFOVHorz＝2*K1+β；
The array camera vertical field angle CombFOVVert solves the formula as:
CombFOVVert＝α；
The distance from the virtual optical center of the array camera to the base line is H P, and the solving formula is as follows:
The virtual imaging distance of the array camera is H E, and the solving formula is:
HE＝H+HP；
the array camera object space horizontal area coverage LHorz solves the formula as follows:
The array camera object-space vertical area coverage LVert solves the formula as:
the array camera horizontal GSD precision GSDHorz solving formula is:
the array camera vertical GSD precision GSDVert solving formula is:
in the array camera coordinate system O G-XTYTZT, the coordinates of the array camera view cone keypoints can be expressed as:
OE:(0,0,-HP)；
T0:(0,0,H)；
T1:/>
T2:
T3:
T4:
T5:
T6:
T7:
T8:
In the solving process, the deflection angle is a parameter to be solved, and the deflection angles of the array cameras formed by different camera numbers and the nearest imaging distances of two adjacent cameras are different in solving. The invention mainly aims at an array camera formed by 2 cameras, 3 cameras and 4 cameras to make an array camera deflection angle according to actual conditions.
2.4 2, 3, 4 Cameras) solving deflection angles of the array cameras:
an array camera design schematic of 2 cameras is shown in figure 8. The default value of the nearest imaging distance H M1 of two adjacent cameras is set by an array camera consisting of 2 cameras: h M1 =0.8×h;
the distance H of the object scene is determined, the default value is adopted by H M1, and the deflection angle K 1 is solved:
a schematic diagram of an array camera design of 3 cameras is shown in fig. 9. The default value of the nearest imaging distance H M1 of two adjacent cameras is set by an array camera consisting of 3 cameras: h M1 =0.8×h;
the distance H of the object scene is determined, the default value is adopted by H M1, and the deflection angle K 1 is solved:
an array camera design schematic of 4 cameras is shown at 10. The default value of the nearest imaging distance H M1 of two adjacent cameras is set by an array camera consisting of 4 cameras: the default value of H M1＝0.5*H;HM1 is: h M2 =0.3×h;
the distance H of the object scene is determined, the default value is adopted by H M1,HM2, and the deflection angle K 1,K2 is solved:
k 2 solving:
/>
K 1 solving:
Let the point O 1',2, at which the horizontal fields of view of the outermost camera 1 and the sub-outer camera 2 intersect at a point O 1,2, be projected to the base line, the distance from the optical center O 1 of the outermost camera 1 to O 1',2 being tmp1, and the distance from the optical center O 2 of the outermost camera 2 to O 1',2 being tmp2, as shown in fig. 11;
If it is
If it is
Evaluating whether the currently configured camera is reasonable or not through indexes:
7) The coverage LHorz of the horizontal direction of the object is larger than the threshold ObjSectThre of the range of the target plane, namely LHorz > ObjSectThre, objSectThre is the range of the horizontal direction of the acquisition section, so that the acquisition range is ensured to be omitted.
8) The ratio ProjRatio of the object side unit distance to its projection to the respective camera plane distance needs to be greater than the threshold ProjRatioThre, i.e. ProjRatio < ProjRatioThre, ensuring that the object side perspective distortion is relatively small. ProjRatio is shown in figure 12.
ProjRatio＝tan(K1)
9) The object sampling distance GSDHorz needs to be smaller than a threshold value, namely GSDHorz < GSDHorzThre, GSDHorzThre is a pixel precision value required by a customer, and pixel resolution is ensured.
4) H Mn＞HMmin, the closest imaging distance H Mn is required to be greater than or equal to the closest imaging distance lower limit value H Mmin.
The four conditions are met at the same time, namely the current configuration is judged to be reasonable, otherwise, the current configuration is not reasonable.
The single cross-sectional array camera planning of step 1.3.2 includes the steps of:
As shown in fig. 13, AB is a cross section to be collected, and AB is a bridge maintenance platform mounting section. Let a single cross-section (YZ) direction start at a h and end at b h, length a hbh. The region to be photographed is a YZbYZ, aYZ as a start point and b YZ as an end point. According to outerYZ, overlapYZ parameters set in the step 1.1, the length L YZ：LYZ＝outerYZ+ahbh + outerYZ of the area to be shot of the single cross section ab can be obtained;
the field of view of single shooting of the array camera along the bridge width direction is as follows:
array camera number n YZ:
The first array camera origin of coordinates O G is located at Start Y:
the mounting interval between the array cameras is moveStep Y：moveStepY = LHorz-OverlaYZ;
The networking cameras of the bridge cross section ab are configured to be installed at the installation position of the first array camera coordinate origin O G with Start Y as the first array camera coordinate origin, and then the networking cameras are arranged at the installation interval with moveStep Y as the installation interval.
