A construction surveying and mapping method and system based on geographic information system

Abstract

The present invention relates to the technical field of building surveying and mapping, and specifically discloses a building surveying and mapping method and system based on a geographic information system, comprising the following steps: step S1: determining a light beam coverage area, and selecting a calibration area, taking two sides in the calibration area parallel to a forward direction as the length, connecting the midpoints of the two sides to obtain a median line, and dividing the calibration area into an upper area and a lower area; step S2: gridding the calibration area, calculating the distance from each intersection to the surface of the building according to the reflection time of the laser at each intersection; calculating in real time the difference between the lower area at the current time and the upper area before a preset time interval threshold t; step S3: if the difference value is not 0, the mapping path of a drone is offset; at this time, the offset direction of the drone is obtained, and the mapping path of the drone is adjusted according to the offset direction to ensure the accuracy and continuity of the mapping.

Description

Technical Field

[0001] The present invention relates to the technical field of building surveying and mapping, and in particular to a building surveying and mapping method and system based on a geographic information system. Background Art

[0002] With the rapid development of science and technology, the use of laser surveying technology is becoming increasingly popular in the field of architectural surveying. This advanced measurement method has greatly changed the traditional architectural surveying mode with its high precision, high efficiency and non-contact characteristics.

[0003] Laser surveying technology uses laser beams to scan and measure the distance of targets, and determines the target's location information by calculating the speed of light and reflection time. This measurement method has extremely high accuracy and speed, and can complete large-area measurements in a very short time.

[0004] In existing laser mapping technology, laser radar equipment is often used on drones to indirectly obtain accurate three-dimensional data of the building surface by emitting laser beams to the surface of the building and receiving the reflected beams. The distance is calculated based on the speed of light and the flight time. However, despite the many advantages of laser mapping technology, it still faces some challenges in actual operation; among them, the stability of the drone is a key issue. Drones are easily affected by a variety of external factors when flying in the air, such as signal interference and wind changes. These factors may cause the drone to deviate from the predetermined route, thereby affecting the scanning path and data acquisition accuracy of the laser radar system. For example, when a drone encounters strong winds or unstable airflow, its attitude and position may change slightly but significantly, which is enough to cause an angular deviation between the laser beam and the target surface, ultimately resulting in an increase in the error of the measurement data. In addition, radio signal interference may also affect the communication link between the drone and the ground control station, further exacerbating the uncertainty of the flight path. Summary of the invention

[0005] The purpose of the present invention is to provide a construction surveying and mapping method and system based on a geographic information system to solve the above technical problems.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A construction surveying and mapping method based on a geographic information system comprises the following steps:

[0008] Step S1: when the laser emitting device carried by the drone is used to perform laser mapping on the surface of the building, the light beam coverage area during laser mapping is obtained, and a maximum inscribed rectangle is selected in the light beam coverage area, which is recorded as a calibration area; the forward direction of the drone during laser mapping is obtained, and the two sides in the calibration area parallel to the forward direction are taken as the length of the calibration area; the midpoints of the two lengths of the calibration area are obtained, and the two midpoints are connected to obtain a median line, and the median line divides the calibration area into an upper area and a lower area;

[0009] Step S2: gridding the calibration area to obtain a number of intersections, and obtaining the distance collected at each intersection according to the reflection time of the laser at each intersection;

[0010] The intersection points of the upper area and the lower area are numbered in the same order, and the difference value between the lower area at the current time and the upper area t time ago is obtained in real time. , where D i represents the distance collected at the i-th intersection point in the upper region, D i ´ represents the distance collected at the i-th intersection in the lower area, n is the total number of intersections in the upper area, i∈[1,n] and i is a positive integer, and t is the preset time interval threshold;

[0011] Step S3: If Dv≠0, the mapping path of the UAV is offset; at this time, the cross-sectional model of the building surface collected in the lower area at the current time is obtained, which is recorded as the current cross-sectional model; and the cross-sectional model of the building surface collected in the upper area before time t is obtained, which is recorded as the original cross-sectional model;

[0012] Compare the original section and the current section, mark a similar area on the current section, and record the area on the current section other than the similar area as a difference area; obtain a boundary line between the similar area and the difference area, and obtain two points where the boundary line intersects with the edge of the lower area, connect the two points to obtain an auxiliary line; and obtain an offset direction of the UAV based on the perpendicular bisector of the auxiliary line, and adjust the surveying and mapping path of the UAV based on the offset direction.

