CN116385686B - Live-action three-dimensional model reconstruction method and system based on irregular oblique photography - Google Patents
Live-action three-dimensional model reconstruction method and system based on irregular oblique photography Download PDFInfo
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Abstract
The application discloses a real-scene three-dimensional model reconstruction method and a real-scene three-dimensional model reconstruction system based on irregular oblique photography, wherein the method comprises the steps of determining the level of the irregular oblique photography according to the topographic information of an area to be detected; presetting ground resolution and terrain conditions of each level according to parameters of the oblique photographing device, and determining aerial photography field schemes of each level, wherein the aerial photography field schemes comprise aerial photography heights; according to the aerial field scheme comprising aerial height, oblique photography is carried out on each level by utilizing an oblique photography device, so that images and data of each level are obtained; fusing images and data of all layers at one time, and carrying out space three calculation by assistance of GNSS/POS data; and reconstructing a live three-dimensional model of the region to be detected by means of three-dimensional model software according to the images and data of all the layers after the space three-dimensional calculation. The application improves the precision of reconstructing the live three-dimensional model of the region to be detected by using aerial images and data, and has accurate ground feature data and real and clear texture.
Description
Technical Field
The application discloses a real-scene three-dimensional model reconstruction method and system based on irregular oblique photography, and belongs to the technical field of three-dimensional model construction of aerial photogrammetry.
Background
Oblique photography is to mount a plurality of sensors on a flight platform, synchronously collect images from different angles of view such as a vertical angle, four inclinations and the like, and acquire abundant high-resolution surface textures of the ground, the top surface of a building and the side view. The method can truly reflect the ground object condition, acquire object texture information with high precision, and reconstruct a live-action three-dimensional model by means of advanced navigation positioning technology, fusion computer technology, image processing and other theories and methods.
Because the conditions of topography and landform are complex, and the altitude difference changes greatly (particularly, the topography irregular areas such as canyons, mountain areas and hills), the traditional aerial photography field operation scheme is a datum plane altitude weighted average value method in the aerial photography area, in order to ensure the safety of unmanned aerial vehicles and operation tasks, the unmanned aerial vehicle can be influenced by the highest point altitude in the to-be-tested area, and the aerial line laying can be generally carried out according to the mode of the high Cheng Jia safe distance of the highest point in the to-be-tested area, so that the flying height is obviously increased, the ground resolution of the area with a larger vertical line distance with the unmanned aerial vehicle is lower, aerial photography images and data quality are uneven, and the reconstructed real-scene three-dimensional model data is abnormal or wrong, texture distortion or deformation can not meet the precision requirement.
Disclosure of Invention
The application aims to provide a real-scene three-dimensional model reconstruction method and system based on irregular oblique photography, which are used for solving the technical problem that the reconstructed real-scene three-dimensional model is poor in quality due to low ground resolution caused by fixed airlines in the prior art.
The first aspect of the application provides a live-action three-dimensional model reconstruction method based on irregular oblique photography, which comprises the following steps:
determining the level of irregular oblique photography according to the topographic information of the area to be detected;
presetting ground resolution and terrain conditions of each level according to parameters of an oblique photographing device, and determining aerial photography field schemes of each level, wherein the aerial photography field schemes comprise aerial photography heights;
according to the aerial field scheme comprising aerial height, carrying out oblique photography on each level by utilizing the oblique photography device to obtain images and data of each level;
fusing images and data of all layers at one time, and carrying out space three calculation by assistance of GNSS/POS data;
and reconstructing a live three-dimensional model of the region to be detected by means of three-dimensional model software according to the images and data of all the layers after the space three-dimensional calculation.
Preferably, the determining the level of the irregular oblique photography according to the topographic information of the area to be measured specifically includes:
dividing the region to be detected into a plurality of units, and obtaining the relief degree of each unit;
taking the whole area to be measured as a first level of irregular oblique photography;
and determining the advanced level of the irregular oblique photography according to the topography relief of each unit and a preset threshold value.
Preferably, determining the level of the step of the irregular oblique photography according to the relief of the topography of each unit and a preset threshold value specifically includes:
dividing all units with the relief degree larger than a preset first threshold value into a second level;
dividing all units with the relief degree larger than a preset second threshold value into a third level, wherein the first threshold value is smaller than the second threshold value.
