A quick monitoring method for the construction progress of building main body based on drone platform

Abstract

The present invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform, comprising: obtaining the design parameters of the building; determining the optimal shooting position of the waypoint corresponding to the monitored side of the building; at set intervals, the unmanned aerial vehicle is equipped with a camera to conduct inspections and obtain the side image of the building by shooting; and the protective net area is identified from the side image of the building, thereby estimating the current construction progress of the building. The present invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform, which only obtains a small amount of images of the building through the unmanned aerial vehicle, and combines the sensor data carried by the unmanned aerial vehicle to quickly estimate the current construction progress of the building, and has the advantages of simple implementation process and low resource consumption.

Description

Technical Field

[0001] The present invention belongs to the technical field of unmanned aerial vehicles and image processing, and in particular relates to a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform. Background Art

[0002] Construction progress monitoring is an important part of construction project management. By monitoring the construction progress, it can help project managers discover problems in a timely manner and take appropriate measures to ensure that the construction process proceeds as planned. Therefore, it is of great significance.

[0003] With the development of smart mobile terminals and drone technology, some scholars have proposed a construction progress monitoring method based on oblique photography and drone technology, such as patents CN115526450A and CN202210966642.1. The core idea is to use the images obtained by drones to construct a three-dimensional real-scene model, and compare it with the BIM model with a time dimension to judge the progress of construction.

[0004] The above construction progress monitoring methods require all-round acquisition of images of construction building targets, which places high demands on the conditions for obtaining drone data. In addition, real-scene modeling is required based on image sequences, which is complex to implement and consumes a lot of resources, making it impossible to quickly realize construction progress monitoring. Summary of the invention

[0005] In view of the defects of the prior art, the present invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform, which can effectively solve the above problems.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The present invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform, comprising the following steps:

[0008] Step S1, obtaining design parameters of the building, including: geographical location information of the building, horizontal section of the building, design height of each side of the building, and actual width of the protective net used on each side;

[0009] Step S2, superimpose the horizontal section of the building to the corresponding position of the network map in proportion, determine the monitoring side of the building according to the horizontal section of the building; analyze the monitoring side of the building to determine the best shooting position V of the waypoint corresponding to the monitoring side of the building m The longitude coordinate V mx and the latitude coordinate V my ;

[0010] Step S3, determining the shooting parameters of the camera carried by the drone, including the camera focal length f and the angle α between the camera main optical axis S and the vertical line;

[0011] Step S4: every set period, the drone carries out inspection with a camera and reaches the best shooting position V of the building. m When the building is in the air, a side image of the building is obtained by shooting at different aerial photography heights according to the designed aerial photography heights, thereby obtaining multiple side images of the building;

[0012] Step S5, screening the multiple building side images, selecting the building side image with the smallest deformation as the building side image to be analyzed, and the corresponding aerial photography height is H;

[0013] Step S6, performing image analysis on the building side image screened in step S5 to obtain the construction progress of the building inspected this time, the method is:

[0014] Step S6.1, identifying a protective net area in the building silhouette image, thereby identifying a protective net outline boundary;

[0015] Step S6.2, based on the spatial relationship between the camera and the building when the building's side image is captured, estimate the current construction height H of the building i :

[0016] Step S6.2.1, obtaining the actual width L of the protective net used for monitoring the side of the building according to the design parameters of the building;

[0017] Step S6.2.2, analyzing the side image of the building to obtain the pixel width R of the protective net in the side image of the building;

[0018] Step S6.2.3, obtain the center line L of the protection net in the identified protection net outline boundary 中 ;

[0019] Step S6.2.4, the intersection of the camera's main optical axis S and the outline boundary of the protection net is point q; obtain the distance from point q to the center line L of the protection net 中 According to formula (1), the current construction height H of the building is obtained i :

[0020] H i =h+dh=H+L×dr×sinα / Rf×R×cosα / L (1)

[0021] in:

[0022] h is the actual distance from point q to the ground;

[0023] dh is the distance from point q to the center line L of the protection net 中 The actual distance;

[0024] f is the focal length of the camera;

[0025] Step S6.3, according to the design parameters of the building, obtain the design height H0 of the monitoring side of the building; the current construction height H i The ratio to the design height H0 is the current construction progress of the building monitored this time.

