CN118154814A - Method for fitting light-weight terrain surface grid by using land three-dimensional point cloud and isopachous line - Google Patents
Method for fitting light-weight terrain surface grid by using land three-dimensional point cloud and isopachous line Download PDFInfo
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Abstract
The invention relates to the technical field of geological three-dimensional modeling, and discloses a method for fitting a lightweight terrain surface grid by using land three-dimensional point cloud and an isopachous line, which comprises the following steps: generating a land terrain surface irregular triangle grid according to the land three-dimensional point cloud, and carrying out light weight through a grid structure to obtain a light-weight first land terrain surface grid; preliminarily forming an underwater topography surface grid by using known isodepth lines, and extracting boundary lines; cutting the first land terrain surface grid according to the boundary line to obtain a second land terrain surface grid; generating a first contour line according to the second land terrain surface grid, and carrying out fusion analysis by combining the known contour lines to obtain a second contour line; and generating a light-weight land and water integrated terrain surface grid according to the second contour line. The land surface grid is light, the light land and water integrated land surface grid is obtained, the labor cost is saved, the engineering period is shortened, and high-precision land and water land data is provided for engineering survey and design.
Description
Technical Field
The invention relates to the technical field of geological three-dimensional modeling, in particular to a method for fitting a light-weight terrain surface grid by using land three-dimensional point clouds and isopachous lines.
Background
The data multisource polymorphism of the terrain surface grid is generated, and particularly when massive point cloud data generated by unmanned aerial vehicle oblique photography is subjected to high fitting with the isocenter, two main problems are faced: the terrain surface grid generated by overlarge point cloud data volume is rotationally stuck in software, so that the software is difficult to operate and cannot be used for three-dimensional geological modeling; the situation that a large number of grid space spread relations are mutually contradictory and fusion connection is unreasonable occurs at the junction of the terrain surface grid generated by the point cloud and the underwater terrain surface grid generated by the equal-depth line. Such a problem arises because: the unmanned aerial vehicle has high depicting precision when carrying out oblique photogrammetry on the ground, millions or even tens of millions of space position points are generated after three-dimensional calculation, and the situation that grid nodes are excessively redundant and the model body quantity is excessively large is generated when the unmanned aerial vehicle is directly used for generating the grid of the terrain; the point cloud data and the isocenter line data have larger differences in the acquisition instrument, the acquisition method, the acquisition precision, the acquisition standard, the acquisition period and the acquired data processing mode, so that the point cloud data and the isocenter line data are required to be manually analyzed and processed when the point cloud data and the isocenter line data are fused.
Currently, generating terrain meshes is typically generated using surface, subsurface contours and elevation points. Firstly, dispersing points on a contour line and forming a point set with elevation points; the set of points is then used to generate a terrain surface mesh using the TIN algorithm. In the prior art, the method for generating the terrain surface grid by using the contour lines cannot directly utilize three-dimensional point cloud data formed by unmanned aerial vehicle oblique photography, a great deal of internal industry processing analysis work is required for aerial survey professionals, a great deal of time is consumed for transmitting the contour lines to geological design professionals for use in a mapping result mode, a great deal of manpower, time and energy are input, and projects with short engineering survey design period are faced, so that professional collaborative parallel operation is difficult to realize, and project engineering period is difficult to guarantee. In addition, the generated contour line generally does not contain the contour line of the underwater topography, and the accuracy of the topography data provided for river management engineering is not high.
Therefore, a method for fitting a lightweight terrain surface grid by using land three-dimensional point clouds and equal depth lines is needed, the weight of the terrain surface grid can be reduced, the lightweight amphibious integrated terrain surface grid is obtained, the operation is simple and convenient, a large amount of labor cost is saved, the engineering period is shortened, and high-precision amphibious terrain data can be provided for engineering survey and design.
Disclosure of Invention
In order to solve the technical problems, the invention provides the method for fitting the light-weight terrain surface grid by using the land three-dimensional point cloud and the isopipe, which can realize the light-weight of the terrain surface grid, save a great deal of labor cost for processing the three-dimensional point cloud data and has simple and convenient operation.
