A method for constructing a three-dimensional building model

Abstract

The present application relates to a method for constructing a three-dimensional building model, the method comprising: dividing the current area into a grid area composed of a plurality of grids, and determining the outer expansion area of ​​the grid area; dividing the grids of the grid area into a first grid and a second grid according to whether they are adjacent to the outer expansion area; performing flight photography along each of the grids in turn to obtain image data, and after each of the first grids is completed, continuing to perform flight photography along the outer expansion area adjacent to the current first grid; and processing the image data. Its beneficial effect is that the present application reduces the flight outer expansion area and improves the acquisition efficiency by performing outer expansion aerial photography of the grid area.

Description

Technical Field

[0001] The present application relates to the field of aerial survey technology, and more specifically, to a method for constructing a three-dimensional building model. Background Art

[0002] In the existing technology, in the central area of ​​the city, when planning the route according to the flight grid range, in order to ensure the integrity of the 3D data model, it is necessary to conduct flight collection for each grid expansion. Affected by data accuracy requirements and factors such as battery, and the need to expand 180 meters around, the UAV 3D data collection flight speed is slow and the collection efficiency is low, with an effective collection area of ​​1 square kilometer per day. Summary of the invention

[0003] In order to overcome the problems of slow flight speed and low collection efficiency of drone three-dimensional data collection in the prior art, the present application provides a three-dimensional building model construction method.

[0004] A method for constructing a three-dimensional building model, the method comprising:

[0005] Divide the current area into a grid area consisting of a plurality of grids, and determine an outer expansion area of ​​the grid area;

[0006] Divide the grid of the grid area into a first grid and a second grid according to whether it is adjacent to the outer expansion area;

[0007] Performing flight photography along each of the grids in turn to acquire image data, and after the flight of each of the first grids is completed, continuing to perform flight photography along the outer expansion area adjacent to the current first grid;

[0008] The image data is processed.

[0009] Optionally, before dividing the current area into a grid area consisting of a plurality of grids, the method further includes:

[0010] Determine whether there is a signal in the current area;

[0011] If yes, no processing is performed; otherwise, communication is performed through carrier phase differential technology;

[0012] Among them, the communication through carrier phase difference technology includes: setting the base station in a signal area and adjusting the radio power according to the distance from the current area, setting the mobile station on the collection device and setting the power of the mobile station to the same as the base station, and calculating the coordinates of the mobile station by receiving the coordinate signal of the base station.

[0013] Optionally, adjusting the radio station power according to the distance from the current area includes:

[0014] If the straight-line distance between the current area and the base station setting point exceeds 3km, the base station needs to use an external radio to enhance the signal frequency. If the straight-line distance between the current area and the base station setting point is within 3km, the base station's built-in radio is used for signal transmission.

[0015] Optionally, dividing the current area into a grid area consisting of a plurality of grids, and performing aerial photography along the grid lines of each grid in sequence, includes:

[0016] The current area is divided into multiple grid areas according to the flight altitude and distance, image photography range, and flight time of the acquisition equipment.

[0017] Optionally, the determining the outer expansion area of ​​the grid area includes:

[0018] Determine an outward flight line at the periphery of the grid area,

[0019] The area enclosed by the outward-expanding flight lines is larger than the area of ​​the grid area.

[0020] Optionally, the processing the image data includes:

[0021] Logically stitch multiple image data together through block merging technology;

[0022] Performing individual grid filtering in each of the grids to allow data between adjacent grids to be mutually usable;

[0023] The image data are all photo sets collected by multiple collection devices.

[0024] Optionally, the logically splicing of the plurality of image data by using the block merging technology includes:

[0025] The numbers, POS data and camera parameters of all photos in the grid are recorded in an XML file;

[0026] Merge XML files from multiple grids.

[0027] Optionally, performing individual grid filtering in each of the grids to make data between adjacent grids interoperable includes:

[0028] According to the XML file after the blocks are merged, when extracting photos from one of the grids, data of other grids around this grid are automatically extracted.

[0029] Optionally, the method further includes performing three-dimensional data modeling according to the image data, including:

[0030] According to the image data, each of the grids is subjected to spatial triangulation processing to generate an aerial triangulation result;

[0031] Import all the aerial triangulation results into the modeling system in sequence, point the engine of the task sequence of the aerial triangulation results to the same path, and then submit them for modeling in sequence.