Preferably, the ground resolution and the topography condition of each level are preset according to the parameters of the oblique photographing device, and the aerial-photographing field scheme of each level is determined, wherein the aerial-photographing field scheme comprises aerial-photographing height, and specifically comprises the following steps:
determining the aerial altitude of each level according to a first formula:
wherein H is aerial photographing height, GSD is ground resolution of each preset level, f is lens focal length of the oblique photographing device, and alpha is pixel size of the oblique photographing device.
Preferably, the oblique photographing device performs oblique photographing on each of the levels, and specifically includes:
using the oblique photographing device to perform oblique photographing on a preset area in each hierarchy by combining preset oblique photographing parameters and terrain conditions;
the oblique photography parameters comprise course overlapping degree, side overlapping degree, course coverage range, side coverage range and the like.
Preferably, the heading overlap is not less than 75%;
the side overlap is not less than 65%;
the course coverage exceeds two baselines of a shot area or a partition boundary line;
the side coverage exceeds the shot area or the regional boundary line by not less than 50% of the image frame.
Preferably, the method fuses images and data of all layers at one time, and performs blank three-solution by assistance of GNSS/POS data, and specifically comprises the following steps:
acquiring images and data of all layers at one time, selecting accurately identifiable ground obvious object points on the images as image connection points, and marking the same-name image points;
and according to the marked images and data of all the layers, using necessary image points and ground control point coordinate values to assist in performing space three calculation by using GNSS/POS data.
A second aspect of the present application provides a real-scene three-dimensional model reconstruction system based on irregular oblique photography, comprising:
the hierarchy determining module is used for determining the hierarchy of the irregular oblique photography according to the topographic information of the area to be detected;
the aerial photography module is used for presetting the ground resolution and the terrain condition of each level according to the parameters of the inclined photographic device and determining an aerial photography field scheme of each level, wherein the aerial photography field scheme comprises an aerial photography height; according to the aerial field scheme comprising aerial height, carrying out oblique photography on each level by utilizing the oblique photography device to obtain images and data of each level;
the image data fusion module is used for fusing images and data of all levels at one time and assisting GNSS/POS data to perform space three calculation;
the real three-dimensional model reconstruction module is used for reconstructing a real three-dimensional model of the region to be detected by means of three-dimensional model software according to images and data of all levels after the space three-dimensional calculation.
Compared with the prior art, the method and the system for reconstructing the live-action three-dimensional model based on the irregular oblique photography have the following beneficial effects:
according to the method and the system, the levels of the irregular oblique photography are determined according to the topographic information of the area to be detected, so that each level has the respective aerial photographing height and ground resolution, the obtained images and data are more accurate, and the accuracy of reconstructing a real-scene three-dimensional model of the area to be detected by using aerial photographing images and data is further improved rapidly by fusing all the images and data at one time, and the ground feature data is accurate and true and clear in texture.
Drawings
FIG. 1 is a schematic flow chart of a real-scene three-dimensional model reconstruction method based on irregular oblique photography in an embodiment of the application;
FIG. 2 is a schematic view of a sectional area and a hierarchical plan view of an irregular oblique photography range according to an embodiment of the present application;
FIG. 3 is a longitudinal cross-sectional view of an irregular oblique photography (hierarchy) in accordance with an embodiment of the present application;
fig. 4 is a schematic structural diagram of a real-scene three-dimensional model reconstruction system based on irregular oblique photography in an embodiment of the application.
101 is a hierarchy determination module; 102 is a aerial camera module; 103 is an image data fusion module; 104 is a live three-dimensional model reconstruction module.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
The first aspect of the present application provides a method for reconstructing a real-scene three-dimensional model based on irregular oblique photography, as shown in fig. 1, including:
step 1, determining a level of irregular oblique photography according to topographic information of an area to be detected, which specifically comprises the following steps:
step 1.1, dividing the region to be measured into a plurality of units, and obtaining the relief of the topography of each unit.
The topographic relief means the difference between the highest point altitude and the lowest point altitude in a unit. It is a macroscopic indicator describing the topography of an area.