The invention provides a method for fitting a lightweight terrain surface grid by using a land three-dimensional point cloud and an isopachous line, which comprises the following steps:
S1, generating land terrain surface irregular triangular grids according to land three-dimensional point clouds generated by unmanned aerial vehicle oblique photography, and carrying out light weight on the land terrain surface irregular triangular grids through a grid structure to obtain light-weight first land terrain surface grids;
s2, preliminarily forming an underwater topography grid by using known isodepth lines, and extracting boundary lines of the underwater topography grid;
S3, cutting the first land terrain surface grid according to the boundary line of the underwater land terrain surface grid to obtain a second land terrain surface grid;
S4, generating a first contour line according to the second land terrain surface grid, and carrying out fusion analysis on the first contour line and the known contour line to obtain a second contour line;
s5, generating a light amphibious integrated terrain surface grid according to the second contour line.
Further, S1, generating a land terrain surface irregular triangle mesh according to a land three-dimensional point cloud generated by unmanned aerial vehicle oblique photography, and performing light weight on the land terrain surface irregular triangle mesh through a grid mesh structure, where obtaining a light-weight first land terrain surface mesh includes:
s11, acquiring three-dimensional coordinates of all points in the land three-dimensional point cloud;
S12, generating an irregular triangular grid of the land terrain according to the three-dimensional coordinates of all points;
S13, carrying out light weight treatment on the irregular triangular meshes of the land terrain surface to obtain a light weight digital terrain model of a grid structure;
S14, converting the light-weight digital terrain model into a light-weight first land terrain surface grid.
Further, S13, when performing the light-weight processing on the irregular triangular mesh of the land terrain surface to obtain the light-weight digital terrain model of the mesh structure, further includes:
when the mapping precision is 1:500, the X spacing and the Y spacing of the grid structure of the digital terrain model are 2 meters;
When the mapping precision is 1:1000 or 1:2000, the X spacing and the Y spacing of the grid mesh structure of the digital terrain model are both 4 meters;
when the mapping precision is greater than 1:2000, the X spacing and the Y spacing of the grid mesh structure of the digital terrain model are both 8 meters or 16 meters.
Further, S3, cutting the first land terrain surface grid according to the boundary line of the underwater terrain surface grid, to obtain a second land terrain surface grid, including:
overlapping the boundary line of the underwater topography surface grid with the first land topography surface grid, cutting the first land topography surface grid, and cutting off a grid area in the boundary line range of the underwater topography surface grid in the first land topography surface grid to obtain a second land topography surface grid.
Further, the first land terrain surface grid is trimmed using boolean operations.
Further, in S4, when generating the first contour line according to the second land terrain surface grid, the method further includes:
when the mapping precision is 1:500, the distance between the first contour lines is 1 meter;
when the mapping precision is 1:1000 or 1:2000, the distance between the first contour lines is 2 meters;
when the mapping accuracy is greater than 1:2000, the distance between the first contour lines is 4 meters or 8 meters.
Further, S4, generating a first contour line according to the second land terrain surface grid, and performing fusion analysis on the first contour line and the known contour line to obtain a second contour line, where the obtaining includes:
s41, generating a first contour line according to a second land terrain surface grid, comparing the mapping precision of the first contour line with the mapping precision of a known contour line, and taking the mapping precision of the first contour line and the mapping precision of the known contour line, which are higher in mapping precision, as a reference precision;
S42, carrying out fusion analysis on the first contour line and the known contour line, and adjusting the first contour line or the known contour line according to the reference precision;
The method specifically comprises the following steps:
S421, judging whether the line in the known contour line and the line in the first contour line intersect at the same point at the water edge line or not when the mapping precision of the first contour line is used as the reference precision; wherein, the water boundary is the boundary between the water body and the land;
if the lines do not intersect at the same point, manually adjusting the intersection of the lines in the known contour line and the corresponding lines in the first contour line to the same point, and carrying out linear encryption on the known contour line to ensure that the precision of the known contour line is consistent with that of the first contour line; if the two equal-depth lines intersect at the same point, the known equal-depth lines are directly subjected to linear encryption, so that the precision of the known equal-depth lines is consistent with the precision of the first equal-depth lines;
S422, judging whether the line in the first contour line and the line in the known contour line intersect at the same point at the water edge line or not when the mapping precision of the known contour line is used as the reference precision;
If the lines do not intersect at the same point, manually adjusting the line in the first contour line and the corresponding line in the known contour line to intersect at the same point, and carrying out linear encryption on the first contour line to ensure that the precision of the first contour line is consistent with that of the known contour line; if the first contour lines intersect at the same point, the first contour lines are directly subjected to linear encryption, so that the precision of the first contour lines is consistent with the precision of the known contour lines;
S43, superposing the adjusted first contour line and the known contour line to obtain a second contour line.