The networking camera installation angle calculation in the step 1.3.3 comprises the following steps:
When the cross section of the maintenance platform is not parallel to the cross section of the bridge girder bottom (YZ), the installation angle mountAngle of the networking camera needs to be calculated, as shown in fig. 14.
Let AB be the shortest straight line of bridge beam bottom (YZ) cross section, AB be the track of the network camera on the maintenance platform. ab is the acquisition range of the networking camera which needs to be covered on the whole, the coordinates of a, B, A and B are known quantities, the coordinate of a is (a y,az), the coordinate of B is (B y,bz), the coordinate of A is (A y,Az), and the coordinate of B is (B y,Bz).
The linear equation l ab for ab is:
the linear equation l AB for AB is:
Calculating the midpoint c of ab:
Vertical line passing through point c as ab Intersecting with AB at pointSimultaneously satisfies the linear equations l AB and/>Will/>Substituting the linear equations l AB and/>, respectivelyThe coordinates of O G can be solved. The passing point O G is used for making a straight line parallel to the Y axis of the world coordinate system/> Vertical line of ab/>And/>The included angle of (3) is the networking camera installation angle mountAngle. The passing point O G is perpendicular to/>Vertical line/> Intersecting the ab line at/>By straight line equation/>And l ab can solve for the coordinates of O' G. By straight line/>And straight lineThe networking camera installation angle mountAngle can be solved for by the included angle α 3.
Straight lineAnd straight line/>Included angle α 3: /(I)
If it isα3＝-α3；/>
Networking camera mounting angle mountAngle: mountAngle = 90 ° + a 3
And calculating ab sections, namely calculating the total number of cameras required by the array cameras consisting of 2,3 and 4 cameras one by one, and taking networking cameras capable of covering the minimum total number of cameras of the ab sections as optimal camera configuration. And setting the common section networking camera according to the steps.
The bridge bottom of the bridge of the spring bay cross-sea bridge comprises rib plates. The acquisition section perpendicular to the XY coordinate plane is called a special section, the maintenance platform and the special section are not in parallel relation, and a model diagram is shown in FIG. 15.
The method for setting the special section array camera is consistent, and the installation angles mountAngle of the special section array camera are calculated differently. The concave area of the bottom of the bridge of the cross-sea bridge of the Quanz bay is divided into an XZ special section and a YZ special section. XZ is shown in fig. 16, calculation of the installation angle mountAngle:
The special section is ij, the corresponding section of the maintenance platform is a mounting track BC, the midpoint of BC is taken as a coordinate origin O spe, the X spe axis is taken along the bridge length direction, the Y spe axis is taken along the bridge width direction, the Z spe axis is taken vertically upwards at the bridge bottom, and a coordinate system O spe-XspeYspeZspe of the special section corresponding to the special section is established so as to Is the starting point of the special section ij,/>Is the end point of the special section ij. As shown in fig. 15, the XZ special section outside margin is outerZ, the photographed area is i' Zj'Z,As a starting point,/>Is the end point. j 'Z is the line of sight reference point under the view cone of the networking camera, the point j' Z is used as the center of a circle, the point H is used as the radius, and the point/>, which is intersected with the installation track BC of the networking cameraThe mounting angle mountAngle is calculated from O G and the view-cone lower line-of-sight reference point j' Z. An included angle with the O Gj'Z mounting track BC is AngleTmp, and an included angle between the virtual optical center ray of the networking camera and O Gj'Z is AngleTmp.
Coordinates of (c): /(I)
Can be solved by the equation of the circle
Mounting angle mountAngle: mountAngle = 90 ° -AngleTmp1-AngleTmp2
The YZ special section is shown in fig. 17, the installation angle mountAngle of the networking camera is 45 degrees in the vertical view field direction, and the networking camera is set to be the same as the common section all the time, and is not repeated here, as shown in fig. 18.
The networking camera configuration of each section along the bridge width direction is planned by the method, and the networking camera installation point and image view coverage area schematic diagram of the Quanzhou bay cross sea extra large bridge web, rib plates, bottom plates and raising bottom plates are shown in fig. 19.
