Land space planning topographic survey system

Abstract

The invention discloses a territorial space planning topographic survey system, and relates to the technical field of topographic survey, and the system comprises an acquisition region division module which is used for collecting a historical topographic map of a to-be-measured region, calculating the topographic complexity of each topographic survey sub-region, and determining the measurement method of each topographic survey sub-region; the measurement environment analysis module is used for collecting environment data of the topographic measurement sub-region within the data collection time of the laser radar, calculating an environment error coefficient and giving an environment error early warning; the data acquisition module is used for measuring topographic data of the topographic measurement sub-region by using an unmanned aerial vehicle carrying a laser radar, marking a fine measurement region, and carrying out two times of topographic data measurement to form complete point cloud data; and the topographic data analysis module generates a measured topographic map, compares the initial topographic map with the measured topographic map, identifies a difference part, and outputs the difference part as a land space planning change area. The change condition of the terrain can be accurately identified, and the planning layout can be more reasonably adjusted and optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of topographic surveying, and in particular to a topographic surveying system for national land space planning. Background Art

[0002] At present, topographic surveying mainly relies on a variety of technical means, including traditional geodesy, aerial photogrammetry, remote sensing technology measurement, and GPS / CORS systems. These methods have their own advantages and disadvantages, but they all have certain limitations in practical applications. For example, although the traditional geodetic method has high accuracy, it has a long operation cycle and high labor intensity; although aerial photogrammetry has high efficiency and wide coverage, it has high requirements for flight conditions and post-processing technology; remote sensing technology measurement is greatly affected by weather and ground cover; and although the GPS / CORS system can overcome adverse factors such as terrain and climate, it may still be interfered with in certain specific areas and environments. How to improve measurement efficiency while ensuring measurement accuracy is a major challenge facing current topographic surveying. Especially in large-scale national land space planning projects, how to quickly and accurately obtain terrain data has become a key factor restricting project progress.

[0003] In a Chinese invention application with application publication number CN118548821A, a high-precision measurement method for continuous changes in surface microtopography is disclosed, including first making a rectangular frame with targets pasted on all sides, taking the lower left corner of the frame as the coordinate origin, and obtaining the coordinates of each target in turn; inserting four fixed piles into the ground according to the size of the rectangular frame in the area to be measured, placing the frame on the fixed piles, and leveling the frame with a spirit level; taking photos from the front to the back perpendicular to the frame with a smartphone, and the overlap between two adjacent photos must be greater than 70%; importing the taken photos and target coordinates into image processing software, setting targets, aligning photos, generating point clouds, and then generating DEM; after taking the photos, removing the rectangular frame, keeping the fixed piles underground, and repeating the above operations at different time points according to the purpose of the test.

[0004] In the above invention application, the high-pole vegetation and the micro-topography under the forest are measured by adjusting the size of the rectangular frame, and a high-precision point cloud model and DEM of the area to be measured can be obtained through software modeling, so as to monitor the continuous changes of the surface micro-topography of the area to be measured. However, the collection method is complicated and requires continuous and uninterrupted measurement of terrain data. However, terrain data often does not change much in a short period of time. Continuous collection and processing of this data will result in a waste of resources, and the collection and processing of point cloud data are easily affected by environmental factors. Insufficient data accuracy may cause decision makers to lack sufficient basis when formulating relevant policies and plans, resulting in the scientificity and rationality of the decision being affected.

[0005] To this end, the present invention provides a land space planning topographic surveying system. Summary of the invention

[0006] 1. Technical issues to be resolved In view of the deficiencies of the prior art, the present invention provides a land space planning topographic survey system. The present invention divides the measurement area into sub-areas according to the topographic units, and clarifies the measurement method of each sub-area. For different topographic units, more suitable measurement methods and accuracy requirements can be adopted to improve the overall measurement accuracy. The environmental data of the topographic measurement sub-areas within the laser radar data collection time are collected, and the environmental error coefficient is calculated, and an environmental error warning is issued to identify the measurement error risks that may be caused by environmental factors in advance to avoid data distortion. The fine measurement area is marked, and the topographic data is measured twice to further improve the data accuracy of these areas, which helps to ensure the accuracy and reliability of the entire topographic data set. By comparing the initial topographic map with the complete topographic map, the difference part is identified and output as the land space planning change area, the changes in natural elements such as topography, landform, and vegetation coverage can be accurately identified, and the planning layout can be adjusted and optimized more reasonably, thereby solving the technical problems recorded in the background technology.