Further, the mapping accuracy is determined according to the project requirements, the stage in which the project is located and the type of the mapping region.
The invention also provides a system for fitting the lightweight terrain surface grid by using the land three-dimensional point cloud and the equal-depth line, which is used for executing the method for fitting the lightweight terrain surface grid by using the land three-dimensional point cloud and the equal-depth line, and comprises the following modules:
the light-weight processing module is used for generating a land terrain surface irregular triangular grid according to the land three-dimensional point cloud generated by unmanned aerial vehicle oblique photography, and carrying out light weight on the land terrain surface irregular triangular grid through a grid structure to obtain a light-weight first land terrain surface grid;
The boundary line extraction module is used for preliminarily forming an underwater topography grid by using known contour lines and extracting boundary lines of the underwater topography grid;
the cutting module is connected with the lightweight processing module and the boundary line extraction module and is used for cutting the first land terrain surface grid to obtain a second land terrain surface grid;
the contour line generation module is connected with the cutting module and is used for generating a first contour line according to the second land terrain surface grid, and carrying out fusion analysis on the first contour line and the known contour line to obtain a second contour line;
and the terrain surface grid generating module is connected with the contour line generating module and is used for generating the light-weight amphibious integrated terrain surface grid according to the second contour line.
The embodiment of the invention has the following technical effects:
The three-dimensional point cloud data acquired by unmanned aerial vehicle oblique photography is subjected to light weight processing through a grid mesh structure, a light-weighted first land terrain surface grid is obtained, fusion analysis is carried out according to the first land terrain surface grid and the underwater terrain surface grid, mapping precision of a first contour line and a known contour line is adjusted, a second contour line of a water-land body is obtained, and a light-weighted water conservancy integrated terrain surface grid is generated according to the second contour line.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for fitting a lightweight terrain surface grid with a land three-dimensional point cloud and an isopipe;
FIG. 2 is a schematic diagram of a known contour adjustment according to a reference accuracy provided by an embodiment of the present invention;
FIG. 3 is a schematic view of a lightweight terrain surface mesh generated by a method for fitting a lightweight terrain surface mesh with a land three-dimensional point cloud and an isopipe, according to an embodiment of the present invention;
Fig. 4 is a schematic structural diagram of a system for fitting a lightweight terrain surface grid with a land three-dimensional point cloud and an isopipe, according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the invention, are within the scope of the invention.
Fig. 1 is a flowchart of a method for fitting a lightweight terrain surface grid with a land three-dimensional point cloud and an isopipe, according to an embodiment of the present invention, referring to fig. 1, specifically including:
S1, generating a land terrain surface irregular triangular grid according to land three-dimensional point cloud generated by unmanned aerial vehicle oblique photography, and carrying out light weight on the land terrain surface irregular triangular grid through a grid structure to obtain a light-weight first land terrain surface grid.
S11, acquiring three-dimensional coordinates of all points in the land three-dimensional point cloud.