[0013] As a further solution of the present invention: the process of obtaining the distance collected at each intersection includes:

[0014] Record the laser emission time t0 and the laser reception time t1, and obtain the distance collected at the intersection D=(t1-t0)c / 2, where c is the propagation speed of the laser.

[0015] As a further solution of the present invention: the intersection point of the upper area or the lower area includes the intersection point of the upper area or the lower area on each edge.

[0016] As a further solution of the present invention: the process of determining the time interval threshold includes:

[0017] The length of the calibration area is recorded as L, and the flight speed v of the UAV is obtained in real time, then the time interval threshold t=(L / 2) / v.

[0018] As a further solution of the present invention: if Dv=0, it is recorded that the mapping path of the UAV has not deviated.

[0019] As a further solution of the present invention: the process of obtaining the surface model includes:

[0020] Based on laser surveying and mapping technology and geographic information, data points are obtained according to the numbers of intersections and the distances collected at the intersections, and three-dimensional point cloud data of the building surface are generated based on all the data points; a three-dimensional model of the building surface is generated based on the three-dimensional point cloud data, which is recorded as a cross-sectional model.

[0021] As a further solution of the present invention: the process of determining the similar area includes:

[0022] On the cross-sectional model, a surface composed of several adjacent data points is recorded as a region; if there is a region k, when the current cross-sectional area and the original cross-sectional area both include the region k, the region k is recorded as a candidate region; the candidate region with the largest area is recorded as a similar region.

[0023] As a further solution of the present invention: the process of adjusting the mapping path of the UAV includes:

[0024] The offset direction of the UAV is obtained according to the perpendicular bisector of the boundary line and the forward direction; a segment located in the difference area is selected from the perpendicular bisector, recorded as an auxiliary line segment, and the length of the auxiliary line segment is obtained, recorded as s; then, the UAV advances a distance s in the opposite direction of the offset direction and re-surveys.

[0025] As a further solution of the present invention: a building surveying and mapping system based on a geographic information system, comprising:

[0026] Area division module: when the laser emitting device carried by the drone is used to perform laser mapping on the surface of the building, the light beam coverage area during laser mapping is obtained, and a maximum inscribed rectangle is selected in the light beam coverage area, which is recorded as the calibration area; the forward direction of the drone during laser mapping is obtained, and the two sides in the calibration area parallel to the forward direction are taken as the length of the calibration area; the midpoints of the two lengths of the calibration area are obtained, and the two midpoints are connected to obtain the median line, which divides the calibration area into an upper area and a lower area;

[0027] Offset judgment module: grid the calibration area to obtain a number of intersections, and obtain the distance collected at each intersection according to the reflection time of the laser at each intersection;

[0028] The intersection points of the upper area and the lower area are numbered in the same order, and the difference value between the lower area at the current time and the upper area t time ago is obtained in real time. , where D i represents the distance collected at the i-th intersection point in the upper region, D i ´ represents the distance collected at the i-th intersection in the lower area, n is the total number of intersections in the upper area, i∈[1,n] and i is a positive integer, and t is the preset time interval threshold;

[0029] Offset adjustment module: If Dv≠0, the mapping path of the drone is offset; at this time, the cross-sectional model of the building surface collected in the lower area at the current time is obtained, recorded as the current cross-sectional model; and the cross-sectional model of the building surface collected in the upper area before time t is obtained, recorded as the original cross-sectional model;

[0030] Compare the original section and the current section, mark a similar area on the current section, and record the area on the current section other than the similar area as a difference area; obtain a boundary line between the similar area and the difference area, and obtain two points where the boundary line intersects with the edge of the lower area, connect the two points to obtain an auxiliary line; and obtain an offset direction of the UAV based on the perpendicular bisector of the auxiliary line, and adjust the surveying and mapping path of the UAV based on the offset direction.

[0031] Beneficial effects of the present invention:

[0032] The present invention uses a laser emitting device to accurately map the surface of a building, and combined with geographic information system (GIS) technology, it can obtain high-precision three-dimensional point cloud data. After processing, these data can generate a detailed three-dimensional model of the building surface, thereby improving the accuracy of building mapping. The present invention introduces a real-time monitoring mechanism, which can detect in real time whether the mapping path of the drone is offset by calculating the difference between the lower area at the current time and the upper area before the preset time interval threshold t. Once an offset is found, adjustments can be made immediately to ensure the stability and continuity of the mapping process. The entire mapping process is highly automated, and everything from laser mapping, data processing to path adjustment is automatically completed by the system. This not only reduces the need for manual intervention, but also improves work efficiency and reduces the possibility of human error. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below in conjunction with the accompanying drawings.