[0026] Preferably, in step S2, the longitude coordinate Vmx and latitude coordinate Vm of the best shooting position Vm of the waypoint y The method to determine is:

[0027] Step S2.1: The monitoring side of the building is a building monitoring line segment in the horizontal section view of the building, and the two vertices of the building monitoring line segment are: n t and n t+1 , whose coordinates are: n t (n tx , n ty ), n t+1 (n (t+1)x , n (t+1)y ) where n tx , n ty Vertex n t The longitude and latitude coordinates of n (t+1)x , n (t+1)y Vertex n t+1 Therefore, the building monitoring line segment is represented as building monitoring line segment n t n t+1 ;

[0028] Step S2.2, determine the optimal horizontal distance D for shooting at the waypoint; wherein the optimal horizontal distance D for shooting at the waypoint refers to the optimal shooting position V of the waypoint m the optimum value of the horizontal distance from the monitored side of the building;

[0029] Step S2.3, monitoring line segment n in the building t n t+1 The vertical median of the building is n t n t+1 is the best shooting horizontal distance D of the waypoint, that is, the best shooting position V of the waypoint determined m The longitude coordinate V mx and the latitude coordinate V my .

[0030] Preferably, step S2.2 is specifically:

[0031] Assume the focal length of the camera is f, and the building monitoring line segment n t nt+1 The design width of the building monitoring side is B, and the pixel width of the camera is W. p , determine the optimal horizontal distance D of the waypoint by formula (2):

[0032]

[0033] Thereby, the imaging width of the monitored side of the building in the image meets the analysis requirements.

[0034] Preferably, step S2.3 is specifically:

[0035] Step S2.3.1, determine the number of nodes passing through vertex n t and vertex n t+1 The equation of the straight line L1 where the building monitoring line segment lies is:

[0036] Y=KX-Kr tx +n ty (3)

[0037] Where: K is the slope of the straight line L1, expressed as:

[0038] K=(n (t+1)y -n ty ) / (n (t+1)x -n tx ) (4)

[0039] Step S2.3.2, building monitoring line segment n t n t+1 The midpoint of is V, and its coordinates V(V x , V y )for:

[0040]

[0041] Step S2.3.3, therefore, the equation of the perpendicular bisector L2 passing through the midpoint V and perpendicular to the straight line L1 is:

[0042]

[0043] Step S2.3.4, since the waypoint optimal shooting position V m The distance from the midpoint V is D, so the first expression shown in formula (7) is established:

[0044] D 2 =(V mx -V x ) 2 +(V my -V y ) 2 (7)

[0045] Since the perpendicular bisector L2 passes through the best shooting position V of the waypoint m Therefore, according to formula (6), the second expression shown in formula (8) is established:

[0046]

[0047] Step S2.3.5, combining the first expression and the second expression, obtain formula (9), and obtain V mx The two values ​​of V are selected from the value located outside the building. mx The value of

[0048]

[0049] Step S2.3.6, V mx Substituting into formula (8), we get V my , thus obtaining the best shooting position V of the waypoint m The longitude coordinate V mx and the latitude coordinate V my .

[0050] Preferably, in step S4, at a waypoint optimal shooting position V m , the determination method of different aerial photography heights is:

[0051] For the first shooting, the drone aerial photography height H is selected from 5 values, determined by the following formula:

[0052]

[0053] Therefore, is the first aerial photography height. Then, every 2 meters of ascent, a new aerial photography height is determined. Thus, the best shooting position V at a waypoint is m , select 5 aerial photography heights in total;

[0054] For the second and subsequent shooting, the drone aerial photography height H is selected from 5 values, determined according to the following formula:

[0055] H=H -1 +2j, j=1,...,5 (11)

[0056] Where: H -1 Take the estimated building construction height from the last inspection;

[0057] Therefore, H -1 +2 is the first aerial photography altitude, and then, every 2 meters of ascent, a new aerial photography altitude is determined, and thus the best shooting position V at a waypoint is determined. m , a total of 5 aerial photography heights are selected.