For example, a terrestrial three-dimensional point cloud file in the. Las format may be imported into the microstate software and a file in the. Xyz format may be exported, where the terrestrial three-dimensional point cloud file in the. Xyz format includes xyz coordinates of all points and coloring information of each point, and other information unrelated to the three-dimensional coordinates, so that the terrestrial three-dimensional point cloud file in the. Xyz format may need to be further processed. And importing the land three-dimensional point cloud file in the xyz format into Geopak software to generate the land three-dimensional point cloud file in the dat format, wherein only the xyz coordinate information of all points reserved by the land three-dimensional point cloud file in the dat format is deleted, the information irrelevant to the three-dimensional coordinates is eliminated, the preliminary data weight reduction is realized, and the subsequent generation of a terrain surface grid according to the three-dimensional coordinate information of the land three-dimensional point cloud is facilitated.
S12, generating an irregular triangular grid of the land terrain according to the three-dimensional coordinates of all the points.
For example, a land three-dimensional point cloud file in the dat format may be used to generate a land terrain surface irregular triangular mesh in Geopak software, where the land terrain surface irregular triangular mesh is in the tin format. Because the node data of the irregular triangular mesh of the land terrain in the format is up to millions, which occupies hundreds of megabytes in the memory of the computer, the editing operation of the irregular triangular mesh of the land terrain in the format is difficult and time-consuming, and the irregular triangular mesh of the land terrain in the format needs to be further light-weighted.
S13, carrying out light weight treatment on the irregular triangular meshes of the land terrain surface to obtain a light weight digital terrain model of the grid mesh structure.
Illustratively, the entire Grid surface of the land terrain surface irregular triangle Grid in the. Tin format may be subjected to a light-weight operation in Geopak software, and converted into a light-weight digital terrain Model (DIGITAL TERRAIN Model, DTM) of a Grid mesh structure, which is in the. Lat format. At this time, the node number of the lightweight digital terrain model of the grid structure is generally reduced to less than one tenth of the node number of the irregular triangular grid of the land terrain surface, and the lightweight effect is obvious because the node number occupies less than 10 megabytes of the computer memory.
Specifically, when the mapping accuracy is 1:500, the X spacing and the Y spacing of the grid structure of the digital terrain model are both 2 meters.
When the mapping precision is 1:1000 or 1:2000, the X spacing and the Y spacing of the grid mesh structure of the digital terrain model are both 4 meters.
When the mapping precision is greater than 1:2000, the X spacing and the Y spacing of the grid mesh structure of the digital terrain model are both 8 meters or 16 meters.
According to the corresponding relation between the mapping precision and the X spacing and the Y spacing of the grid mesh structure of the digital terrain model, the requirement of the mapping precision can be better met on the basis of meeting the light weight, and the situation that the morphology of the terrain surface grid is distorted, such as the disappearance of the terrain fluctuation or the incomplete display, is avoided.
Further, the mapping precision can be determined according to the project requirement, the stage of the project and the type of the mapping region; the project requirements can include actual requirements of the project on the mapping precision or standard standards in the project, the project stage can include an initial stage, a lapping stage, a construction stage and the like, different mapping precision requirements can be met according to different stages, the requirements on the mapping precision can be higher and higher along with the gradual progress of the engineering stage, the type of the mapping region can include a building region and a non-building region, and the requirements of the building region on the mapping precision are generally higher than those of the non-building region.
S14, converting the light-weight digital terrain model into a light-weight first land terrain surface grid.
For example, a lightweight digital terrain model in the lat format may be converted in MapStation software into a lightweight first land terrain surface grid.
S2, preliminarily forming an underwater topography grid by using known isodepth lines, and extracting boundary lines of the underwater topography grid.
For example, the underwater topography grid can be directly formed according to known equal depth lines in a 'water conservancy and hydropower engineering three-dimensional geological survey system' developed by a northern company in China, and then boundary lines of the underwater topography grid can be extracted through extracting boundary functions according to MicroStation software.
S3, cutting the first land terrain surface grid according to the boundary line of the underwater terrain surface grid to obtain a second land terrain surface grid.