When the area to be measured is divided into a plurality of units, the embodiment of the application can adopt an equipartition method and can also divide the area to be measured into a plurality of unequal units according to preset requirements, wherein the preset requirements can be that the topography fluctuation in each unit is larger than a preset minimum threshold value, so that the problem that the follow-up determined irregular inclined photographing level is inaccurate due to the fact that the divided units are too small and only comprise valley areas and the topography fluctuation of the valley areas is small is solved.
Further, the number of units divided in the present application is not particularly limited, and may be determined according to the specific case.
And 1.2, taking the whole region to be measured as a first level of irregular oblique photography.
In the embodiment of the application, the first level is defined as the whole area to be measured, when oblique photography is performed, the influence of the elevation of the highest point in the area to be measured must be considered in the course of laying of the oblique photographic device, and the course is usually finished according to the way of the high Cheng Jia safety distance of the highest point in the area to be measured, so that the flying height is obviously increased, the ground resolution of the area with a larger vertical distance from the unmanned aerial vehicle is lower, aerial images and data quality are uneven, and the reconstructed real-scene three-dimensional model data is abnormal or wrong, texture distortion or deformation, and cannot meet the precision requirement. Therefore, in the embodiment of the application, after the region to be detected is judged to be the region with complicated topography and landform conditions and large height difference change (particularly, irregular topography regions such as canyons, mountain areas and hills) according to the topography fluctuation, the topography fluctuation and a preset threshold value are further calculated, and the advanced level of irregular oblique photography is determined, as shown in step 1.3. If the terrain of the area to be measured is judged to be gentle according to the terrain fluctuation, the first level can be used for oblique photography.
And 1.3, determining the advanced level of the irregular oblique photography according to the relief degree of the topography of each unit and a preset threshold value.
In the embodiment of the present application, the number of the determined hierarchical levels may be determined according to specific situations, and the present application is not limited thereto. For example:
dividing all units with the relief degree larger than a preset first threshold value into a second level;
dividing all units with the relief degree larger than a preset second threshold value into a third level, wherein the first threshold value is smaller than the second threshold value.
According to the embodiment of the application, the advanced level is determined according to the topography fluctuation degree and the preset threshold value, so that the region with larger fluctuation degree change can be screened out from the region to be detected, and the aerial image and data of the region can be obtained by adopting the aerial image scheme operation such as the adaptive aerial image height and the like for the region, thereby improving the accuracy of the reconstructed real-scene three-dimensional model of the whole region to be detected.
Step 2, presetting ground resolution and terrain conditions of each level according to parameters of the oblique photographing device, and determining aerial photography field schemes of each level, wherein the aerial photography field schemes comprise aerial photography heights and specifically comprise:
determining the aerial altitude of each level according to a first formula:
wherein H is aerial photographing height, and the unit is m; GSD is the ground resolution (ground sampling interval) of each preset level, and the unit is m; f is the focal length of the lens of the oblique photographing device, and the unit is mm; alpha is the pixel size of the oblique photographing device in μm.
In the embodiment of the application, the oblique photographing device is a digital aerial photographing system formed by an aircraft carrying a camera with an oblique photographing function and a GNSS/POS function. The present application is not particularly limited thereto.
Step 3, according to the aerial field project including aerial height, utilizing the oblique photographing device to perform oblique photographing on the preset area in each level to obtain images and data of each preset area, wherein the method specifically comprises the following steps:
according to the aerial photography height, utilizing an oblique photography device to conduct oblique photography on a preset area in each level by combining preset oblique photography parameters and terrain conditions;
wherein the oblique photography parameters include heading overlap, side overlap, heading coverage, and side coverage. The requirement on the parameters in the embodiment of the application is that the course overlap degree is preferably not less than 75%; the side overlap is preferably not less than 65%; heading coverage exceeds two baselines of a shot area or a partition boundary line; the lateral coverage exceeds the shot or zoned boundary by no less than 50% of the image frame.
Further, in the embodiment of the present application, the preset area in each hierarchy is specifically:
for the first level, the preset area is the whole area to be measured;
for the advanced hierarchy, the preset area in the corresponding hierarchy is: and taking the area in the preset range at the lowest point corresponding to each terrain relief in the hierarchy as a preset area, so as to avoid the influence of the highest point of the terrain in the hierarchy unit on aerial photography.