[0058] Preferably, step S6.1 is specifically as follows:

[0059] Step S6.1.1, obtaining a protective net image template E with a pixel size of b*b;

[0060] Step S6.1.2, use the protection net image template E to scan the building side image line by line, and for each scanning window W in the scanned building side image that is the same size as the protection net image template E, calculate the correlation value R between the protection net image template E and the scanning window W EW ;

[0061]

[0062] in:

[0063] E uv Represents the pixel value of the pixel point in the uth row and vth column of the protection net image template E;

[0064] W uv represents the pixel value of the pixel at the uth row and vth column of the scanning window W;

[0065] u=1, 2, ..., b, represents the u-th row;

[0066] v = 1, 2, ..., b, represents the vth row;

[0067] Step S6.1.3, preset the correlation threshold R EW-max ; For each scan window W scanned, if its correlation value R EW Less than the correlation threshold R EW-max , then the value of the pixel at the center of the scanning window W is marked as 1, otherwise it is marked as 0, thus obtaining a binary image I;

[0068] Step S6.1.4, use horizontal straight line segments to connect all pixel points marked as 1 in a row of the binary image I, and obtain multiple parallel line segments; the rectangular area covered by all parallel line segments is the extracted contour boundary of the protection net.

[0069] Preferably, after obtaining a plurality of parallel line segments, the pixel width of the protective net in the image is obtained, and according to the pixel width of the protective net in the image, the parallel line segments whose difference with the pixel width of the protective net in the image is greater than a set value are deleted.

[0070] Preferably, E uv and W uv The pixel value is determined using the following formula:

[0071] If it is a green protective net, the pixel value = 0.25R"+0.7G"+0.05B";

[0072] If it is a blue protective net, the pixel value = 0.15R"+0.3G"+0.55B";

[0073] Among them: R", G" and B" are the color component values ​​of the red, green and blue channels of the corresponding pixel points respectively.

[0074] Preferably, it also includes:

[0075] For the same building, a current construction height of the building is estimated on each monitoring side of the building; then, the current construction heights of the building estimated on each monitoring side of the building are averaged as the final estimated current construction height of the building.

[0076] The invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform, which has the following advantages:

[0077] The present invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform. Only a small amount of images of the building are obtained by the unmanned aerial vehicle. Combined with the sensor data carried by the unmanned aerial vehicle, the current construction progress of the building can be quickly estimated. This method has the advantages of simple implementation process and low resource consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 A schematic diagram of the architecture of a method for quickly monitoring the progress of building construction based on an unmanned aerial vehicle platform provided by the present invention;

[0079] Figure 2 The schematic diagram of the optimal shooting position planning of the waypoints provided by the present invention;

[0080] Figure 3 The schematic diagram of the optimal shooting position planning of waypoints for monitoring the side of a building provided by the present invention;

[0081] Figure 4 The original schematic diagram of each parallel line segment scanned in the protective net area provided by the present invention;

[0082] Figure 5 A schematic diagram of the protection net area after removing abnormal parallel line segments provided by the present invention;

[0083] Figure 6 A schematic diagram of the building construction height estimation provided by the present invention;

[0084] Figure 7 A detailed diagram of the principle of estimating the building construction height provided by the present invention. DETAILED DESCRIPTION

[0085] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0086] The present invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform. Only a small amount of images of the building are obtained by the unmanned aerial vehicle. Combined with the sensor data carried by the unmanned aerial vehicle, the current construction progress of the building can be quickly estimated. This method has the advantages of simple implementation process and low resource consumption.

[0087] The present invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform. The main idea is: determine the best waypoint for the unmanned aerial vehicle to shoot, so as to obtain a side image of the building without deformation; identify the protection net area from the side image of the building, and then obtain the pixel width R of the protection net in the side image of the building; and then combine the relative spatial relationship between the unmanned aerial vehicle and the building to obtain the height of the center line of the protection net from the ground as the current construction height of the building, and further obtain the construction progress of the building.

[0088] The present invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform, comprising the following steps:

[0089] Step S1, obtaining design parameters of the building, including: geographical location information of the building, horizontal section of the building, design height of each side of the building, and actual width of the protective net used on each side;

[0090] Step S2, superimpose the horizontal section of the building to the corresponding position of the network map in proportion, determine the monitoring side of the building according to the horizontal section of the building; analyze the monitoring side of the building to determine the best shooting position V of the waypoint corresponding to the monitoring side of the building m The longitude coordinate V mx and the latitude coordinate V my ;

[0091] In practical applications, for each building, only one monitoring side of the building can be determined during each inspection, and this monitoring side of the building can be analyzed to finally estimate the current construction height of the building. It is also possible to determine multiple monitoring sides of the same building, and simultaneously capture images of each monitoring side of the building during each inspection, so as to estimate the current construction height of the building for each monitoring side of the building; then, the current construction heights of the building estimated from the monitoring sides of each building are averaged as the final estimated current construction height of the building. This method can further improve the accuracy of the estimation of the building construction progress. Figure 2As shown in the figure, it is the schematic diagram of the best shooting position planning for waypoints; Figure 3 The figure shows the schematic diagram of the optimal shooting position planning for waypoints on the side of a building.