[0007] (II) Technical solution To achieve the above objectives, the present invention is implemented through the following technical solutions: a land space planning topographic survey system, comprising: The acquisition area division module is used to collect the historical topographic map of the area to be measured, divide the area to be measured evenly into topographic measurement sub-areas of equal area according to the historical topographic map, calculate the terrain complexity of each topographic measurement sub-area, and determine the measurement method of each topographic measurement sub-area; The measurement environment analysis module is used to collect environmental data of the topographic measurement sub-area within the laser radar data collection time, calculate the environmental error coefficient, and issue an environmental error warning; The data acquisition module uses a drone equipped with a laser radar to measure the topographic data of the topographic survey sub-area, builds the first point cloud database, projects the three-dimensional point cloud data in the first point cloud database onto a two-dimensional plane, and divides the two-dimensional plane into uniform point cloud grids with an area of ​​1 square meter, and calculates the complexity of each point cloud grid. , mark the fine measurement area, conduct two terrain data measurements, analyze and form the second point cloud data, and merge the second point cloud data into the first point cloud database according to the GPS coordinates to form a complete point cloud data; The terrain data analysis module generates a survey topographic map based on the complete point cloud data, compares the initial topographic map with the survey topographic map, identifies the differences, and outputs them as the changed areas of the national land space planning.

[0008] Furthermore, historical topographic maps of the area to be measured are obtained by accessing online platforms and databases such as the National Geospatial Data Cloud and Tiandi Map as the initial topographic map. GIS software (such as ArcGIS, QGIS, etc.) or programming tools (such as Python combined with the GeoPandas library) are used to divide the initial topographic map into grids of equal size. Each grid is a topographic measurement sub-area and is numbered sequentially.

[0009] Furthermore, GIS software was used to extract the number of contour lines within the topographic survey sub-area. and the elevation value of each contour line , calculate the initial terrain complexity of each topographic survey sub-area :

[0010] in, a represents the sequential number of each topographic survey sub-area, It represents the maximum value of the contour elevation value in the same topographic measurement sub-area. Indicates the minimum value of the contour elevation within the same topographic measurement sub-area.

[0011] Furthermore, according to the initial terrain complexity The topographic measurement sub-areas are sorted from large to small according to their size. The topographic measurement sub-areas in the first 30% are marked as complex terrain areas, and the lidar is set with a high sampling frequency for data collection. The bottom 30% are marked as simple terrain areas, and the lidar is set with a low sampling frequency for data collection. The remaining topographic measurement sub-areas are marked as regular terrain areas, and the lidar is set with a regular sampling frequency for data collection.

[0012] Furthermore, several detection points were randomly set in the topographic measurement sub-area, and the light intensity of each detection point was detected by a light meter, the humidity sensor detected the humidity of each detection point, and the light scattering monitor measured the total suspended particulate matter concentration in the atmosphere. After sorting, the average light intensity of each topographic measurement sub-area was obtained. , average humidity and the average total suspended particulate matter concentration .

[0013] Furthermore, the average light intensity of each topographic measurement sub-area is obtained. , average humidity and the average total suspended particulate matter concentration , calculate the environmental error coefficient :

[0014] in, Indicates the light intensity threshold of the laser radar. represents the humidity threshold of the lidar, Indicates the total suspended particulate matter concentration threshold of the lidar.