[0032] Optionally, performing spatial triangulation processing on each of the grids to generate an aerial triangulation result includes:

[0033] Spatial triangulation generates triangulation results based on grid photos, POS values, camera parameters, photo control points and connection points through any of the following methods: simulation method, analytical method, flight strip method, independent model method, and ray bundle method.

[0034] Compared with the prior art, the beneficial effects of the present application are as follows: the present application reduces the outward expansion area of ​​the flight and improves the collection efficiency by performing outward expansion aerial photography of the grid area; and solves the problem that image control points cannot be deployed in areas with no signal; at the same time, it realizes the automatic sorting and production of three-dimensional data modeling tasks, improves the production efficiency and accuracy of three-dimensional building models, and reduces production costs and difficulties. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a flowchart of a method according to an embodiment of the present invention.

[0036] Figure 2 A schematic diagram of a grid area and an expanded area of ​​a method according to an embodiment of the present application. DETAILED DESCRIPTION

[0037] The present application is further described below in conjunction with specific implementation methods.

[0038] The same or similar numbers in the drawings of the embodiments of the present application correspond to the same or similar parts; in the description of the present application, it should be understood that if the terms "upper", "lower", "left", "right", "top", "bottom", "inside", "outside", etc. indicate the orientation or position relationship, it is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent.

[0039] In addition, if there are terms such as "first" and "second", they are only used for descriptive purposes, mainly to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components, and cannot be understood as indicating or implying relative importance.

[0040] In such Figure 1-2In the illustrated embodiment, the present application provides a method for constructing a three-dimensional building model, the method comprising:

[0041] 100, divide the current area into a grid area consisting of a plurality of grids, and determine the outer expansion area of ​​the grid area; In step 100, the current area is divided into a plurality of grid areas according to the flight altitude and distance, image shooting range, and flight time of the acquisition device.

[0042] 200, dividing the grids in the grid area into a first grid and a second grid according to whether they are adjacent to the external expansion area; In step 200, the present application determines the first grid and the second grid according to whether the grids in the grid area are adjacent to or connected to the external expansion area, the first grid being the grid outside the grid area connected to the external expansion area, and the second grid being the area inside the grid area that is not connected to the external expansion area.

[0043] 300, perform flight photography along each grid in turn to acquire image data, and after the flight of each of the first grids is completed, continue to perform flight photography along the outer expansion area adjacent to the current first grid; in step 300, in this step, the acquisition device performs flight acquisition along each grid in turn. When flying in the first grid, after the flight of the first grid is completed, continue to fly along the adjacent outer expansion area. When flying in the second grid, just fly along the grid lines of the second grid. 400, process the image data. In step 400, the image data is processed, including: logically splicing multiple image data through block merging technology; performing separate grid filtering in each grid to make data between adjacent grids interchangeable; wherein the image data are all photo sets collected by multiple acquisition devices.

[0044] This application reduces the outward expansion area of ​​the flight and improves the collection efficiency by performing outward expansion aerial photography of the grid area; it also solves the problem that image control points cannot be deployed in areas with no signal; at the same time, it realizes the automatic sorting and production of three-dimensional data modeling tasks, improves the production efficiency and accuracy of three-dimensional building models, and reduces production costs and difficulties.

[0045] In some embodiments, before dividing the current area into a grid area composed of multiple grids, it also includes: determining whether there is a signal in the current area; if so, no processing is performed; otherwise, communication is performed through carrier phase differential technology; wherein, communication through carrier phase differential technology includes: setting a base station in a signal area, and adjusting the radio power according to the distance from the current area, setting a mobile station on a collection device and setting the power of the mobile station to be the same as that of the base station, and calculating the coordinates of the mobile station by receiving the coordinate signal of the base station. In this embodiment, the present application communicates in a signal-free area through two groups of RTK equipment, namely carrier phase differential equipment, wherein one group of RTK equipment is used as a base station, and one group of RTK equipment is used as a mobile station, and the precise geographic location information is received through the base station receiver, and the mobile station receiver receives the signal through the radio signal sending mode, and the three-dimensional coordinates and their accuracy of the mobile station are solved in real time through the carrier phase observation real-time differential technology.