In the embodiment of the application, before the oblique photography is performed on the preset area in each level by utilizing the oblique photography device according to the aerial photography height and combining the preset oblique photography parameters and the terrain conditions, necessary ground control points and image control points are also required to be distributed in the area to be tested. The number and arrangement modes of the ground control points and the image control points are determined according to actual conditions, and the application is not limited to the above.
After the ground resolution of each level is determined, the aerial photographing height of each level inclined photographing device can be determined, and then the aerial photographing height of the corresponding level is adopted to perform inclined photographing on the preset area in each level, so that the image and the data of each preset area are obtained.
Step 4, fusing images and data of all layers at one time, and performing blank three-resolution by assistance of GNSS/POS data, wherein the method specifically comprises the following steps:
step 4.1, acquiring images and data of all layers at one time, selecting accurately identifiable ground obvious object points on the images as image connection points, and marking the same-name image points;
and 4.2, performing space three-dimensional calculation together with GNSS (global navigation satellite system)/POS (onboard positioning and orientation system) data by utilizing necessary coordinate values of image control points and ground control points according to the marked images and data of all layers (in this example, light beam method area network space triangulation is adopted).
The method comprises the steps of performing pattern recognition (selecting image connection points from overlapping parts of all level images by using a point feature extraction operator, performing local multipoint relaxation image matching on each connection point to obtain homonymous points of the point in all level images, performing manual intervention if necessary, performing image connection through spatial similarity transformation, and bringing the homonymous points into the same coordinate system) and multi-view image matching (performing feature matching on all level images and data, conducting a feature matching result of a previous layer of image to a next level until all level images are subjected to precise matching by using least square image matching), performing turning points to obtain connection point coordinates of all level images, and providing the connection point coordinates for adjustment software to perform calculation (determining spatial positions of the connection points in the selected coordinate system and orientation parameters of all level images).
The adjustment software used therein is not limited in this regard.
In the embodiment of the application, the object points with obvious ground surface can be accurately identified, and the natural points with obvious objects or characteristics which exist in the field and are not easy to damage in the image are selected.
And 5, reconstructing a live three-dimensional model of the region to be detected by means of three-dimensional model software according to images and data of all levels after the space three-dimensional calculation, wherein the method specifically comprises the following steps:
and inputting all images and data of all levels after the three-dimensional calculation into three-dimensional model software, and reconstructing a live-action three-dimensional model of the region to be detected. The three-dimensional model software in the embodiment of the present application may be ContextCapture Master software, which is not limited in this regard.
The method of the present application will be described in more specific examples.
1. Aerial photography operation task scope
The region of this embodiment is located in the canyon region of the Weibei plateau (where the river passes through the bottom), the maximum height difference (i.e., the relief of the terrain) is about 600m, the rock walls on both sides of the valley are steep, and many places are in a reverse slope shape. The depth of the canyon at the hanging bridge is 170m, the narrowest part of the river channel at the bottom is only 15m, the maximum width of the upper part is 175m, and the canyon is narrow and deep, and the valley cannot pass through.
2. Oblique photographing device
In the embodiment, the Dajiang eidolon 4Pro unmanned aerial vehicle is provided with an aerial camera (model: DJI FC 6310), the focal length is 8.8mm, the GPS/GLONASS dual mode is adopted for positioning and recording image position information, and the pixel size of a lens carried by the Dajiang eidolon 4Pro unmanned aerial vehicle is 2.4123 mu m.
3. Image control point selection and measurement
The bottom of the canyon is free of traffic roads, is difficult to reach and has rivers to pass through, so that the valley bottom cannot be provided with image control points, and the image control points are all arranged in the area above the edge (hanging bridge) of the canyon.
The image control point is scattered on the open ground with lime, the shape is L-shaped, the single-side length of the line is greater than 1.0m, the width is greater than 0.15m, the position of the measuring point is selected as the outer corner of the L-shaped corner, and the measuring is carried out according to the precision of the map root point by adopting a GPS-RTK operation method. The roll call is composed of codes and numbers, and is uniformly compiled, and the whole embodiment area has no repeated number.