[0092] In the present invention, in order to obtain an ideal, moderately sized, and minimally deformed complete building silhouette image, the method of the present invention first needs to determine the best waypoint for drone photography, including the best shooting position V of the waypoint. m The longitude coordinate V mx , latitude coordinate V my , and the aerial photography height H, which is conducive to subsequent image analysis and processing. Among them, the best shooting position V of the waypoint m The longitude coordinate V mx and the latitude coordinate V my The subsequent steps S2.1 to S2.3 are used to determine the aerial photography height H. The aerial photography height H is determined by the method of step S4.

[0093] In step S2, the best shooting position V of the waypoint m The longitude coordinate V mx and the latitude coordinate V my Methods for determining Figure 3 As shown, including:

[0094] Step S2.1: The monitoring side of the building is a building monitoring line segment in the horizontal section view of the building, and the two vertices of the building monitoring line segment are: n t and n t+1 , whose coordinates are: n t (n tx , n ty ), n t+1 (n (t+1)x , n (t+1)y ) where n tx , n ty Vertex n t The longitude and latitude coordinates of n (t+1)x , n (t+1)y Vertex n t+1 Therefore, the building monitoring line segment is represented as building monitoring line segment n t n t+1 ;

[0095] Step S2.2, determine the optimal horizontal distance D for shooting at the waypoint; wherein the optimal horizontal distance D for shooting at the waypoint refers to the optimal shooting position V of the waypoint m the optimum value of the horizontal distance from the monitored side of the building;

[0096] Step S2.2 is specifically as follows:

[0097] Assume the focal length of the camera is f, and the building monitoring line segment n t n t+1 The design width of the building monitoring side is B, and the pixel width of the camera is W. p , determine the optimal horizontal distance D of the waypoint by formula (2):

[0098]

[0099] Thereby, the imaging width of the monitored side of the building in the image meets the analysis requirements.

[0100] The principle of step S2.2 is:

[0101] The pixel width of the camera is W p , in order to make the imaging width W of the monitoring side of the building on the image b In the desired ideal range, take 2 / 3W p To 1 / 3W p Between, such as Figure 2 As shown, the optimal horizontal distance D for waypoint shooting should meet the following conditions:

[0102] because So D = f·B / W b , when W b Take 1 / 3W p To 2 / 3W p When the value is, the value range of D is: Therefore, in the present invention, directly taking

[0103] Step S2.3, monitoring line segment n in the building t n t+1 The vertical median of the building is n t n t+1 is the best shooting horizontal distance D of the waypoint, that is, the best shooting position V of the waypoint determined m The longitude coordinate V mx and the latitude coordinate V my .

[0104] Step S2.3 is specifically as follows:

[0105] Step S2.3.1, determine the number of nodes passing through vertex n t and vertex n t+1 The equation of the straight line L1 where the building monitoring line segment lies is:

[0106] Y=KX-Kn tx +n ty (3)

[0107] Where: K is the slope of the straight line L1, expressed as:

[0108] K=(n (t+1)y -n ty ) / (n (t+1)x -n tx ) (4)

[0109] Step S2.3.2, building monitoring line segment n t n t+1 The midpoint of is V, and its coordinates V(V x , V y )for:

[0110]

[0111] Step S2.3.3, therefore, the equation of the perpendicular bisector L2 passing through the midpoint V and perpendicular to the straight line L1 is:

[0112]

[0113] Step S2.3.4, since the waypoint optimal shooting position V m The distance from the midpoint V is D, so the first expression shown in formula (7) is established:

[0114] D 2 =(V mx -V x ) 2 +(V my -V y ) 2 (7)

[0115] Since the perpendicular bisector L2 passes through the best shooting position V of the waypoint m Therefore, according to formula (6), the second expression shown in formula (8) is established:

[0116]

[0117] Step S2.3.5, combining the first expression and the second expression, obtain formula (9), and obtain V mx The two values ​​of V are selected from the value located outside the building. mx The value of

[0118]

[0119] Step S2.3.6, V mx Substituting into formula (8), we get V my , thus obtaining the best shooting position V of the waypoint m The longitude coordinate V mx and the latitude coordinate V my .

