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CN-121982588-A - High-altitude area aerial shooting partition method and system based on gradient slope direction

CN121982588ACN 121982588 ACN121982588 ACN 121982588ACN-121982588-A

Abstract

The application discloses a high-altitude area aerial photography zoning method and system based on gradient slope direction. The method comprises the steps of calculating gradient and slope direction from a DEM grid by grid, dividing a map according to a map forming resolution ratio and extracting gradient slope statistical characteristics, carrying out eight-direction hierarchical clustering, carrying out iteration until the grade is stable, classifying adjacent maps meeting the conditions of characteristic difference and area proportion into the same area in a seed point expansion mode to form an initial gradient partition, sequentially carrying out similar characteristic combination, scattered isolated partition combination and single map combination to obtain a gradient homogeneous partition, replacing a gradient map repeated flow with a gradient map to obtain a gradient homogeneous partition, carrying out intersecting extraction of the gradient and slope direction uniform seed areas of the two types of partitions, merging other areas according to a characteristic difference minimum principle by taking the seed area as a core, and outputting the gradient combined aerial photography partition. The application carries out conventional front-view aerial photography on the inclined plane, reduces the aerial photography difficulty of the high-altitude area and improves the accuracy and efficiency of aerial photography measurement.

Inventors

  • LIU XIAOLONG

Assignees

  • 中测新图(北京)遥感技术有限责任公司

Dates

Publication Date
20260505
Application Date
20260123

Claims (10)

  1. 1. A method for aerial photography zoning of a high altitude area based on gradient slope direction, which is characterized by comprising the following steps: Calculating the gradient and the slope direction grid by grid based on a digital elevation model of the measuring area, dividing the measuring area into pictures according to the picture forming resolution, and extracting the statistical characteristics of the gradient and the slope direction of each picture; Carrying out directional hierarchical clustering on the slope directions of the pictures by taking the statistical characteristics of the slope and the slope directions as input, carrying out iteration until the levels are stable, carrying out neighborhood growth on the pictures by taking a stable level graph as constraint and adopting a seed point expansion mode, and classifying adjacent pictures with characteristic differences and area proportions meeting set conditions into the same area to form an initial slope direction partition; sequentially carrying out similar feature combination, scattered isolated partition combination and single-map combination on the initial slope partition to obtain a slope homogeneous partition, replacing the slope map with the slope map, and repeatedly executing map partitioning, clustering, seed expansion and combination processes to obtain the slope homogeneous partition; And (3) intersecting the slope homogenizing partition with the slope homogenizing partition in space, extracting a seed region with uniform slope and slope, merging other regions by taking the seed region as a core according to a principle of minimum characteristic difference, and obtaining the slope and slope combined aerial photography partition.
  2. 2. The method of claim 1, wherein calculating the grade and direction on a grid-by-grid basis based on the survey digital elevation model comprises: Calculating the elevation change value d x of the central grid in the x direction and the elevation change value d y of the central grid in the y direction by adopting a 3X 3 moving window according to the formula The slope angle a and the slope tangent S p are obtained, and the slope p d is obtained from p d =sqrt（d x *d x +d y *d y ).
  3. 3. The method of claim 1, wherein dividing the region into frames at a mapping resolution comprises: Dividing the measuring area into square image frames according to the ground resolution corresponding to the imaging scale, wherein the image frame length is correspondingly increased when the resolution is reduced, and the image frame length is correspondingly reduced when the resolution is increased.
  4. 4. The method of claim 1, wherein the direction hierarchical clustering comprises equally dividing the slope direction 0-360 DEG into eight directions and sequentially encoding, taking the average value of the slope direction of the graph as an initial level, iteratively calculating the centers of all levels and reclassifying the graph until the graph level is no longer changed or two continuous rounds of change are the same.
  5. 5. The method of claim 1, wherein the neighborhood growing is performed on the map by using a seed point expansion method, and the neighboring map with the characteristic difference and the area ratio meeting the set conditions is classified into the same area to form an initial slope partition, and the method specifically comprises: starting scanning from the lower left corner picture, taking the unlabeled picture as a seed, establishing a partition picture stack, and giving the range of the seed picture, the gradient and slope statistical characteristics of the seed picture to the current partition and stacking; retrieving the four-neighborhood image of the image in sequence, and if the difference between the maximum value and the minimum value of the characteristics of the neighborhood image and the current partition does not exceed the characteristic value difference limit, or if the exceeding limit is smaller than the area limit, classifying the neighborhood image into the current partition and stacking; completing a partition until the four neighborhood search is completed and no expansion is needed; Scanning the next unlabeled pattern as new seed is continued until all patterns fall into the corresponding partition.
  6. 6. The method of claim 1, wherein the similar feature merging comprises: And traversing all the initial slope partitions, merging the partitions which are adjacent to each other in space and have the statistical characteristic difference smaller than the characteristic value difference threshold value, and taking the merged statistical characteristic as a new region characteristic, and circulating until no adjacent partition meets the merging condition.
  7. 7. The method of claim 1, wherein the fragmented orphan partition merge comprises: Selecting partitions with smaller areas, searching partitions with the smallest statistical characteristic difference and the difference smaller than a twice characteristic value difference threshold value in adjacent partitions, merging, updating the characteristics of the new regions by the merged statistical characteristics, and circulating to all the fragmented partitions to finish merging.
  8. 8. A gradient slope direction-based high altitude area aerial photography zoning system, the system comprising: The extraction module is used for calculating the gradient and the slope direction grid by grid based on the digital elevation model of the measuring area, dividing the measuring area into pictures according to the picture forming resolution, and extracting the statistical characteristics of the gradient and the slope direction of each picture; The initial partitioning module is used for carrying out directional hierarchical clustering on the slope directions of the pictures by taking the slope and slope statistical characteristics as input, carrying out iteration until the levels are stable, carrying out neighborhood growth on the pictures by taking a stable level graph as constraint and adopting a seed point expansion mode, and classifying adjacent pictures with characteristic differences and area proportions meeting set conditions into the same area to form an initial slope partitioning; The merging module is used for sequentially carrying out similar feature merging, scattered isolated partition merging and single-map merging on the initial slope partition to obtain a slope homogeneous partition, replacing the slope map with the slope map, and repeatedly executing map partitioning, clustering, seed expansion and merging processes to obtain the slope homogeneous partition; and the output module is used for intersecting the slope homogeneous partition with the slope homogeneous partition in space, extracting a seed region with uniform slope and slope, merging other regions by taking the seed region as a core according to the principle of minimum characteristic difference, and obtaining the slope and slope combined aerial photography partition.
  9. 9. An electronic device comprising a memory and a processor, the memory storing a computer program that, when executed by the processor, performs the method of any of claims 1 to 7.
  10. 10. A computer readable storage medium, characterized in that a computer program is stored thereon, which computer program, when being executed by a processor, implements the method according to any of claims 1 to 7.