[0015] Furthermore, when the environmental error coefficient When it is greater than 0, it means that the external environment of the current topographic measurement sub-area has a great impact on the measurement accuracy of the laser rangefinder, and an environmental error warning is issued to the outside, prompting to find another time to measure the topographic measurement sub-area.

[0016] Furthermore, the laser radar sensor, IMU, GPS and other equipment are installed on the drone, and the drone is controlled to fly according to the preset route. During the flight, the laser radar continuously emits laser pulses to the ground and receives reflected signals, and records the emission time, reception time, reflection intensity of the laser pulses, and GPS and IMU data at each time. GPS provides the absolute position information of the laser radar, and the IMU records the angular attitude of the platform (including roll, pitch and yaw) to determine the precise direction of the laser radar.

[0017] The distance between the laser and the target is calculated by the emission time and reception time of the laser pulse. Combined with GPS and IMU data, each laser point is converted from the local coordinate system of the laser radar to the global coordinate system. The calculated three-dimensional coordinates (X, Y, Z) and reflection intensity information of each laser point are combined into point cloud data to build the first point cloud database.

[0018] Furthermore, the three-dimensional point cloud data in the first point cloud database is projected onto a two-dimensional plane, and the two-dimensional plane is divided into point cloud grids with a uniform area of ​​1 square meter. After numbering, the number of point clouds on each point cloud grid is counted. .

[0019] Furthermore, get the number of points on each point cloud grid , Environmental error coefficient of the point cloud grid corresponding to the topographic measurement sub-area and initial terrain complexity , calculate the complexity of each point cloud grid :

[0020] in, c Indicates the sequential number of point cloud grids in the same topographic survey sub-area.

[0021] Furthermore, when the complexity of each point cloud grid When the grid complexity is greater than 1.2 times the mean value, it means that the spatial complexity of the area corresponding to the current grid is high, and the data needs to be improved and the GPS position coordinates corresponding to the center point of the point cloud grid are output. The mean value of the grid complexity is the complexity of all point cloud grids in all terrain measurement sub-areas. The mean of .

[0022] Furthermore, all output GPS position coordinates are sorted out and marked as fine measurement areas. A drone equipped with a lidar is used to conduct two terrain data measurements on the fine measurement area. The second point cloud data is analyzed and formed. The second point cloud data is merged into the first point cloud database based on the GPS coordinates to form complete point cloud data.

[0023] Furthermore, point cloud processing software (such as CloudCompare, GlobalMapper, Lidar360, etc.) is used to classify the complete point cloud data, distinguish different categories of point cloud data such as ground points, vegetation points, and building points, extract elevation information from the classified ground point cloud, generate a digital elevation model (DEM), and use terrain surface reconstruction algorithms (such as TIN, Grid, etc.) to convert the DEM data into a terrain surface model that is easier to represent and analyze. Based on the DEM data or terrain surface model, contour lines are drawn and the measured topographic map is output.

[0024] Furthermore, the initial topographic map was georeferenced with the survey topographic map to align them precisely in spatial position. Based on the division of the topographic survey sub-areas, the number of contour lines in the topographic survey sub-areas in the survey topographic map was extracted using GIS software. and the elevation value of each contour line , calculate the measurement terrain complexity of each topographic measurement sub-area in the measurement terrain map :

[0025] in, It indicates the maximum value of the contour elevation value in the same topographic measurement sub-area in the topographic map. It indicates the minimum value of the contour elevation value in the same topographic measurement sub-area in the topographic map.

[0026] Further, the measurement terrain complexity of each topographic measurement sub-area in the measurement topographic map is obtained. and the initial terrain complexity of each topographic sub-area , calculate the difference between the two. If the difference is greater than 1, the topographic survey sub-area is considered to be the difference part, and the output is the land space planning change area.

[0027] (III) Beneficial effects The present invention provides a land space planning topographic survey system, which has the following beneficial effects: 1. By collecting historical topographic maps of the area to be measured, the area to be measured is evenly divided into topographic measurement sub-areas of equal area according to the historical topographic maps, the terrain complexity of each topographic measurement sub-area is calculated, and the measurement method of each topographic measurement sub-area is determined. By reasonably dividing the topographic measurement sub-areas and determining the measurement method according to the terrain complexity, it is possible to avoid wasting resources on unnecessary high-precision measurements, thereby reducing measurement costs.