[0034] Figure 1The present invention is a flowchart of a construction surveying and mapping method and system based on a geographic information system. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] See also Figure 1 As shown, the present invention is a construction surveying and mapping method based on a geographic information system, comprising the following steps:

[0037] Step S1: when the laser emitting device carried by the drone is used to perform laser mapping on the surface of the building, the light beam coverage area during laser mapping is obtained, and a maximum inscribed rectangle is selected in the light beam coverage area, which is recorded as a calibration area; the forward direction of the drone during laser mapping is obtained, and the two sides in the calibration area parallel to the forward direction are taken as the length of the calibration area; the midpoints of the two lengths of the calibration area are obtained, and the two midpoints are connected to obtain a median line, and the median line divides the calibration area into an upper area and a lower area;

[0038] It can be understood that in the laser mapping process, the laser beam coverage area is first determined; this area is the area where the laser contacts the building surface and reflects back; the beam coverage area is generally elliptical and circular, and the maximum inscribed rectangle is the rectangle with the largest area in the beam coverage area; the larger the area of ​​the calibration area, the more accurate the calibration result;

[0039] Step S2: gridding the calibration area to obtain a number of intersections, and obtaining the distance collected at each intersection according to the reflection time of the laser at each intersection;

[0040] The intersection points of the upper area and the lower area are numbered in the same order, and the difference value between the lower area at the current time and the upper area t time ago is obtained in real time. , where D i represents the distance collected at the i-th intersection point in the upper region, D i ´ represents the distance collected at the i-th intersection in the lower area, n is the total number of intersections in the upper area, i∈[1,n] and i is a positive integer, and t is the preset time interval threshold;

[0041] It should be noted that the intersection points of the upper area and the lower area are numbered in the same order, so as to ensure the correspondence and comparability of the data; the difference value is obtained by calculating the sum of the absolute values ​​of the differences in the distances collected at the corresponding intersection points in the two areas;

[0042] As a preferred embodiment of the present invention, the process of obtaining the distance collected at each intersection includes:

[0043] Record the laser emission time t0 and the laser reception time t1, and obtain the distance collected at the intersection D=(t1-t0)c / 2, where c is the propagation speed of the laser;

[0044] It can be understood that the distance from each intersection to the building surface is calculated based on the reflection time of the laser at each intersection; this distance is calculated by measuring the time from the emission to the return of the laser, because the propagation speed of the laser is known and is generally equal to the speed of light;

[0045] As a preferred embodiment of the present invention, the intersection point of the upper region or the lower region includes the intersection point of the upper region or the lower region on each edge;

[0046] As a preferred embodiment of the present invention, the process of determining the time interval threshold includes:

[0047] The length of the calibration area is recorded as L, and the flight speed v of the UAV is obtained in real time, then the time interval threshold t=(L / 2) / v;

[0048] It can be understood that the time interval threshold is the time difference between two measurements, which is the time required for the drone to fly half the length of the calibration area;

[0049] Step S3: If Dv≠0, the mapping path of the UAV is offset; at this time, the cross-sectional model of the building surface collected in the lower area at the current time is obtained, which is recorded as the current cross-sectional model; and the cross-sectional model of the building surface collected in the upper area before time t is obtained, which is recorded as the original cross-sectional model;

[0050] Compare the original section and the current section, mark a similar area on the current section, and record the area on the current section other than the similar area as a different area; obtain a boundary line between the similar area and the different area, and obtain two points where the boundary line intersects with the edge of the lower area, connect the two points, and obtain an auxiliary line; and obtain an offset direction of the UAV according to the perpendicular bisector of the auxiliary line, and adjust the mapping path of the UAV according to the offset direction;

[0051] As a preferred embodiment of the present invention, if Dv=0, it is recorded that the mapping path of the UAV has not deviated;

[0052] It is worth noting that the angle between the offset direction and the forward direction is generally less than 90°;

[0053] As a preferred embodiment of the present invention, the process of obtaining the surface model includes:

[0054] Based on laser mapping technology and geographic information, data points are obtained according to the numbers of the intersections and the distances collected at the intersections, and three-dimensional point cloud data of the building surface is generated according to all the data points; a three-dimensional model of the building surface is generated according to the three-dimensional point cloud data, which is recorded as a cross-sectional model;

[0055] The process of determining the similar area includes:

[0056] On the cross-sectional model, a surface formed by a number of adjacent data points is recorded as a region; if there is a region k, when both the current cross-sectional area and the original cross-sectional area include the region k, the region k is recorded as a candidate region; the candidate region with the largest area is recorded as a similar region;