4. Aerial photography design and implementation
In this embodiment, according to the relief of the terrain and a preset threshold, the level of irregular photography is determined to be three levels through repeated demonstration after on-site investigation, and according to the preset ground resolution of each level, three different aerial heights are determined, as shown in fig. 2, the outermost ring formed by gray shaded lines in the figure is a first level, the middle ring formed by white lines passing through a DZ07 character is a second level, and the innermost ring formed by white lines passing through a DZ05 character is a third level. The first level aerial fly is selected at a position on the right shore (the dam axis is the arc through DZ 06) above the suspension bridge 30m. The second and third levels are flown with manual mode for ensuring unmanned equipment and operation safety due to instability or lack of GPS/GLONASS signals.
And determining the aerial altitude according to the preset ground resolution of each level and the altitude calculation of the highest point in the corresponding level, wherein the preset ground resolution is the average value.
In the embodiment of the application, the aerial photographing height of the first level is 300m, the aerial photographing height of the second level is 150m, and the aerial photographing height of the third level is 30m.
(1) When the aerial photography is carried out at the first level, the aerial photography image is mainly used for connecting global ground control points and image control points, and the unmanned aerial vehicle is used for executing the automatic mode aerial photography in a way of planning the aerial route by aerial photography software. The aerial photographing area is the outermost ring in FIG. 2, the maximum aerial height 470m relative to the bottom of the river channel is about 5cm in ground resolution of the ridge at the height, and the ground resolution of the bottom of the river channel is about 13cm.
(2) When the second level is used for aerial photography, the aerial photography range is as the middle circle of fig. 2, the ground resolution of the high area is about 4cm, the maximum aerial height at the bottom of the canyon is 320m, and the ground resolution at the bottom of the river channel is about 9cm; in order to avoid the influence of mountain bodies on the safety of unmanned aerial vehicle equipment, unmanned aerial vehicle manual mode aerial photography is assisted.
(3) When the third level is used for aerial photography, the aerial photography range is as the innermost ring in the figure 2, the maximum aerial height 200m relative to the valley bottom is selected, so that the aerial photography ground resolution of the valley bottom can reach 5cm, meanwhile, aerial photography images and textures of the side walls of the two sides of the canyon and the valley bottom are true and clear, the aerial photography is safe, ground objects such as rock walls and hanging bridges are avoided from being impacted, the aerial photography height aerial photography also adopts a manual mode to fly at ultra-low altitude, the rock walls on the two sides of the canyon are closely attached, and finally the aerial photography image ground resolution of the bottom of the canyon is better than 5cm.
The different voyage photographic longitudinal sectional views are shown in figure 3.
5. Design of aerial photography technical parameters
Heading overlap is greater than 75% and side overlap is greater than 65%. The heading covers two base lines beyond the shot boundary, and the lateral coverage exceeds 50% of the image frame beyond the shot boundary.
6. Image quality evaluation
The aerial image is clear, the gradation is rich, the contrast is moderate, and the tone is soft; fine features that are compatible with the ground resolution can be identified.
7. Image and data fusion processing
In this embodiment, the beam method is used to solve for the space three by domain network method. Three layers of images and data of the embodiment are obtained at one time, natural object points with markedness on the images are selected as image connection points, and the natural object points are marked as homonymous image points;
and according to the fused images and data of all the layers, the necessary ground control points and image control point coordinate values are utilized to assist in carrying out space three-dimensional calculation by using GPS/POS data of the Dajiang unmanned aerial vehicle together by means of a adjustment program, and the three-dimensional model software is used for reconstructing a real-scene three-dimensional model of the example region.
8. Reconstruction of live-action three-dimensional model
The modeling processing workstation adopts parallel GPU frame hardware, and the solid state disk storage can ensure the rapid reading and high-efficiency calculation of data. In addition, the parallel processing capability greatly improves the computer speed and reduces the running time. And reconstructing the live-action three-dimensional model by using an air three-dimensional calculation result as a data source and using the feature points obtained by air triangulation processing as modeling feature points.