And arranging the configuration of networking cameras along the bridge width direction, and further planning the acquisition sites along the bridge length direction. A schematic diagram of the collection site plan for the spring bay along the bridge length direction (XZ direction) is shown in fig. 20.
The longitudinal section of the bridge takes a v as a starting point, b v as an ending point and has a length of a vbv. Let the region of the bridge vertical section to be photographed be a XZbXZ,aXZ as the starting point and b XZ as the end point. The outside margin of the bridge vertical section is outerXZ, and the overlap amount of the bridge vertical section is overlapXZ.
Total longitudinal section length L XZ：LXZ＝outerXZ+avbv + outerXZ of bridge;
The field of view of the networking camera for single shooting along the bridge length direction is as follows: />
number of stations n XZ:
The initial position of the bridge longitudinal section collection is Start X:
shifting step moveStep X：moveStepX = LVert-OverlaXZ;
and the vertical section of the bridge takes Start X as the initial position for acquisition of a networking camera, and moves along the X (bridge length) direction, and moves moveStep X and n XZ times each time, so that full-coverage image data acquisition of the bottom of the bridge of the cross sea of the spring bay is realized.
The foregoing is merely a specific guiding embodiment of the present invention, but the design concept of the present invention is not limited thereto, and any insubstantial modification of the present invention by using the concept should be construed as infringement of the protection scope of the present invention.
Claims (6)
1. The method for acquiring the bottom image of the extra-large bridge based on the networking camera is characterized by comprising the following steps of:
Step one, presetting a plurality of array cameras with different fields of view, wherein the array cameras consist of a plurality of identical cameras;
step two, dividing the bottom part of the extra-large bridge into a plurality of continuous acquisition sections along the bridge width direction of the extra-large bridge; according to the size of each acquisition section, arranging array cameras which are enough to cover the corresponding section and have the least number of cameras on an overhaul platform at the bottom of the oversized bridge; networking each array camera to form a networking camera; in each group of array cameras, the overlapping length of the photographing areas of the adjacent cameras along the bridge width direction is the bridge cross section overlapping amount overlapYZ; adjusting the angles of the cameras in each group of array cameras to obtain the minimum cameras which are enough to clearly obtain the bridge bottom image;
Step three, planning an acquisition site along the length direction of the bridge, and moving an overhaul platform carrying networking cameras according to the set acquisition site to realize automatic full-coverage image acquisition of the bottom of the oversized bridge;
the setting method of the array camera group comprises the following steps:
1) Selecting a camera, and determining relevant parameters of the camera: the horizontal view angle of the camera is beta, the vertical view angle of the camera is alpha, and the resolution ratio of the camera is w x h; w represents the resolution in the horizontal direction; h represents resolution in the vertical direction;
2) Array camera design:
2.1 Array camera related parameters are as follows:
The array camera set is of a symmetrical structure, namely N cameras are arranged on a horizontal base, the installation positions of the cameras are symmetrical about an array camera installation center O G, O G is set as a coordinate origin, the axis is X T along the bridge width direction, the axis is Y T along the bridge length direction, and an array camera coordinate system O G-XTYTZT is established with the vertical bridge bottom upwards as a Z T axis; the N camera optical centers of the array camera are positioned on the same horizontal line, the distance between the two camera optical centers at the outermost side in the array camera is called a baseline distance baseline, an included angle between the rays of the horizontal view field at the left and right outermost sides of the horizontal direction of the array camera is set as an array camera horizontal view field angle CombFOVHorz, the included angle between the rays of the vertical view field of the array camera is called an array camera vertical view field angle CombFOVVert, which is equivalent to the vertical view field angle alpha of a single high-definition camera, the rays of the horizontal view field at the left and right outermost sides of the array camera and the rays of the vertical view field are intersected at an array camera virtual optical center point O E;OG,OE on the same straight line and perpendicular to an object space imaging area, and are intersected at an array camera view cone central point T 0;