[0046] In one implementation of the above embodiment, the radio power is adjusted according to the distance from the current area, including: if the straight-line distance from the current area to the base station setting point exceeds 3km, the base station needs to use an external radio to enhance the signal frequency; if the straight-line distance from the current area to the base station setting point is within 3km, the base station's built-in radio is used for signal transmission. The external radio is used to enhance the signal frequency to ensure communication between the base station and the mobile station.

[0047] In some embodiments, the current area is divided into a grid area composed of a plurality of grids, including: dividing the current area into a plurality of grid areas according to the flight altitude and distance, image shooting range, and flight time of the acquisition device. After each grid area is divided, the acquisition device performs aerial photography using the grid lines as a path, and flies the grid lines of all grids in sequence. Figure 2 , where 1 is a grid line and 2 is an outward flight line. The current area is divided into a grid area including multiple grids, so that the acquisition device flies along the grid lines. The grid area is a grid line pre-divided in the acquisition device before the acquisition device flies, so that the acquisition device flies according to the grid lines, wherein the acquisition device can be a camera drone.

[0048] In some embodiments, determining the expansion area of ​​the grid area includes: determining an expansion flight line on the periphery of the grid area, so that after each first grid is flown, the adjacent expansion area is flown immediately. When all the first grids are flown, the expansion area flight is completed. Among them, the area enclosed by the expansion flight line is larger than the area of ​​the grid area. In this embodiment, when formulating a route according to the flight grid range, flight collection is required for each grid expansion to ensure the integrity of the three-dimensional data model. In this embodiment, only the grids in the edge area need to be expanded, which can reduce the expansion range and improve production efficiency. The effect produced is consistent with the effect of flying each grid. And the flight expansion area is reduced, and the collection efficiency is improved. Specifically, the distance between the expansion flight line of the present application and the outer grid line of the grid area is 150-200 meters; it can be expanded along the flight altitude of 180 meters away from the grid area.

[0049] In some embodiments, the image data is processed, including: logically splicing multiple image data through block merging technology; performing individual grid filtering in each grid so that the data between adjacent grids can be used interchangeably; wherein the image data are all photo sets collected by multiple acquisition devices. In this embodiment, multiple image data are logically spliced ​​through block merging technology, including: recording the numbers, POS data and camera parameters of all photos in the grid in an XML file; merging the XML files in multiple grids. Among them, the numbers and POS data of all photos of a single grid are recorded in an XML file, and this XML file and the corresponding photos are blocks of the grid. Block merging is to merge the XML files of several grids. Performing individual grid filtering in each grid so that the data between adjacent grids can be used interchangeably. In this application, according to the computer performance, the individual grid is processed separately in blocks to improve the processing efficiency, specifically including: according to the XML file after the block merger, when extracting photos for one grid, the data of other grids around this grid are automatically extracted. After all grids are flown, the data is imported into the data processing system as a whole. The block merging function of the data processing system is used to logically connect all photos together, and then filter the individual grids to achieve data interoperability between adjacent grids and reduce circular expansion flights. Further reduce circular expansion flights. The data processing system can be any one of contextcapture, smart3d, and M3D.

[0050] In some embodiments, it also includes performing three-dimensional data modeling based on the image data, including: performing spatial triangulation processing on each grid based on the image data to generate aerial triangulation results; importing all aerial triangulation results into the modeling system in sequence, pointing the engine of the task sequence of the aerial triangulation results to the same path, and submitting the modeling in sequence.

[0051] In one implementation of the above embodiment, each grid is subjected to spatial triangulation processing to generate aerial triangulation results, including: spatial triangulation is performed by any one of the methods of simulation method, analytical method, flight strip method, independent model method, and ray bundle method, based on the photos, POS values, camera parameters, photo control points and connection points of the grid, to generate control triangulation results. The present application generates aerial triangulation results by inputting the photos, POS values, camera parameters, photo control points and connection points of the grid into the modeling system, and the modeling system produces aerial triangulation results through the spatial triangulation algorithm. The purpose of the triangulation algorithm is to calculate the accurate POS values ​​of all photos in a grid and match a certain number of photo connection points.