According to the three-layer image and data obtained by aerial photography, the embodiment reconstructs a live-action three-dimensional model by means of three-dimensional model software, and truly restores the spatial position, natural form and real texture of the ground object, namely the live-action three-dimensional model. The reconstruction process has larger calculation task amount, and in order to improve the data processing speed, the camera is divided into a plurality of model blocks for cluster processing in the processing process.
The final three-dimensional model product format is output: 3MX, OSGB, STL, etc. Other accessory products are: orthographic images, point clouds, and the like.
9. Precision detection of live-action three-dimensional model
The GPS-RTK and total station field in the aerial photographing area collect 73 broken points as check points, after the real-scene three-dimensional model is rebuilt, the point elevation of the corresponding position is collected on the real-scene three-dimensional model product according to the corresponding position of the check point, and the calculation elevation is poorer to carry out precision statistics, as shown in table 1. Calculating an error m in an elevation annotation point according to a calculation formula of the same-precision detection by utilizing the elevation difference of the check point acquired by the actual measurement point and the actual three-dimensional model Pouring 。
TABLE 1 elevation annotation point accuracy statistics
As can be seen from table 1:
(1) When the equal-altitude distance of 1 meter is adopted, the rough difference rate of poor elevation mark points is 16 percent, which exceeds 5 percent specified by the limit difference.
(2) When the equal-altitude distance of 2 meters is adopted, the rough difference rate of the poor altitude marking points is 1%, and the error m in the altitude marking points Pouring Is 0.33 meter, meets the standard requirements.
Therefore, according to statistical analysis of detection results, it is considered that the elevation precision of the live-action three-dimensional model of the embodiment can reach 1 with a basic equal-altitude distance of 2 meters in a mountain area: the elevation precision requirement of the topographic map with the 500-1:1000 scale is high.
The three-dimensional model of the background canyon section in the Weibei area, which is obtained by the application, not only can realize the functions of measuring the coordinates and the elevations of any point, the distance between any two points, the slope surface area in any polygonal area, the filling volume and the like, but also can enable a user to clearly view the real surface characteristics such as the rock texture of the canyon side wall indoors, and has great engineering value.
Because the aerial photographing height directly influences the ground resolution of the acquired data, the aerial photographing image and the data with relative heights are regulated at the flying spot, so that the data precision of higher positions is ensured, and the data precision requirement of lower positions (the bottoms of riverways, canyons and the like) cannot be met. Therefore, the application needs to collect images and data at different heights by adopting a regional and layered aerial photography mode according to the actual ground resolution requirement, and the change of the coverage area accords with the target task more along with the rising or the falling of the aerial photography height. On the premise of ensuring the aviation safety, images and data with different aerial heights (different resolutions) are acquired, so that the accuracy of the follow-up reconstructed live-action three-dimensional model can be ensured to meet the requirements.
Through irregular oblique photography flight operation, aerial photography images and data are acquired at one time, and then are subjected to image data fusion connection processing, so that the practical application obtains breakthrough progress.
The second aspect of the present application provides a live-action three-dimensional model reconstruction system based on irregular oblique photography, as shown in fig. 4, which comprises a hierarchy determining module 101, a aerial photographing module 102, an image data fusion module 103 and a live-action three-dimensional model reconstruction module 104.
The hierarchy determining module is used for determining the hierarchy of irregular oblique photography according to the topographic information of the area to be detected;
the aerial photography module is used for determining an aerial photography field scheme of each level according to the ground resolution and the terrain condition of each level preset by the parameters of the oblique photographic device, wherein the aerial photography field scheme comprises an aerial photography height; according to the aerial field scheme comprising aerial height, oblique photography is carried out on each level by utilizing an oblique photography device, so that images and data of each level are obtained;
the image data fusion module is used for fusing images and data of all levels at one time and carrying out space three calculation by assisting with GNSS/POS data;
the real three-dimensional model reconstruction module is used for reconstructing a real three-dimensional model of the region to be detected by means of three-dimensional model software according to images and data of all levels after the space three-dimensional calculation.
The present application is not limited to the above embodiments, but is not limited to the above embodiments, and any person skilled in the art will have obvious modifications and modifications equivalent to those of the equivalent embodiments, and can make various changes and modifications without departing from the scope of the present application.