[0028] 2. Collect environmental data of the topographic survey sub-area within the time when the lidar collects data, calculate the environmental error coefficient, and issue an environmental error warning. This can help you understand the environmental conditions of the survey area in real time, identify in advance the risk of measurement errors that may be caused by environmental factors, and provide early warning information to surveyors, so that they can adjust the measurement plan or take corresponding measures in time to avoid data distortion.

[0029] 3. Use a drone equipped with a laser radar to measure the terrain data of the topographic survey sub-area, build the first point cloud database, project the three-dimensional point cloud data in the first point cloud database onto a two-dimensional plane, and divide the two-dimensional plane into uniform point cloud grids with an area of ​​1 square meter, and calculate the complexity of each point cloud grid , mark the fine measurement area, conduct two terrain data measurements, analyze and form the second point cloud data, merge the second point cloud data into the first point cloud database according to the GPS coordinates to form a complete point cloud data, and conduct a second measurement on the marked fine measurement area to further improve the data accuracy of these areas, which helps to ensure the accuracy and reliability of the entire terrain data set.

[0030] 4. Generate a survey topographic map based on the complete point cloud data, compare the initial topographic map with the complete topographic map, identify the differences, and output them as the land space planning change area. It can accurately identify the changes in natural elements such as topography, landforms, and vegetation coverage, which helps to more accurately grasp the current status and development trends of the regional natural environment. Based on accurate terrain change information, the planning layout can be adjusted and optimized more reasonably. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a schematic diagram of the structure of a national land space planning topographic survey system. DETAILED DESCRIPTION

[0032] 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.

[0033] See also Figure 1 The present invention provides a land space planning topographic survey system, comprising: The acquisition area division module is used to collect historical topographic maps of the area to be measured, divide the area to be measured evenly into topographic measurement sub-areas of equal area based on the historical topographic maps, calculate the terrain complexity of each topographic measurement sub-area, and determine the measurement method of each topographic measurement sub-area.

[0034] The historical topographic map of the area to be measured is obtained by accessing online platforms and databases such as the National Geospatial Data Cloud and Tiandi Map as the initial topographic map. GIS software (such as ArcGIS, QGIS, etc.) or programming tools (such as Python combined with GeoPandas library) are used to divide the initial topographic map into grids of equal size. Each grid is a topographic measurement sub-area and is numbered sequentially.

[0035] Extracting the number of contour lines within a topographic survey sub-area using GIS software and the elevation value of each contour line , calculate the initial terrain complexity of each topographic survey sub-area :

[0036] in, a represents the sequential number of each topographic survey sub-area, It represents the maximum value of the contour elevation value in the same topographic measurement sub-area. Indicates the minimum value of the contour elevation within the same topographic measurement sub-area.

[0037] Based on the initial terrain complexity The topographic measurement sub-areas are sorted from large to small according to their size. The topographic measurement sub-areas in the first 30% are marked as complex terrain areas, and the lidar is set with a high sampling frequency for data collection. The bottom 30% are marked as simple terrain areas, and the lidar is set with a low sampling frequency for data collection. The remaining topographic measurement sub-areas are marked as regular terrain areas, and the lidar is set with a regular sampling frequency for data collection.

[0038] By collecting historical topographic maps of the area to be measured, the area to be measured is evenly divided into topographic measurement sub-areas of equal area according to the historical topographic maps, the terrain complexity of each topographic measurement sub-area is calculated, and the measurement method of each topographic measurement sub-area is determined. By reasonably dividing the topographic measurement sub-areas and determining the measurement method according to the terrain complexity, it is possible to avoid wasting resources on unnecessary high-precision measurements, thereby reducing measurement costs.