Description

High-altitude area aerial shooting partition method and system based on gradient slope direction Technical Field The application relates to the technical field of unmanned aerial vehicle aerial photography, in particular to a high-altitude area aerial photography zoning method and system based on gradient slope direction. Background The task design of aerial photogrammetry is an important component, and is directly related to the operation efficiency, the operation precision and the operation success rate of aerial photogrammetry operation. The task design of aerial photogrammetry is divided into two aspects of the zonal design of aerial photography areas and the aerial route laying design. Traditional photogrammetry adopts a mode of carrying out aerial photography subareas by adopting DEM data and then carrying out aerial photography, and the aerial photography operation has strong adaptability to flat areas, but has great influence on course overlapping degree and side overlapping degree of adjacent aerial images in areas with great elevation fluctuation of working areas such as mountain areas and the like. The unmanned aerial vehicle has the problems of small image, large image quantity, large image inclination angle, irregular inclination direction, irregular course overlapping degree and side overlapping degree and the like, and the problems bring certain difficulties to the internal processing such as image matching, aerial triangulation and the like, and the low base height ratio can lead to low elevation precision. In order to improve the elevation precision, the focal length of the camera needs to be reduced, so that the flying height is required to be relatively low, the flying height is low and is not suitable for the area with large height difference, and meanwhile, with the development of the oblique photography technology, the unmanned aerial vehicle oblique photography makes aerial photography subareas and aerial route design more difficult. The unmanned aerial vehicle aerial shooting partition method taking the spatial relationship and the flight safety into consideration provides an aerial shooting partition algorithm taking the spatial relationship and the flight safety into consideration, so that the fragmented partitions can be effectively combined, the flight safety is ensured, the number of the partitions is basically less than 2 per square kilometer, and the flight requirement of the unmanned aerial vehicle is met. The mountain mapping type low-altitude unmanned aerial vehicle route design and optimization research paper provides that a high-pixel and long-focal-length camera has better applicability to a large-fluctuation area. The design and realization paper of large scale aerial photography under the condition of large altitude difference topography provides principles and methods of photographic subareas and aerial route design, the determination of the datum plane of each subarea of aerial photography, the laying requirements of the aerial route, the determination method of various aerial photography factors, the quality requirements of aerial photography and the like, and the main technical parameters to be considered in the design are listed. Aerial photography partition method patent proposes aerial photography partition by using DEM elevation data, so that the elevation difference of the same partition is not more than 1/3 of the aerial altitude, and thus the consistency of resolution and aerial altitude can be ensured in the partition. The existing method basically utilizes DEM data to partition, is suitable for areas with less fluctuation, but is not suitable for areas with high altitude difference. Disclosure of Invention Based on the method and the system, the slope direction-based aerial photography zoning method and the system for the high-altitude area are provided, and the uniform direction and slope value of the terrain slope in the same zone are realized through the combined classification of slope direction and slope direction, seed expansion, similar merging and island merging, so that the geometrical consistency and stable matching characteristics of adjacent image imaging are ensured, and finally the precision, efficiency and flight safety of unmanned aerial photography measurement of complex mountain areas are improved. In a first aspect, a method for aerial photography zoning of a high altitude area based on gradient and slope is provided, the method comprising: Calculating the gradient and the slope direction grid by grid based on a digital elevation model of the measuring area, dividing the measuring area into pictures according to the picture forming resolution, and extracting the statistical characteristics of the gradient and the slope direction of each picture; Carrying out directional hierarchical clustering on the slope directions of the pictures by taking the statistical characteristics of the slope and the slope directions as input, carrying out ite