Setting the coverage of an object-side horizontal area of an array camera as LHorz, the coverage of an object-side vertical area of the array camera as LVert, the real imaging distance of the array camera as H, the virtual imaging distance of the array camera as H E, the distance of the virtual optical center of the array camera projected to a base line as H P, the minimum value of the nearest imaging distance of the array camera as H Mmin, the horizontal GSD of the array camera as GSDHorz and the vertical GSD of the array camera as GSDVert; the array camera view cone key points comprise ：OE,T0,T1,T2,T3,T4,T5,T6,T7,T8;T0 representing projection of a virtual optical center on an object plane, T 1 T2 T3 T4 is four corner points of the whole shooting view field respectively, T 1 T4 is a vertical view field line shot at the leftmost side, T 5 is a center point of T 1 T4, T 2 T3 is a vertical view field line shot at the rightmost side, T 6 is a T 2 T3 center point, T 1 T2 is a horizontal view field line shot at the foremost side, T 7 is a center point of T 1 T2, T 3 T4 is a horizontal view field line shot at the foremost side, and T 8 is a center point of T 3 T4;
The array cameras are symmetrical about an installation center O G, the installation positions and angles of the cameras on the left side and the right side are also symmetrical about O G, and the deflection angle of one side of the origin is calculated to obtain the deflection angle of the other side symmetrical to the origin; number of deflection angles n:
Setting the deflection angle of the outermost camera as K 1, the deflection angle of the secondary outer camera as K 2, and setting the deflection angle of a camera n closest to the origin of coordinates of the array camera as K n;
The distance from the intersection point of the rays of the horizontal view fields of two adjacent cameras to the base line is called the nearest imaging distance, wherein the distance H from the object plane to the base line of the array camera is larger than the nearest imaging distance; the closest imaging distance is also symmetric about O G, taking the O G left camera arrangement as an example, let the outermost camera and the next-to-outside camera horizontal field of view intersect at point O 1,2, the distance from point O 1,2 to the base line be closest imaging distance H M1, the next-to-outside camera and the next-to-outside camera horizontal field of view intersect at point O 2,3, the distance from point O 2,3 to the base line be closest imaging distance H M2, the n-th camera and the n+1th camera horizontal field of view intersect at point O n,n+1, the distance from point O n,n+1 to the base line be closest imaging distance H Mn;
2.2 The following geometrical constraint is satisfied by the arrangement of the deflection angle of the cameras in the array camera and the nearest imaging distance between the adjacent cameras:
a.
b.
c.Kn＜...＜K2＜K1；
d.HMn＜H；
e.HMn＞HMmin；
2.3 Array camera related parameter solution:
The related parameters of the array camera comprise a minimum imaging distance limit value H Mmin of the array camera, a horizontal view angle CombFOVHorz of the array camera, a vertical view angle CombFOVVert of the array camera, a distance from a virtual optical center of the array camera to a base line projected by the array camera is H P, a virtual imaging distance of the array camera is H E, an object side horizontal area coverage LHorz of the array camera, an object side vertical area coverage LVert of the array camera, a horizontal GSD precision GSDHorz of the array camera and coordinates of a cone key point of the array camera;
the distance from the object plane to the base line of the array camera, namely the real imaging distance of the array camera is H, the horizontal view angle beta of the single camera and the vertical view angle alpha of the single camera can be obtained through the position information of the bridge beam bottom overhaul platform and the bridge detection surface, and the base line distance baseline is obtained;
wherein the baseline distance
The solution formula of the nearest imaging distance lower limit value H Mmin of the array camera is as follows:
the array camera horizontal field angle CombFOVHorz solves the formula as:
CombFOVHorz＝2*K1+β；
The array camera vertical field angle CombFOVVert solves the formula as:
CombFOVVert＝α；
The distance from the virtual optical center of the array camera to the base line is H P, and the solving formula is as follows:
The virtual imaging distance of the array camera is H E, and the solving formula is:
HE＝H+HP；
the array camera object space horizontal area coverage LHorz solves the formula as follows:
The array camera object-space vertical area coverage LVert solves the formula as:
the array camera horizontal GSD precision GSDHorz solving formula is:
the array camera vertical GSD precision GSDVert solving formula is:
in the array camera coordinate system O G-XTYTZT, the coordinates of the array camera view cone key points are expressed as:
OE：(0,0,-HP)；
T0：(0，0，H)；
TI：
T2：
T3：
T4：
T5：
T6：
T7：
T8：
In the solving process, the deflection angle K n and the nearest imaging distance H Mn between the adjacent cameras are parameters to be solved, and the deflection angles of the array cameras formed by different numbers of the cameras and the nearest imaging distances between the adjacent two cameras are different in solving.