[0120] Step S3, determining the shooting parameters of the camera carried by the drone, including the camera focal length f and the angle α between the camera main optical axis S and the vertical line;

[0121] Step S4: every set period, the drone carries out inspection with a camera and reaches the best shooting position V of the building. m When the building is in the air, a side image of the building is obtained by shooting at different aerial photography heights according to the designed aerial photography heights, thereby obtaining multiple side images of the building;

[0122] In step S4, at a waypoint optimal shooting position V m , the determination method of different aerial photography heights is:

[0123] For the first shooting, the drone aerial photography height H is selected from 5 values, determined by the following formula:

[0124]

[0125] Therefore, is the first aerial photography height. Then, every 2 meters of ascent, a new aerial photography height is determined. Thus, the best shooting position V at a waypoint is m , select 5 aerial photography heights in total;

[0126] For the second and subsequent shooting, the drone aerial photography height H is selected from 5 values, determined according to the following formula:

[0127] H=H -1 +2j, j=1,...,5 (11)

[0128] Where: H -1 Take the estimated building construction height from the last inspection;

[0129] Therefore, H -1 +2 is the first aerial photography altitude, and then, every 2 meters of ascent, a new aerial photography altitude is determined, and thus the best shooting position V at a waypoint is determined. m , a total of 5 aerial photography heights are selected.

[0130] Step S5, screening the multiple building side images, selecting the building side image with the smallest deformation as the building side image to be analyzed, and the corresponding aerial photography height is H;

[0131] Step S6, performing image analysis on the building side image screened in step S5 to obtain the construction progress of the building inspected this time, the method is:

[0132] Step S6.1, identifying a protective net area in the building silhouette image, thereby identifying a protective net outline boundary;

[0133] Specifically, since the protective net generally has a bright color, such as green or blue, it has a clear color distinction from the building body and construction equipment. Therefore, the method of the present invention can quickly and accurately identify the protective net area in the side image of the building.

[0134] Step S6.1 is specifically as follows:

[0135] Step S6.1.1, obtaining a protective net image template E with a pixel size of b*b, for example, a size of 5×5 or 7×7.

[0136] Step S6.1.2, use the protection net image template E to scan the building side image line by line, and for each scanning window W in the scanned building side image that is the same size as the protection net image template E, calculate the correlation value R between the protection net image template E and the scanning window W EW ;

[0137]

[0138] in:

[0139] E uv Represents the pixel value of the pixel point in the uth row and vth column of the protection net image template E;

[0140] W uv represents the pixel value of the pixel at the uth row and vth column of the scanning window W;

[0141] u=1, 2, ..., b, represents the u-th row;

[0142] v = 1, 2, ..., b, represents the vth row;

[0143] In this step, as a preferred method, E uv and W uv The pixel value is determined using the following formula:

[0144] If it is a green protective net, the pixel value = 0.25R"+0.7G"+0.05B";

[0145] If it is a blue protective net, the pixel value = 0.15R"+0.3G"+0.55B";

[0146] Among them: R", G" and B" are the color component values ​​of the red, green and blue channels of the corresponding pixel points respectively.

[0147] By increasing the weight of the color component values ​​of the green or blue channels, the matching accuracy can be improved.

[0148] Step S6.1.3, preset the correlation threshold REWmax ; For each scan window W scanned, if its correlation value R EW Less than the correlation threshold R EW-max , then the value of the pixel at the center of the scanning window W is marked as 1, otherwise it is marked as 0, thus obtaining a binary image I;

[0149] Specifically, if the color of the scanning window W is closer to the color of the protective net image template E, the correlation value R EW Therefore, by presetting the correlation threshold R EW-max , and mark the pixel values ​​that are close to the color of the protection net image template E as 1.

[0150] Step S6.1.4, use horizontal straight line segments to connect all pixel points marked as 1 in a row of the binary image I, and obtain multiple parallel line segments; the rectangular area covered by all parallel line segments is the extracted contour boundary of the protection net.

[0151] In the specific implementation, after obtaining multiple parallel line segments, the pixel width of the protective net in the image is obtained, and according to the pixel width of the protective net in the image, the parallel line segments whose difference with the pixel width of the protective net in the image is greater than a set value are deleted.