Specifically, the boundary line of the underwater topography surface grid is overlapped with the first land topography surface grid, the first land topography surface grid is cut, and a grid area in the boundary line range of the underwater topography surface grid in the first land topography surface grid is cut off, so that a second land topography surface grid is obtained.
Further, the cutting processing of the first land terrain surface grid according to the boundary line of the underwater land terrain surface grid is a process of cutting the grid surface by utilizing the boundary line, and the Boolean operation can perform any addition and subtraction operation on two or more graphs, so that the cutting processing of the first land terrain surface grid is realized by utilizing the Boolean operation in the scheme.
S4, generating a first contour line according to the second land terrain surface grid, and carrying out fusion analysis on the first contour line and the known contour line to obtain a second contour line.
S41, generating a first contour line according to the second land terrain surface grid, comparing the mapping precision of the first contour line with the mapping precision of the known contour line, and taking the mapping precision of the first contour line and the mapping precision of the known contour line, which are higher in mapping precision, as a reference precision.
For example, the contour line function can be generated through the terrain surface in the 'water conservancy and hydropower engineering three-dimensional geological survey system' developed by the northern company of Zhongshui, or other three-dimensional geological modeling software capable of realizing the function, and the first contour line is generated according to the second land terrain surface grid.
S42, performing fusion analysis on the first contour line and the known contour line, and adjusting the first contour line or the known contour line according to the reference precision.
Specifically, because the mapping precision of the first contour line and the known contour line are different, when the first contour line and the known contour line are fused, there is a possibility that obvious abnormality exists, the precision of the first contour line and the known contour line needs to be adjusted to be consistent, and the first contour line and the known contour line are manually adjusted according to experience. The mapping precision of the higher mapping precision of the two is used as the reference precision to adjust the lower mapping precision, so that the precision of the land and water integrated topographic data is improved.
S421, judging whether the line in the known contour line and the line in the first contour line intersect at the same point at the water edge line or not when the mapping precision of the first contour line is taken as the reference precision.
Specifically, if the lines do not intersect at the same point, manually adjusting the intersection of the lines in the known contour line and the corresponding lines in the first contour line to the same point, and carrying out linear encryption on the known contour line to ensure that the precision of the known contour line is consistent with that of the first contour line; if the two equal-depth lines intersect at the same point, the known equal-depth lines are directly subjected to linear encryption, so that the accuracy of the known equal-depth lines is consistent with that of the first equal-depth lines. The water boundary line is the boundary line between the water body and the land, and can be obtained through field investigation.
Specifically, taking the mapping precision of the first contour line as the reference precision as an example, fig. 2 is a schematic diagram of adjusting the known contour line according to the reference precision, and referring to fig. 2, the mapping precision of the first contour line is compared with the mapping precision of the known contour line, and the mapping precision of the first contour line is higher, so that the mapping precision of the first contour line is taken as the reference precision to adjust the known contour line. As can be seen from the figure, the line in the known contour line and the line in the first contour line fail to intersect at the same point at the water edge line, and at this time, the known contour line needs to be adjusted manually and empirically so that the two ends of the line in the known contour line intersect at the same point with the line in the corresponding first contour line. Further, the known isodepth line is linearly encrypted by a linear interpolation method. Illustratively, assuming that the distance between the known contours is 4 meters and the distance between the first contours is 2 meters, the contours of the 102 meter altitude can be linearly interpolated from the known contours of the 100 meter altitude and the known contours of the 104 meter altitude, and the known contours are encrypted so that the accuracy of the known contours is consistent with the accuracy of the first contours.
S422, when the mapping precision of the known contour line is taken as the reference precision, judging whether the line in the first contour line and the line in the known contour line intersect at the same point at the water edge line.
Specifically, if the lines do not intersect at the same point, manually adjusting the line in the first contour line to intersect with the corresponding line in the known contour line at the same point, and carrying out linear encryption on the first contour line to ensure that the precision of the first contour line is consistent with that of the known contour line; if the first contour lines intersect at the same point, linear encryption is directly carried out on the first contour lines, so that the precision of the first contour lines is consistent with the precision of the known contour lines.