Claims (7)
1. The utility model provides a real scene three-dimensional model reconstruction method based on irregular oblique photography, which is characterized by comprising the following steps:
dividing the region to be detected into a plurality of units, and obtaining the relief degree of the topography of each unit;
taking the whole area to be measured as a first level of irregular oblique photography;
determining an advanced level of irregular oblique photography according to the topography relief of each unit and a preset threshold value;
presetting ground resolution and terrain conditions of each level according to parameters of an oblique photographing device, and determining aerial photography field schemes of each level, wherein the aerial photography field schemes comprise aerial photography heights;
according to the aerial field scheme comprising aerial height, carrying out oblique photography on each level by utilizing the oblique photography device to obtain images and data of each level;
fusing images and data of all layers at one time, and carrying out space three calculation by assistance of GNSS/POS data;
and reconstructing a live three-dimensional model of the region to be detected by means of three-dimensional model software according to the images and data of all the layers after the space three-dimensional calculation.
2. The method for reconstructing a real-scene three-dimensional model based on irregular oblique photography according to claim 1, wherein determining the advanced level of the irregular oblique photography according to the relief of the topography of each unit and a preset threshold value specifically comprises:
dividing all units with the relief degree larger than a preset first threshold value into a second level;
dividing all units with the relief degree larger than a preset second threshold value into a third level, wherein the first threshold value is smaller than the second threshold value.
3. The method for reconstructing a three-dimensional model of a real scene based on irregular oblique photography according to claim 1, wherein the ground resolution and the topography condition of each level are preset according to parameters of an oblique photography device, and the aerial field scheme of each level is determined, and the aerial field scheme comprises aerial altitude, and specifically comprises:
determining the aerial altitude of each level according to a first formula:
in (1) the->For aerial altitude, < > in->Ground resolution for each level preset, +.>For the lens focal length of the oblique photography device, < >>Is the pixel size of the oblique photographing device.
4. The method for reconstructing a three-dimensional model of a live action based on irregular oblique photography according to claim 1, wherein oblique photography is performed on each of the levels by using the oblique photography device, specifically comprising:
using the oblique photographing device to perform oblique photographing on a preset area in each hierarchy by combining preset oblique photographing parameters and terrain conditions;
the oblique photography parameters include heading overlap, side overlap, heading coverage, and side coverage.
5. The method for reconstructing a real-scene three-dimensional model based on irregular oblique photography according to claim 4, wherein the course overlap is not less than 75%;
the side overlap is not less than 65%;
the course coverage exceeds two baselines of a shot area or a partition boundary line;
the side coverage exceeds the shot area or the regional boundary line by not less than 50% of the image frame.
6. The method for reconstructing a real-scene three-dimensional model based on irregular oblique photography according to any one of claims 1 to 5, wherein the method comprises the steps of merging images and data of all layers at one time, and performing space three-dimensional calculation with assistance of GNSS/POS data, and specifically comprises the following steps:
acquiring images and data of all layers at one time, selecting accurately identifiable ground obvious object points on the images as image connection points, and marking the same-name image points;
and according to the marked images and data of all the layers, using coordinate values of image control points and ground control points to assist in performing space three calculation by using GNSS/POS data.
7. An irregular oblique photography-based live-action three-dimensional model reconstruction system, comprising:
the hierarchy determining module is used for dividing the region to be detected into a plurality of units and acquiring the relief degree of each unit; taking the whole area to be measured as a first level of irregular oblique photography; determining an advanced level of irregular oblique photography according to the topography relief of each unit and a preset threshold value;
the aerial photography module is used for presetting the ground resolution and the terrain condition of each level according to the parameters of the inclined photographic device and determining an aerial photography field scheme of each level, wherein the aerial photography field scheme comprises an aerial photography height; according to the aerial field scheme comprising aerial height, carrying out oblique photography on each level by utilizing the oblique photography device to obtain images and data of each level;
the image data fusion module is used for fusing images and data of all levels at one time and assisting GNSS/POS data to perform space three calculation;
the real three-dimensional model reconstruction module is used for reconstructing a real three-dimensional model of the region to be detected by means of three-dimensional model software according to images and data of all levels after the space three-dimensional calculation.
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