[0152] Specifically, since the width of the protective net on the monitored side of the entire building remains basically the same from the beginning to the end of construction, after obtaining the pixel width of the protective net in the image, the difference between the pixel width of the protective net in the image and the length of the parallel line segment can be compared to remove the obvious abnormal line segments and ensure the accuracy of the subsequent construction progress estimation. Figure 4 As shown in, it is the original schematic diagram of each parallel line segment of the scanned protection net area; Figure 5 The figure shows the schematic diagram of the protection net area after removing abnormal parallel line segments.

[0153] Step S6.2, based on the spatial relationship between the camera and the building when the building's side image is captured, estimate the current construction height H of the building i :

[0154] Step S6.2.1, obtaining the actual width L of the protective net used for monitoring the side of the building according to the design parameters of the building;

[0155] Step S6.2.2, analyzing the side image of the building to obtain the pixel width R of the protective net in the side image of the building;

[0156] Step S6.2.3, draw the center line L of the protection net in the identified protection net outline boundary 中 ;

[0157] Step S6.2.4, the intersection of the camera's main optical axis S and the outline of the protection net is point q; read from point q to the center line L of the protection net 中 According to formula (1), the current construction height H of the building is obtained i :

[0158] H i =h+dh=H+L×dr×sinα / Rf×R×cosα / L (1)

[0159] in:

[0160] h is the actual distance from point q to the ground;

[0161] dh is the distance from point q to the center line L of the protection net 中 The actual distance;

[0162] f is the focal length of the camera;

[0163] The derivation process of formula (1) is:

[0164] See also Figure 6 and Figure 7 :

[0165] Assume that the camera is located at point O, and the distance between point O and the ground is the aerial photography height H; the intersection of the camera's main optical axis S passing through point O and the outline boundary of the protection net is point q; then the distance from point q to the center line of the protection net L is obtained 中 The actual distance dh, and the actual distance h from point q to the ground, h+dh is the current construction height of the building.

[0166] 1. Calculate dh

[0167] Draw a perpendicular line to the camera's main optical axis S through point q, which is the mapping surface of the image plane on the side of the building. Since the camera is tilted, the angle between the camera's main optical axis S and the perpendicular line is α. Therefore, the distance from point q to the center line L of the protective net is obtained through the image. 中 After the pixel distance dr is calculated, the edge where the pixel distance dr is located is located on the mapping surface, which is perpendicular to the camera's main optical axis S. Therefore, the formula is: dh = dr*K*cos(90°-α). Among them, 90°-α is the angle β in the figure.

[0168] K is the proportional factor, which is obtained by the following formula:

[0169] K = actual width of the protection net L / pixel width of the protection net in the building's silhouette image R

[0170] 2. Calculate h

[0171] Since K=f / S” and f is known, we can calculate the distance from point O to point q along the camera’s principal optical axis S, which is S”.

[0172] Draw a horizontal line through point q and a vertical line L through point O 垂 They intersect at point A; therefore, the distance from point A to the ground is equal to the actual distance h from point q to the ground.

[0173] like Figure 7 As shown, first get the distance L from point O to point A OA , the method is: L OA =S”×cosα

[0174] Therefore, h = the distance from point A to the ground = the distance from point O to the ground HL OA =HS”×cosα

[0175] 3. Calculation of h+dh:

[0176] h+dh=HS”×cosα+K×dr×cos(90°-α)

[0177] Since =f / S", the above formula can be rewritten as:

[0178] h+dh=H+K×dr×sinα-f / K×cosα

[0179] Since =L / R, the above formula can be rewritten as:

[0180] h+dh=H+L×dr×sina / Rf×R×cosα / L

[0181] Thus we get formula (1).

[0182] Step S6.3, according to the design parameters of the building, obtain the design height H0 of the monitoring side of the building; the current construction height H i The ratio to the design height H0 is the current construction progress of the building monitored this time.

[0183] The invention provides a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform, which is used for Figure 1The shown quick monitoring system for the progress of the main construction of the building includes: a drone used for inspection, the drone is equipped with a camera through a gimbal, the camera can be a digital camera, and the attitude sensor is set on the digital camera to measure the camera inclination during shooting; in order to accurately measure the height of the drone from the ground when shooting images, a satellite positioning RTK module or a microwave ranging module is used to measure its aerial photography height; the side image of the building, the camera inclination and the aerial photography height taken by the drone are transmitted to the onboard computer in real time through a data connection line; the pre-trained guard net recognition and boundary extraction module installed in the onboard computer processes the pixel width of the guard net, and then processes the building construction height estimation module to obtain the current construction height of the building, and then obtain the building construction progress. The building construction progress and the shot image are automatically organized into a web page file using the Html format and uploaded to the browsing terminal for the project manager to read.