S43, superposing the adjusted first contour line and the known contour line to obtain a second contour line.
Specifically, the second contour line at this time not only comprises a land contour line, but also comprises an underwater contour line, and can provide high-precision topographic data for geological design or river management.
Further, when the mapping accuracy is 1:500, the distance between the first contour lines is 1 meter.
When the mapping precision is 1:1000 or 1:2000, the distance between the first contour lines is 2 meters.
When the mapping accuracy is greater than 1:2000, the distance between the first contour lines is 4 meters or 8 meters.
According to the corresponding relation between the mapping precision and the distance between the first contour lines, the requirement of the mapping precision can be better met on the basis of meeting the light weight, and the situation that the morphology of the grid on the terrain surface is distorted, such as the disappearance of the fluctuation of the terrain or incomplete display, is avoided. The mapping precision is determined according to the project requirement, the stage where the project is located and the type of the mapping region.
S5, generating a light amphibious integrated terrain surface grid according to the second contour line.
Illustratively, fig. 3 is a schematic diagram of a lightweight terrain surface grid generated by using a method for fitting a land three-dimensional point cloud and an isopipe to the lightweight terrain surface grid, and referring to fig. 3, a lightweight amphibious integrated terrain surface grid may be generated in MapStation software according to a second contour line by a terrain surface generating function, where the amphibious integrated terrain surface grid includes not only a land terrain surface grid but also an underwater terrain surface grid.
According to the embodiment of the invention, three-dimensional point cloud data acquired by unmanned aerial vehicle oblique photography is subjected to light weight treatment through a grid mesh structure, so that a light-weight first land terrain surface grid is obtained, fusion analysis is carried out according to the first land terrain surface grid and an underwater land surface grid, mapping precision of a first contour line and a known contour line is adjusted, a water-land integrated second contour line is obtained, and a light-weight water conservancy integrated land surface grid is generated according to the second contour line.
Fig. 4 is a schematic structural diagram of a system for fitting a lightweight terrain surface grid with a land three-dimensional point cloud and an isopipe, according to an embodiment of the present invention, where the system is used for executing a method for fitting a lightweight terrain surface grid with a land three-dimensional point cloud and an isopipe according to the above embodiment, and as shown in fig. 4, the system includes the following modules:
the light-weight processing module is used for generating a land terrain surface irregular triangular grid according to the land three-dimensional point cloud generated by unmanned aerial vehicle oblique photography, and carrying out light weight on the land terrain surface irregular triangular grid through a grid structure to obtain a light-weight first land terrain surface grid;
The boundary line extraction module is used for preliminarily forming an underwater topography grid by using known contour lines and extracting boundary lines of the underwater topography grid;
the cutting module is connected with the lightweight processing module and the boundary line extraction module and is used for cutting the first land terrain surface grid to obtain a second land terrain surface grid;
the contour line generation module is connected with the cutting module and is used for generating a first contour line according to the second land terrain surface grid, and carrying out fusion analysis on the first contour line and the known contour line to obtain a second contour line;
and the terrain surface grid generating module is connected with the contour line generating module and is used for generating the light-weight amphibious integrated terrain surface grid according to the second contour line.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present application. As used in this specification, the terms "a," "an," "the," and/or "the" are not intended to be limiting, but rather are to be construed as covering the singular and the plural, unless the context clearly dictates otherwise. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method or apparatus that includes the element.
It should also be noted that the positional or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the positional or positional relationship shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or element in question must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. Unless specifically stated or limited otherwise, the terms "mounted," "connected," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.
Claims (9)
1. The method for fitting the light terrain surface grid by using the land three-dimensional point cloud and the isopachous line is characterized by comprising the following steps of:
S1, generating a land terrain surface irregular triangular grid according to land three-dimensional point cloud generated by unmanned aerial vehicle oblique photography, and carrying out light weight on the land terrain surface irregular triangular grid through a grid structure to obtain a light-weight first land terrain surface grid;
S2, preliminarily forming an underwater topography grid by using known isodepth lines, and extracting boundary lines of the underwater topography grid;
S3, cutting the first land terrain surface grid according to the boundary line of the underwater terrain surface grid to obtain a second land terrain surface grid;
S4, generating a first contour line according to the second land terrain surface grid, and carrying out fusion analysis on the first contour line and the known contour line to obtain a second contour line;
s5, generating a light-weight land and water integrated terrain surface grid according to the second contour line.