[0052] In one implementation of the above embodiment, 3D modeling is based on a computer cluster, and the connection between the computer and the aerial triangulation result processing project is based on a JOB file. It is only necessary to point the JOB path of all the aerial triangulation results to be processed to a file to achieve automatic sorting. Thus, modeling is completed. Among them, the modeling system can be any one of contextcapture, smart3d, and M3D.

[0053] This application reduces the outward expansion area of ​​the flight and improves the collection efficiency by performing outward expansion aerial photography of the grid area; it also solves the problem that image control points cannot be deployed in areas with no signal; at the same time, it realizes the automatic sorting and production of three-dimensional data modeling tasks, improves the production efficiency and accuracy of three-dimensional building models, and reduces production costs and difficulties.

[0054] Obviously, the above embodiments of the present application are merely examples for clearly illustrating the present application, and are not intended to limit the implementation methods of the present application. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A method for constructing a three-dimensional building model, characterized in that: The method comprises: Divide the current area into a grid area consisting of a plurality of grids, and determine an outer expansion area of ​​the grid area; Dividing the grid of the grid area into a first grid and a second grid according to whether it is adjacent to the outer expansion area; Performing flight photography along each of the grids in sequence to acquire image data, and after completing the flight of each of the first grids, continuing to perform flight photography along the outer expansion area adjacent to the current first grid; Processing the image data; The first grid is a grid connected to the outer periphery of the grid area and the outer expansion area, and the second grid is inside the grid area; the determining the outer expansion area of ​​the grid area comprises: determining an outer expansion flight line along the outer periphery of the grid area, wherein the area enclosed by the outer expansion flight line is larger than the area of ​​the grid area; The processing of the image data includes: Logically stitch multiple image data together through block merging technology; Performing individual grid filtering in each of the grids to allow data between adjacent grids to be mutually usable; The image data is a set of photos collected by multiple acquisition devices; the multiple image data are logically spliced ​​by block merging technology, including: The numbers, POS data and camera parameters of all photos in the grid are recorded in an XML file; Merge XML files in multiple grids; The filtering is performed in each grid to make data between adjacent grids interoperable, including: According to the XML file after the blocks are merged, when extracting photos from one of the grids, data of other grids around the grid are automatically extracted; The distance between the outward expansion flight line of the outward expansion area and the outer grid line of the grid area is 150-200 meters.

2. A three-dimensional building model construction method according to claim 1, characterized in that: Before dividing the current area into a grid area consisting of multiple grids, it also includes: Determine whether there is a signal in the current area; If yes, no processing is performed; otherwise, communication is performed through carrier phase differential technology; Among them, the communication through carrier phase difference technology includes: setting the base station in a signal area and adjusting the radio power according to the distance from the current area, setting the mobile station on the collection device and setting the power of the mobile station to the same as the base station, and calculating the coordinates of the mobile station by receiving the coordinate signal of the base station.

3. A three-dimensional building model construction method according to claim 2, characterized in that: The adjusting the radio power according to the distance from the current area includes: If the straight-line distance between the current area and the base station setting point exceeds 3km, the base station needs to use an external radio to enhance the signal frequency. If the straight-line distance between the current area and the base station setting point is within 3km, the base station's built-in radio is used for signal transmission.

4. A three-dimensional building model construction method according to claim 1, characterized in that: The step of dividing the current area into a grid area consisting of a plurality of grids includes: The current area is divided into multiple grid areas according to the flight altitude and distance, image photography range, and flight time of the acquisition equipment.

5. A three-dimensional building model construction method according to claim 1, characterized in that: The method further includes performing three-dimensional data modeling according to the image data, including: According to the image data, each of the grids is subjected to spatial triangulation processing to generate an aerial triangulation result; Import all the aerial triangulation results into the modeling system in sequence, point the engine of the task sequence of the aerial triangulation results to the same path, and then submit them for modeling in sequence.

6. A three-dimensional building model construction method according to claim 5, characterized in that: The step of performing spatial triangulation processing on each of the grids to generate spatial triangulation results includes: Spatial triangulation generates triangulation results based on grid photos, POS values, camera parameters, photo control points and connection points through any of the following methods: simulation method, analytical method, flight strip method, independent model method, and ray bundle method.

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