[0057] It can be understood that if there is a region k that is included in both the current section and the original section, then this region is called a candidate region; this means that this region has not changed significantly in the two measurements, and therefore can be used as a candidate for a similar region; among all the candidate regions, the one with the largest area is selected as the similar region; this similar region is the region that exists in both the current section and the original section and has the largest area;

[0058] The process of adjusting the drone’s mapping path includes:

[0059] According to the perpendicular median of the boundary line and the advancing direction, the offset direction of the UAV is obtained; a segment located in the difference area is selected on the perpendicular median, recorded as an auxiliary line segment, and the length of the auxiliary line segment is obtained, recorded as s; then, the UAV advances a distance s in the opposite direction of the offset direction and re-surveys;

[0060] It can be understood that the length s of the auxiliary line segment represents the distance that the UAV needs to adjust; the offset direction and adjustment distance of the UAV are determined through geometric relationships, and then this information is used to guide the flight path of the UAV to ensure the accuracy and efficiency of surveying and mapping.

[0061] A building surveying and mapping system based on a geographic information system, characterized by comprising:

[0062] Area division module: when the laser emitting device carried by the drone is used to perform laser mapping on the surface of the building, the light beam coverage area during laser mapping is obtained, and a maximum inscribed rectangle is selected in the light beam coverage area, which is recorded as the calibration area; the forward direction of the drone during laser mapping is obtained, and the two sides in the calibration area parallel to the forward direction are taken as the length of the calibration area; the midpoints of the two lengths of the calibration area are obtained, and the two midpoints are connected to obtain the median line, which divides the calibration area into an upper area and a lower area;

[0063] Offset judgment module: grid the calibration area to obtain a number of intersections, and obtain the distance collected at each intersection according to the reflection time of the laser at each intersection;

[0064] The intersection points of the upper area and the lower area are numbered in the same order, and the difference value between the lower area at the current time and the upper area t time ago is obtained in real time. , where D i represents the distance collected at the i-th intersection point in the upper region, D i ´ represents the distance collected at the i-th intersection in the lower area, n is the total number of intersections in the upper area, i∈[1,n] and i is a positive integer, and t is the preset time interval threshold;

[0065] Offset adjustment module: If Dv≠0, the mapping path of the drone is offset; at this time, the cross-sectional model of the building surface collected in the lower area at the current time is obtained, recorded as the current cross-sectional model; and the cross-sectional model of the building surface collected in the upper area before time t is obtained, recorded as the original cross-sectional model;

[0066] Compare the original section and the current section, mark a similar area on the current section, and record the area on the current section other than the similar area as a difference area; obtain a boundary line between the similar area and the difference area, and obtain two points where the boundary line intersects with the edge of the lower area, connect the two points to obtain an auxiliary line; and obtain an offset direction of the UAV based on the perpendicular bisector of the auxiliary line, and adjust the surveying and mapping path of the UAV based on the offset direction.

[0067] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A building surveying and mapping method based on geographic information system, characterized in that: The following steps are involved: Step S1: when the laser emitting device carried by the drone is used to perform laser mapping on the surface of the building, the light beam coverage area during laser mapping is obtained, and a maximum inscribed rectangle is selected in the light beam coverage area, which is recorded as a calibration area; the forward direction of the drone during laser mapping is obtained, and the two sides in the calibration area parallel to the forward direction are taken as the length of the calibration area; the midpoints of the two lengths of the calibration area are obtained, and the two midpoints are connected to obtain a median line, and the median line divides the calibration area into an upper area and a lower area; Step S2: gridding the calibration area to obtain a number of intersections, and obtaining the distance collected at each intersection according to the reflection time of the laser at each intersection; The intersection points of the upper area and the lower area are numbered in the same order, and the difference value between the lower area at the current time and the upper area t time ago is obtained in real time. , where D i represents the distance collected at the i-th intersection point in the upper region, D i ´ represents the distance collected at the i-th intersection in the lower area, n is the total number of intersections in the upper area, i∈[1,n] and i is a positive integer, and t is the preset time interval threshold; Step S3: If Dv≠0, the mapping path of the UAV is offset; at this time, the cross-sectional model of the building surface collected in the lower area at the current time is obtained, which is recorded as the current cross-sectional model; and the cross-sectional model of the building surface collected in the upper area before time t is obtained, which is recorded as the original cross-sectional model; Compare the original section and the current section, mark a similar area on the current section, and record the area on the current section other than the similar area as a different area; obtain a boundary line between the similar area and the different area, and obtain two points where the boundary line intersects with the edge of the lower area, connect the two points, and obtain an auxiliary line; and obtain an offset direction of the UAV according to the perpendicular bisector of the auxiliary line, and adjust the mapping path of the UAV according to the offset direction; In step S2, the process of determining the time interval threshold includes: The length of the calibration area is recorded as L, and the flight speed v of the UAV is obtained in real time, then the time interval threshold t=(L / 2) / v.