2. The method for fitting a lightweight terrain mesh with a land three-dimensional point cloud and an isopipe of claim 1, wherein the step S1 of generating a land terrain irregular triangular mesh from the land three-dimensional point cloud generated by unmanned aerial vehicle oblique photography and lightening the land terrain irregular triangular mesh with a mesh structure, the method comprising:
s11, acquiring three-dimensional coordinates of all points in the land three-dimensional point cloud;
S12, generating an irregular triangular grid of the land terrain according to the three-dimensional coordinates of all points;
S13, carrying out light weight treatment on the irregular triangular grid of the land terrain surface to obtain a light weight digital terrain model of a grid structure;
S14, converting the light-weight digital terrain model into a light-weight first land terrain surface grid.
3. The method for fitting a lightweight terrain surface grid with a land three-dimensional point cloud and an isopipe according to claim 2, wherein the step S13, when performing a lightweight process on the land terrain irregular triangle grid, further comprises:
when the mapping precision is 1:500, the X spacing and the Y spacing of the grid structure of the digital terrain model are 2 meters;
When the mapping precision is 1:1000 or 1:2000, the X spacing and the Y spacing of the grid mesh structure of the digital terrain model are both 4 meters;
when the mapping precision is greater than 1:2000, the X spacing and the Y spacing of the grid mesh structure of the digital terrain model are both 8 meters or 16 meters.
4. The method for fitting a lightweight terrain surface grid with a three-dimensional point cloud and an isopipe of claim 1, wherein the step S3 of clipping the first land terrain surface grid according to the boundary line of the underwater terrain surface grid to obtain a second land terrain surface grid comprises:
overlapping the boundary line of the underwater topography surface grid with the first land topography surface grid, cutting the first land topography surface grid, and cutting off a grid area in the boundary line range of the underwater topography surface grid in the first land topography surface grid to obtain a second land topography surface grid.
5. The method for fitting a lightweight terrain surface mesh with a land three-dimensional point cloud and an isopipe of claim 4, wherein the first land terrain surface mesh is trimmed using boolean operations.
6. The method for fitting a lightweight terrain surface grid using a terrestrial three-dimensional point cloud and an isodepth line according to claim 1, wherein in S4, when generating a first contour line from the second terrestrial terrain surface grid, further comprises:
when the mapping precision is 1:500, the distance between the first contour lines is 1 meter;
when the mapping precision is 1:1000 or 1:2000, the distance between the first contour lines is 2 meters;
when the mapping accuracy is greater than 1:2000, the distance between the first contour lines is 4 meters or 8 meters.
7. The method for fitting a lightweight terrain surface grid using a terrestrial three-dimensional point cloud and a contour line according to claim 6, wherein the step S4 of generating a first contour line from the second terrestrial terrain surface grid and performing fusion analysis on the first contour line and the known contour line to obtain a second contour line comprises:
S41, generating a first contour line according to the second land terrain surface grid, comparing the mapping precision of the first contour line and the known contour line, and taking the mapping precision of the one with higher mapping precision as a reference precision;
S42, carrying out fusion analysis on the first contour line and the known contour line, and adjusting the first contour line or the known contour line according to reference precision;
The method specifically comprises the following steps:
S421, judging whether the line in the known contour line and the line in the first contour line intersect at the same point at a water edge line or not when the mapping precision of the first contour line is used as reference precision; wherein, the water boundary is the boundary between the water body and the land;
If the known contour lines do not intersect at the same point, manually adjusting the intersection of the lines in the known contour lines and the corresponding lines in the first contour lines to intersect at the same point, and carrying out linear encryption on the known contour lines to ensure that the precision of the known contour lines is consistent with that of the first contour lines; if the known contour lines intersect at the same point, directly carrying out linear encryption on the known contour lines, so that the precision of the known contour lines is consistent with the precision of the first contour lines;
S422, judging whether the line in the first contour line and the line in the known contour line intersect at the same point at the water edge line or not when the mapping precision of the known contour line is used as reference precision;
If the first contour line does not intersect at the same point, manually adjusting the intersection of the line in the first contour line and the line in the corresponding known contour line at the same point, and carrying out linear encryption on the first contour line to ensure that the precision of the first contour line is consistent with the precision of the known contour line; if the first contour lines intersect at the same point, the first contour lines are directly subjected to linear encryption, so that the precision of the first contour lines is consistent with the precision of the known contour lines;
S43, superposing the adjusted first contour line and the known contour line to obtain a second contour line.