[0184] In summary, the present invention provides a method for quickly monitoring the construction progress of a building main body based on a drone platform. Only a small amount of images of the building are obtained by the drone. Combined with the sensor data carried by the drone, the current construction progress of the building can be quickly estimated. This method has the advantages of simple implementation process and low resource consumption.

[0185] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be considered as the scope of protection of the present invention.

Claims

1. A method for quickly monitoring the construction progress of a building based on an unmanned aerial vehicle platform, characterized in that: The following steps are involved: Step S1, obtaining design parameters of the building, including: geographical location information of the building, horizontal section of the building, design height of each side of the building, and actual width of the protective net used on each side; Step S2, superimpose the horizontal section of the building to the corresponding position of the network map in proportion, determine the monitoring side of the building according to the horizontal section of the building; analyze the monitoring side of the building to determine the best shooting position V of the waypoint corresponding to the monitoring side of the building m The longitude coordinate V mx and the latitude coordinate V my ; In step S2, the best shooting position V of the waypoint m The longitude coordinate V mx and the latitude coordinate V my The method to determine is: Step S2.1: The monitoring side of the building is a building monitoring line segment in the horizontal section view of the building, and the two vertices of the building monitoring line segment are: n t and n t+1 , whose coordinates are: n t (n tx , n ty ), n t+1 (n (t+1)x , n (t+1)y ) where n tx , n ty Vertex n t The longitude and latitude coordinates of n (t+1)x , n (t+1)y Vertex n t+1 Therefore, the building monitoring line segment is represented as building monitoring line segment n t n t+1 ; Step S2.2, determine the optimal horizontal distance D for shooting at the waypoint; wherein the optimal horizontal distance D for shooting at the waypoint refers to the optimal shooting position V of the waypoint m the optimum value of the horizontal distance from the monitored side of the building; Step S2.2 is specifically as follows: Assume the focal length of the camera is f, and the building monitoring line segment n t n t+1 The design width of the building monitoring side is B, and the pixel width of the camera is W. p , determine the optimal horizontal distance D of the waypoint by formula (2): Thus, the imaging width of the monitored side of the building in the image meets the analysis requirements; Step S2.3, monitoring line segment n in the building t n t+1 The vertical median of the building is n t n t+1 is the best shooting horizontal distance D of the waypoint, that is, the best shooting position V of the waypoint determined m The longitude coordinate V mx and the latitude coordinate V my ; Step S3, determining the shooting parameters of the camera carried by the drone, including the camera focal length f and the angle α between the camera main optical axis S and the vertical line; Step S4: every set period, the drone carries out inspection with a camera and reaches the best shooting position V of the building. m When the building is in the air, a side image of the building is obtained by shooting at different aerial photography heights according to the designed aerial photography heights, thereby obtaining multiple side images of the building; Step S5, screening the multiple building side images, selecting the building side image with the smallest deformation as the building side image to be analyzed, and the corresponding aerial photography height is H; Step S6, performing image analysis on the building side image screened in step S5 to obtain the construction progress of the building inspected this time, the method is: Step S6.1, identifying a protective net area in the building silhouette image, thereby identifying a protective net outline boundary; Step S6.1 is specifically as follows: Step S6.1.1, obtaining a protective net image template E with a pixel size of b*b; Step S6.1.2, use the protection net image template E to scan the building side image line by line, and for each scanning window W in the scanned building side image that is the same size as the protection net image template E, calculate the correlation value R between the protection net image template E and the scanning window W EW ; in: E uv Represents the pixel value of the pixel point in the uth row and vth column of the protection net image template E; W uv represents the pixel value of the pixel at the uth row and vth column of the scanning window W; u=1,2,…,b, represents the u-th row; v = 1, 2, ..., b, represents the vth row; Step S6.1.3, preset the correlation threshold R EW-max ; For each scan window W scanned, if its correlation value R EW Less than the correlation threshold R EW-max , then the value of the pixel at the center of the scanning window W is marked as 1, otherwise it is marked as 0, thus obtaining a binary image I; Step S6.1.4, using horizontal straight line segments to connect all pixel points marked as 1 in a row of the binary image I, thereby obtaining multiple parallel line segments; the rectangular area covered by all parallel line segments is the extracted contour boundary of the protection net; Step S6.2, based on the spatial relationship between the camera and the building when the building's side image is captured, estimate the current construction height H of the building i : Step S6.2.1, obtaining the actual width L of the protective net used for monitoring the side of the building according to the design parameters of the building; Step S6.2.2, analyzing the side image of the building to obtain the pixel width R of the protective net in the side image of the building; Step S6.2.3, obtain the center line L of the protection net in the identified protection net outline boundary 中 ; Step S6.2.4, the intersection of the camera's main optical axis S and the outline boundary of the protection net is point q; obtain the distance from point q to the center line L of the protection net 中 According to formula (1), the current construction height H of the building is obtained i : H i =h+dh=H+L×dr×sinα / Rf×R×cosα / L (1) in: h is the actual distance from point q to the ground; dh is the distance from point q to the center line L of the protection net 中 The actual distance; f is the focal length of the camera; Step S6.3, according to the design parameters of the building, obtain the design height H0 of the monitoring side of the building; the current construction height H i The ratio to the design height H0 is the current construction progress of the building monitored this time.