[0039] The measurement environment analysis module is used to collect environmental data of the topographic measurement sub-area within the laser radar data collection time, calculate the environmental error coefficient, and issue an environmental error warning.

[0040] Several detection points were randomly set up in the topographic measurement sub-area, and the light intensity of each detection point was detected by a light meter, the humidity sensor detected the humidity of each detection point, and the light scattering monitor measured the total suspended particulate matter concentration in the atmosphere. After sorting, the average light intensity of each topographic measurement sub-area was obtained. , average humidity and the average total suspended particulate matter concentration .

[0041] Get the average light intensity for each topographic sub-area , average humidity and the average total suspended particulate matter concentration , calculate the environmental error coefficient :

[0042] in, Indicates the light intensity threshold of the laser radar. represents the humidity threshold of the lidar, Indicates the total suspended particulate matter concentration threshold of the lidar.

[0043] The effect of light intensity on laser ranging accuracy is not linear. Within a certain range, the increase in light intensity may gradually reduce the ranging accuracy. However, when the light intensity exceeds a certain threshold, the ranging accuracy will drop sharply due to receiver saturation or other physical limitations. During the experiment, the light intensity was gradually increased and the changes in ranging accuracy were observed. When the ranging accuracy began to drop sharply, it can be considered that the light intensity at this time has exceeded the threshold of the laser rangefinder.

[0044] When the environmental error coefficient When it is greater than 0, it means that the external environment of the current topographic measurement sub-area has a great impact on the measurement accuracy of the laser rangefinder, and an environmental error warning is issued to the outside, prompting to find another time to measure the topographic measurement sub-area.

[0045] By collecting environmental data of the topographic survey sub-area within the time when the lidar collects data, calculating the environmental error coefficient, and issuing an environmental error warning, we can understand the environmental conditions of the survey area in real time, identify in advance the risk of measurement errors that may be caused by environmental factors, and provide early warning information to surveyors so that they can adjust the measurement plan or take corresponding measures in time to avoid data distortion.

[0046] The data acquisition module uses a drone equipped with a laser radar to measure the topographic data of the topographic survey sub-area, builds the first point cloud database, projects the three-dimensional point cloud data in the first point cloud database onto a two-dimensional plane, and divides the two-dimensional plane into uniform point cloud grids with an area of ​​1 square meter, and calculates the complexity of each point cloud grid. , mark the fine measurement area, conduct 2 terrain data measurements, analyze and form the second point cloud data, and merge the second point cloud data into the first point cloud database according to the GPS coordinates to form a complete point cloud data.

[0047] The laser radar sensor, IMU, GPS and other equipment are installed on the drone, and the drone is controlled to fly according to the preset route. During the flight, the laser radar continuously emits laser pulses to the ground and receives reflected signals, and records the emission time, reception time, reflection intensity of the laser pulses, and GPS and IMU data at each time. GPS provides the absolute position information of the laser radar, and the IMU records the angular attitude of the platform (including roll, pitch and yaw) to determine the precise direction of the laser radar.

[0048] The distance between the laser and the target is calculated by the emission time and reception time of the laser pulse. Combined with GPS and IMU data, each laser point is converted from the local coordinate system of the laser radar to the global coordinate system. The calculated three-dimensional coordinates (X, Y, Z) and reflection intensity information of each laser point are combined into point cloud data to build the first point cloud database.

[0049] Project the 3D point cloud data in the first point cloud database onto a 2D plane, divide the 2D plane into uniform point cloud grids with an area of ​​1 square meter, and after numbering, count the number of point clouds on each point cloud grid. .

[0050] Get the number of points on each point cloud grid , Environmental error coefficient of the point cloud grid corresponding to the topographic measurement sub-area and initial terrain complexity , calculate the complexity of each point cloud grid :

[0051] in, c Indicates the sequential number of point cloud grids in the same topographic survey sub-area.