8. The method of fitting a lightweight terrain surface grid using a terrestrial three-dimensional point cloud to an isopipe of any of claims 3 or 6, wherein the mapping accuracy is determined based on project requirements, stage of project and type of mapping area.
9. A system for fitting a lightweight terrain surface grid with a land three-dimensional point cloud and an isopipe, for use in performing the method of fitting a lightweight terrain surface grid with a land three-dimensional point cloud and an isopipe of any one of claims 1-8, comprising the following modules:
the light-weight processing module is used for generating a land terrain surface irregular triangular grid according to the land three-dimensional point cloud generated by unmanned aerial vehicle oblique photography, and carrying out light weight on the land terrain surface irregular triangular grid through a grid structure to obtain a light-weight first land terrain surface grid;
The boundary line extraction module is used for preliminarily forming an underwater topography grid by using known contour lines and extracting boundary lines of the underwater topography grid;
The cutting module is connected with the light-weight processing module and the boundary line extraction module and is used for cutting the first land terrain surface grid to obtain a second land terrain surface grid;
The contour line generation module is connected with the cutting module and is used for generating a first contour line according to the second land terrain surface grid, and carrying out fusion analysis on the first contour line and the known contour line to obtain a second contour line;
And the terrain surface grid generating module is connected with the contour line generating module and is used for generating a light-weight land and water integrated terrain surface grid according to the second contour line.
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| CN103456041A (en) * | 2013-08-28 | 2013-12-18 | 中国人民解放军海军大连舰艇学院 | Three-dimensional terrain and radar terrain generating method based on S-57 electronic chart data |
| US20170365094A1 (en) * | 2016-04-04 | 2017-12-21 | University Of Cincinnati | Localized Contour Tree Method for Deriving Geometric and Topological Properties of Complex Surface Depressions Based on High Resolution Topographical Data |
| CN114170393A (en) * | 2021-11-30 | 2022-03-11 | 上海埃威航空电子有限公司 | Three-dimensional map scene construction method based on multiple data |
| WO2024074595A1 (en) * | 2022-10-05 | 2024-04-11 | Swiss Reinsurance Company Ltd. | Drone-based, airborne sensory system for flood elevation and flood occurrence probability measurements and return periods by proxy measurements and method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103456041A (en) * | 2013-08-28 | 2013-12-18 | 中国人民解放军海军大连舰艇学院 | Three-dimensional terrain and radar terrain generating method based on S-57 electronic chart data |
| US20170365094A1 (en) * | 2016-04-04 | 2017-12-21 | University Of Cincinnati | Localized Contour Tree Method for Deriving Geometric and Topological Properties of Complex Surface Depressions Based on High Resolution Topographical Data |
| CN114170393A (en) * | 2021-11-30 | 2022-03-11 | 上海埃威航空电子有限公司 | Three-dimensional map scene construction method based on multiple data |
| WO2024074595A1 (en) * | 2022-10-05 | 2024-04-11 | Swiss Reinsurance Company Ltd. | Drone-based, airborne sensory system for flood elevation and flood occurrence probability measurements and return periods by proxy measurements and method thereof |
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