2. The method for capturing an image of the bottom of an oversized bridge based on a networking camera as claimed in claim 1, wherein the method comprises the following steps: when the array camera comprises 2,3 and 4 cameras respectively, the method for solving the deflection angles of the cameras is as follows:
3.1 2 cameras, and the default value of the nearest imaging distance H M1 of two adjacent cameras is: h M1 =0.8×h;
the distance H of the object scene is determined, the default value is adopted by H M1, and the deflection angle K 1 is solved:
3.2 Array camera composed of 3 cameras sets the default value of the nearest imaging distance H M1 of two adjacent cameras as follows: h M1 =0.8×h;
the distance H of the object scene is determined, the default value is adopted by H M1, and the deflection angle K 1 is solved:
3.3 Array camera composed of 4 cameras sets the default value of the nearest imaging distance H M1 of two adjacent cameras as follows: the default value of H M1＝0.5*H;HM2 is: h M2 =0.3×h;
the distance H of the object scene is determined, the default value is adopted by H M1,HM2, and the deflection angle K 1,K2 is solved:
k 2 solving:
K 1 solving:
setting the point O ' 1,2 at which the horizontal fields of view of the outermost camera and the secondary outer camera intersect at a point O 1,2 and project to the base line, wherein the distance from the optical center O 1 of the outermost camera 1 to the optical center O ' 1,2 is tmp1, and the distance from the optical center O 2 of the outermost camera 2 to the optical center O ' 1,2 is tmp2;
If it is
If it is
Evaluating whether the currently configured camera is reasonable or not through indexes:
1) The coverage LHorz of the horizontal direction of the object space is larger than the threshold ObjSectThre of the range of the target plane, namely LHorz is larger than ObjSectThre, objSectThre, which is the range of the horizontal direction of the acquisition section, so that the acquisition range is ensured to be omitted;
2) The ratio ProjRatio of the object space unit distance to the distance projected to each camera plane needs to be greater than a threshold ProjRatioThre, namely ProjRatio is less than ProjRatioThre, so that the object space perspective distortion is ensured not to exceed a preset threshold;
ProjRatio＝tan(K1)
3) The object space sampling distance GSDHorz needs to be smaller than a threshold value, namely GSDHorz < GSDHorzThre, GSDHorzThre is a pixel precision value required by a client, so that pixel resolution is ensured;
4) H Mn＞HMmin, the closest imaging distance H Mn is greater than or equal to the closest imaging distance lower limit H Mmin;
The four conditions are met at the same time, namely the current configuration is judged to be reasonable, otherwise, the current configuration is not reasonable.
3. The method for capturing an image of the bottom of an oversized bridge based on networking cameras as claimed in claim 2, wherein the step of each camera in the step two is as follows:
step 2.1), setting the outside allowance of the bridge cross section as outerYZ, and obtaining the overlapping amount between adjacent networking cameras as overlapYZ;
Step 2.2) calculating the range required to be shot by the section camera according to the position of the cross section ab and the allowance outerYZ on the outer side of the bridge cross section, and naming the range as a 'point and b' point, wherein a 'b' is the view field range required to be acquired by the ab section; step 2.3) taking the length of a 'b' as the acquisition section length, testing the networking camera configuration consisting of 2,3 and 4 cameras one by one according to outerYZ, overlapYZ parameters, calculating the installation point O G of the array camera and the installation angle mountAngle of the array camera, and taking the networking camera with the smallest total number of cameras capable of covering ab as the optimal camera configuration.