[0052] When the complexity of each point cloud grid When the grid complexity is greater than 1.2 times the mean value, it means that the spatial complexity of the area corresponding to the current grid is high, and the data needs to be improved and the GPS position coordinates corresponding to the center point of the point cloud grid are output. The mean value of the grid complexity is the complexity of all point cloud grids in all terrain measurement sub-areas. The mean of .

[0053] All output GPS position coordinates are sorted out and marked as fine measurement areas. A drone equipped with a laser radar is used to measure the terrain data of the fine measurement area twice, and the second point cloud data is analyzed to form the second point cloud data. The second point cloud data is merged into the first point cloud database according to the GPS coordinates to form a complete point cloud data.

[0054] Use a drone equipped with a laser radar to measure the topographic data of the topographic survey sub-area, build the first point cloud database, project the three-dimensional point cloud data in the first point cloud database onto a two-dimensional plane, and divide the two-dimensional plane into uniform point cloud grids with an area of ​​1 square meter. Calculate the complexity of each point cloud grid , mark the fine measurement area, conduct two terrain data measurements, analyze and form the second point cloud data, merge the second point cloud data into the first point cloud database according to the GPS coordinates to form a complete point cloud data, and conduct a second measurement on the marked fine measurement area to further improve the data accuracy of these areas, which helps to ensure the accuracy and reliability of the entire terrain data set.

[0055] The terrain data analysis module generates a survey topographic map based on the complete point cloud data, compares the initial topographic map with the survey topographic map, identifies the differences, and outputs them as the changed areas of the national land space planning.

[0056] Use point cloud processing software (such as CloudCompare, GlobalMapper, Lidar360, etc.) to classify the complete point cloud data, distinguish different categories of point cloud data such as ground points, vegetation points, building points, etc., extract elevation information from the classified ground point cloud, generate a digital elevation model (DEM), and use terrain surface reconstruction algorithms (such as TIN, Grid, etc.) to convert DEM data into a terrain surface model that is easier to represent and analyze. Draw contour lines based on DEM data or terrain surface models and output measured topographic maps.

[0057] The initial topographic map is georeferenced with the survey topographic map to align them precisely in spatial position. Based on the division of the topographic survey sub-areas, the number of contour lines in the topographic survey sub-areas in the survey topographic map is extracted using GIS software. and the elevation value of each contour line , calculate the measurement terrain complexity of each topographic measurement sub-area in the measurement terrain map :

[0058] in, It indicates the maximum value of the contour elevation value in the same topographic measurement sub-area in the topographic map. It indicates the minimum value of the contour elevation value in the same topographic measurement sub-area in the topographic map.

[0059] Get the measured terrain complexity of each topographic survey sub-area in the measured terrain map and the initial terrain complexity of each topographic sub-area , calculate the difference between the two. If the difference is greater than 1, the topographic survey sub-area is considered to be the difference part, and the output is the land space planning change area.

[0060] Generate a survey topographic map based on the complete point cloud data, compare the initial topographic map with the complete topographic map, identify the differences, and output them as the land space planning change area. This can accurately identify the changes in natural elements such as topography, landforms, and vegetation coverage, which helps to more accurately grasp the current status and development trends of the regional natural environment. Based on accurate terrain change information, the planning layout can be adjusted and optimized more reasonably.

[0061] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented using software, the above embodiments may be implemented in whole or in part in the form of a computer program product. A person of ordinary skill in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented in electronic hardware, or in a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution.

[0062] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0063] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A land space planning topographic survey system, characterized by: include: The acquisition area division module is used to collect the historical topographic map of the area to be measured, divide the area to be measured evenly into topographic measurement sub-areas of equal area according to the historical topographic map, calculate the terrain complexity of each topographic measurement sub-area, and determine the measurement method of each topographic measurement sub-area; The measurement environment analysis module is used to collect environmental data of the topographic measurement sub-area within the laser radar data collection time, calculate the environmental error coefficient, and issue an environmental error warning; The data acquisition module uses a drone equipped with a laser radar to measure the topographic data of the topographic survey sub-area, builds the first point cloud database, projects the three-dimensional point cloud data in the first point cloud database onto a two-dimensional plane, and divides the two-dimensional plane into uniform point cloud grids with an area of ​​1 square meter, and calculates the complexity of each point cloud grid. , mark the fine measurement area, conduct two terrain data measurements, analyze and form the second point cloud data, and merge the second point cloud data into the first point cloud database according to the GPS coordinates to form a complete point cloud data; The terrain data analysis module generates a survey topographic map based on the complete point cloud data, compares the initial topographic map with the survey topographic map, identifies the differences, and outputs them as the changed areas of the national land space planning.