2. According to claim 1, a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform is characterized in that: Step S2.3 is specifically as follows: Step S2.3.1, determine the number of nodes passing through vertex n t and vertex n t+1 The equation of the straight line L1 where the building monitoring line segment lies is: Y=KX-Kn tx +n ty (3) Where: K is the slope of the straight line L1, expressed as: K=(n (t+1)y -n ty ) / (n (t+1)x -n tx ) (4) Step S2.3.2, building monitoring line segment n t n t+1 The midpoint of is V, and its coordinates V(V x ,V y )for: Step S2.3.3, therefore, the equation of the perpendicular bisector L2 passing through the midpoint V and perpendicular to the straight line L1 is: Step S2.3.4, since the waypoint optimal shooting position V m The distance from the midpoint V is D, so the first expression shown in formula (7) is established: D 2 =(V mx -V x ) 2 +(V my -V y ) 2 (7) Since the perpendicular bisector L2 passes through the best shooting position V of the waypoint m Therefore, according to formula (6), the second expression shown in formula (8) is established: Step S2.3.5, combining the first expression and the second expression, obtain formula (9), and obtain V mx The two values ​​of V are selected from the value located outside the building. mx The value of Step S2.3.6, V mx Substituting into formula (8), we get V my , thus obtaining the best shooting position V of the waypoint m The longitude coordinate V mx and the latitude coordinate V my .

3. According to claim 1, a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform is characterized in that: In step S4, at a waypoint optimal shooting position V m , the determination method of different aerial photography heights is: For the first shooting, the drone aerial photography height H is selected from 5 values, determined by the following formula: Therefore, is the first aerial photography height. Then, every 2 meters of ascent, a new aerial photography height is determined. Thus, the best shooting position V at a waypoint is m , select 5 aerial photography heights in total; For the second and subsequent shooting, the drone aerial photography height H is selected from 5 values, determined according to the following formula: <h2 style=";text-align:left;direction:ltr">H=H<h2 style=";text-align:left;direction:ltr"> -1 <h2 style=";text-align:left;direction:ltr"> +2j,j = 1,…,5 (11) Where: H -1 Take the estimated building construction height from the last inspection; Therefore, H -1 +2 is the first aerial photography altitude, and then, every 2 meters of ascent, a new aerial photography altitude is determined, and thus the best shooting position V at a waypoint is determined. m , a total of 5 aerial photography heights are selected.

4. According to claim 1, a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform is characterized in that: After obtaining multiple parallel line segments, the pixel width of the protection net in the image is obtained, and according to the pixel width of the protection net in the image, the parallel line segments whose pixel width difference with the protection net in the image is greater than a set value are deleted.

5. According to claim 1, a method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform is characterized in that: E uv and W uv The pixel value is determined using the following formula: If it is a green protective net, the pixel value = 0.25R"+0.7G"+0.05B"; If it is a blue protective net, the pixel value = 0.15R"+0.3G"+0.55B"; Among them: R", G" and B" are the color component values ​​of the red, green and blue channels of the corresponding pixel points respectively.

6. The method for quickly monitoring the construction progress of a building main body based on an unmanned aerial vehicle platform according to claim 1 is characterized in that: Also includes: For the same building, a current construction height of the building is estimated on each monitoring side of the building; then, the current construction heights of the building estimated on each monitoring side of the building are averaged as the final estimated current construction height of the building.

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