2. A building surveying and mapping method based on a geographic information system according to claim 1, characterized in that: In step S2, the process of obtaining the distance collected at each intersection includes: Record the laser emission time t0 and the laser reception time t1, and obtain the distance collected at the intersection D=(t1-t0)c / 2, where c is the propagation speed of the laser.

3. The building surveying and mapping method based on geographic information system according to claim 1, characterized in that: In step S2, the intersection points of the upper region or the lower region include the intersection points of the upper region or the lower region on each edge.

4. The construction surveying and mapping method based on geographic information system according to claim 1, characterized in that: In step S3, if Dv=0, it is recorded that the mapping path of the UAV has not deviated.

5. The construction surveying and mapping method based on geographic information system according to claim 1, characterized in that: In step S3, the process of obtaining the surface model includes: Based on laser surveying and mapping technology and geographic information, data points are obtained according to the numbers of intersections and the distances collected at the intersections, and three-dimensional point cloud data of the building surface are generated based on all the data points; a three-dimensional model of the building surface is generated based on the three-dimensional point cloud data, which is recorded as a cross-sectional model.

6. The construction surveying and mapping method based on geographic information system according to claim 5, characterized in that: In step S3, the process of determining the similar area includes: On the cross-sectional model, a surface composed of several adjacent data points is recorded as a region; if there is a region k, when the current cross-sectional area and the original cross-sectional area both include the region k, the region k is recorded as a candidate region; the candidate region with the largest area is recorded as a similar region.

7. The construction surveying and mapping method based on geographic information system according to claim 1, characterized in that: In step S3, the process of adjusting the mapping path of the UAV includes: The offset direction of the UAV is obtained according to the perpendicular bisector of the boundary line and the forward direction; a segment located in the difference area is selected from the perpendicular bisector, recorded as an auxiliary line segment, and the length of the auxiliary line segment is obtained, recorded as s; then, the UAV advances a distance s in the opposite direction of the offset direction and re-surveys.

8. A building surveying and mapping system based on geographic information system, characterized in that: include: Area division module: when the laser emitting device carried by the drone is used to perform laser mapping on the surface of the building, the light beam coverage area during laser mapping is obtained, and a maximum inscribed rectangle is selected in the light beam coverage area, which is recorded as the calibration area; the forward direction of the drone during laser mapping is obtained, and the two sides in the calibration area parallel to the forward direction are taken as the length of the calibration area; the midpoints of the two lengths of the calibration area are obtained, and the two midpoints are connected to obtain the median line, which divides the calibration area into an upper area and a lower area; Offset judgment module: grid the calibration area to obtain a number of intersections, and obtain the distance collected at each intersection according to the reflection time of the laser at each intersection; The intersection points of the upper area and the lower area are numbered in the same order, and the difference value between the lower area at the current time and the upper area t time ago is obtained in real time. , where D i represents the distance collected at the i-th intersection point in the upper region, D i ´ represents the distance collected at the i-th intersection in the lower area, n is the total number of intersections in the upper area, i∈[1,n] and i is a positive integer, and t is the preset time interval threshold; Offset adjustment module: If Dv≠0, the mapping path of the UAV is offset; At this time, the cross-sectional model of the building surface collected in the lower area at the current time is obtained, which is recorded as the current cross-sectional model; and the cross-sectional model of the building surface collected in the upper area before time t is obtained, which is recorded as the original cross-sectional model; Compare the original section and the current section, mark a similar area on the current section, and record the area on the current section other than the similar area as a different area; obtain a boundary line between the similar area and the different area, and obtain two points where the boundary line intersects with the edge of the lower area, connect the two points, and obtain an auxiliary line; and obtain an offset direction of the UAV according to the perpendicular bisector of the auxiliary line, and adjust the mapping path of the UAV according to the offset direction; The process of determining the time interval threshold includes: The length of the calibration area is recorded as L, and the flight speed v of the UAV is obtained in real time, then the time interval threshold t=(L / 2) / v.

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