2. A land space planning topographic survey system according to claim 1, characterized in that: Extracting the number of contour lines within a topographic survey sub-area using GIS software and the elevation value of each contour line , calculate the initial terrain complexity of each topographic sub-area : in, a represents the sequential number of each topographic survey sub-area, It represents the maximum value of the contour elevation value in the same topographic measurement sub-area. Indicates the minimum value of the contour elevation within the same topographic measurement sub-area.

3. A land space planning topographic survey system according to claim 2, characterized in that: Based on the initial terrain complexity The topographic measurement sub-areas are sorted from large to small according to their size. The topographic measurement sub-areas in the first 30% are marked as complex terrain areas, and the lidar is set with a high sampling frequency for data collection. The bottom 30% are marked as simple terrain areas, and the lidar is set with a low sampling frequency for data collection. The remaining topographic measurement sub-areas are marked as regular terrain areas, and the lidar is set with a regular sampling frequency for data collection.

4. A land space planning topographic survey system according to claim 1, characterized in that: Several detection points are randomly set in the topographic measurement sub-area. The light intensity of each detection point is detected by a light meter, the humidity sensor is used to detect the humidity of each detection point, and the light scattering monitor is used to measure the total suspended particulate matter concentration in the atmosphere. After sorting, the average light intensity of each topographic measurement sub-area is obtained. , average humidity and the average total suspended particulate matter concentration .

5. A land space planning topographic survey system according to claim 4, characterized in that: Get the average light intensity for each topographic sub-area , average humidity and the average total suspended particulate matter concentration , calculate the environmental error coefficient : in, Represents the light intensity threshold of the laser radar. Indicates the humidity threshold of the lidar, Indicates the total suspended particulate matter concentration threshold of the lidar; When the environmental error coefficient When it is greater than 0, an environmental error warning is issued.

6. A land space planning topographic survey system according to claim 1, characterized in that: Project the 3D point cloud data in the first point cloud database onto a 2D plane, divide the 2D plane into uniform point cloud grids with an area of ​​1 square meter, and count the number of point clouds on each point cloud grid. .

7. A land space planning topographic survey system according to claim 6, characterized in that: Get the number of points on each point cloud grid , Environmental error coefficient of the point cloud grid corresponding to the topographic measurement sub-area and initial terrain complexity , calculate the complexity of each point cloud grid : in, c Indicates the sequential number of point cloud grids in the same topographic survey sub-area.

8. A land space planning topographic survey system according to claim 7, characterized in that: When the complexity of each point cloud grid When the grid complexity is greater than 1.2 times the mean value, the GPS position coordinates corresponding to the center point of the point cloud grid are output, where the mean value of the grid complexity is the complexity of all point cloud grids in all terrain measurement sub-areas. The mean of .

9. The land space planning topographic survey system according to claim 1, characterized in that: Geo-reference the initial topographic map with the survey topographic map and use GIS software to extract the number of contour lines within the topographic sub-area in the survey topographic map and the elevation value of each contour line , calculate the measurement terrain complexity of each topographic measurement sub-area in the measurement terrain map .

10. A land space planning topographic survey system according to claim 9, characterized in that: Get the measured terrain complexity of each topographic survey sub-area in the measured terrain map and the initial terrain complexity of each topographic sub-area , calculate the difference between the two. If the difference is greater than 1, the topographic survey sub-area is considered to be the difference part, and the output is the land space planning change area.

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