4. A method for capturing images of the bottom of a super bridge based on networking cameras according to claim 3, wherein in the step 2.3), the array camera is vertical and covers the capturing section when the capturing section is parallel to the corresponding maintenance platform; when the acquisition section is not parallel to the corresponding maintenance platform, the installation angle of the corresponding array camera is adjusted, and the specific method is as follows:
When the section of the maintenance platform is not parallel to the YZ section of the bridge bottom, the installation angle mountAngle of the array camera needs to be calculated;
AB is the shortest straight line of the YZ cross section of the bridge bottom, and AB is the track of the array camera on the overhaul platform; ab is the acquisition range of the array camera which needs to be covered on the whole, the coordinates of a, B and A, B are known quantities, the coordinate of a is (a y,az), the coordinate of B is (B y,bz), the coordinate of A is (A y,Az), and the coordinate of B is (B y,Bz);
The linear equation l ab for ab is:
the linear equation l AB for AB is:
Calculating the midpoint c of ab:
Vertical line passing through point c as ab Intersecting AB at a point/>Simultaneously satisfies the linear equations l AB and/>Will/>Substituting the linear equations l AB and/>, respectivelySolving the coordinate of O G, wherein the point O G is the midpoint of the installation of the array camera; the passing point O G is used for making a straight line parallel to the Y axis of the world coordinate system/>Vertical line of abAnd/>The included angle of (a) is the array camera mounting angle mountAngle; the passing point O G is perpendicular to/>Is not shown, is not shownIntersecting the ab line at/>By straight line equation/>And l ab solves the coordinates of O' G; by straight line/>And straight line/>Solving an array camera mounting angle mountAngle by an included angle alpha 3;
Straight line And straight line/>Included angle α 3: /(I)
If it isα3＝-α3；
Array camera mounting angle mountAngle: mountAngle = 90 ° + a 3
Calculating a special section installation angle mountAngle:
The acquisition section perpendicular to the XY coordinate plane is called a special section, the special section is ij, the corresponding maintenance platform section is a mounting track BC, the midpoint of BC is taken as a coordinate origin O spe, the X spe axis is taken along the bridge length direction, the Y spe axis is taken along the bridge width direction, the Z spe axis is taken upwards at the vertical bridge bottom, and a coordinate system O spe-XspeYspeZspe of the special section corresponding to the special section is established so as to Is the starting point of the special section ij,/>Is the end point of the special section ij; the outside allowance of the special section is outerZ, and the shot area is i' Zj'Z,/>As a starting point,/>Is the end point; j 'Z is the line of sight reference point under the view cone of the array camera, the point j' Z is used as the center of a circle, the point H is used as the radius, and the point/>, where the point meets the mounting track BC of the array cameraAccording to O G and a sight line reference point j' Z under the view cone, calculating a mounting angle mountAngle, setting an included angle with an O Gj'Z mounting track BC as AngleTmp1, and setting an included angle between a virtual optical center ray of the array camera and O Gj'Z as AngleTmp;
Coordinates of (c): /(I) Solution/>, can be solved by the equation of a circle
Mounting angle mountAngle: mountAngle = 90 ° -AngleTmp1-AngleTmp2.
5. A method for capturing images of the bottom of a super bridge based on networking cameras as claimed in claim 3, wherein in the second step, the method for planning the array camera for a single cross section comprises the following steps:
Let the single cross section YZ direction start at a h, end at b h, length a hbh; the region to be photographed is a YZbYZ,aYZ as a starting point and b YZ as an end point; according to the set outerYZ, overlapYZ parameters, the length L YZ：LYZ＝outerYZ+ahbh + outerYZ of the area to be shot of the single cross section ab is obtained;
the field of view of single shooting of the array camera along the bridge width direction is as follows:
array camera number n YZ:
The first array camera origin of coordinates O G is located at Start Y:
the mounting interval between the array cameras is moveStep Y：moveStepY = LHorz-OverlaYZ;
after each array camera is respectively calculated, the array camera with the least total number of cameras is adopted for installation;
The networking cameras of the bridge cross section Sec ab are configured to take Start Y as the installation position of the first array camera coordinate origin O G, and then to arrange the array cameras at moveStep Y as the installation interval.
6. The method for acquiring the bottom image of the extra-large bridge based on the networking camera as claimed in claim 1, wherein the method for planning the acquisition site along the bridge length direction comprises the following steps:
The XZ direction of the longitudinal section of the bridge takes a v as a starting point, b v as an ending point, and the length is a vbv; setting a region to be shot in the XZ direction of the longitudinal section of the bridge as a XZbXZ,aXZ as a starting point and b XZ as an ending point; the outside allowance of the bridge vertical section is outerXZ, and the overlap amount of the bridge vertical section is overlapXZ;
total longitudinal section length L XZ：LXZ＝outerXZ+avbv + outerXZ of bridge;
The field of view of the networking camera for single shooting along the bridge length direction is as follows:
number of stations n XZ:
The initial position of the bridge longitudinal section collection is Start X:
shifting step moveStep X：moveStepX = LVert-OverlaXZ;
The vertical section of the bridge takes Start X as the acquisition starting position of a networking camera, moves along the X (bridge length) direction, moves moveStep X each time and moves n XZ times, so that the full-coverage acquisition of the bottom of the bridge is realized;
Respectively treating the beam bottom web plate, the rib plates and the bottom plate as sections to be acquired; the beam bottom overhaul platform is an overhaul device carried along the width direction of the bridge, networking cameras are arranged on the overhaul platform, beam bottom profile acquisition of a small section area in the width direction of the whole bridge is achieved, the beam bottom overhaul platform is moved along the length direction of the bridge through planning acquisition points, and image acquisition of the beam bottom of the bridge is achieved.
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