CN114396920A

CN114396920A - Topographic map space element obtaining method based on oblique photography

Info

Publication number: CN114396920A
Application number: CN202210041855.3A
Authority: CN
Inventors: 谢元礼
Original assignee: Northwest University
Current assignee: Northwest University
Priority date: 2019-03-06
Filing date: 2019-03-06
Publication date: 2022-04-26
Also published as: CN109883397A

Abstract

The invention discloses a topographic map space element acquisition method based on oblique photography, which relates to the technical field of geographic mapping and comprises the following steps: acquiring an oblique photography photo; performing aerial triangulation calculation on the oblique photography photo to obtain a map projection image and point cloud data; performing ground object plane extraction on the map projection image to obtain a line element, and processing point cloud data to obtain an elevation element; and editing the plane and elevation elements to obtain a topographic map. The invention integrates oblique photography and aerial triangulation techniques, establishes a non-stereo observation topographic map surveying and mapping method with separate operation of plane and elevation, and enables new workers to produce topographic maps without stereo observation training, thereby changing the traditional topographic map surveying and mapping method of stereography or multi-image observation and meeting the accuracy requirement of topographic map surveying and mapping.

Description

Topographic map space element obtaining method based on oblique photography

Technical Field

The invention relates to the technical field of geographic mapping, in particular to a topographic map space element (including plane and elevation elements) acquisition method based on oblique photography.

Background

The traditional topographic map surveying and mapping method for photogrammetry stereography adopts the operation flows of aerial triangulation, stereopair establishment, stereography and the like, the production mode of the topographic map is quite mature in algorithm, the space elements of the topographic map are obtained on a stereomodel, the space elements are used for fifty-six years in the world, and the method is still the mainstream mode for topographic map production of surveying and mapping units at present.

The mapping method used in the prior art is shown in fig. 2, and two insurmountable problems exist in the production practice: the first problem is that operators must carry out stereo observation, and the stereo observation capability usually needs to be trained for eight weeks to meet the production operation requirement; the second problem is that the elevation precision is difficult to meet the production specification requirement of large-scale maps, and a large amount of field measurement is required.

Disclosure of Invention

The invention provides a topographic map space element acquisition method based on oblique photography, which can solve the problems in the prior art.

The invention provides a topographic map space element acquisition method based on oblique photography, which comprises the following steps:

acquiring a multi-angle oblique photograph;

performing aerial triangulation calculation on the obtained oblique photography picture to obtain a map projection image synthesized by oblique photography and point cloud data;

and performing ground object plane processing on the map projection image synthesized by oblique photography to obtain a plane element, and processing point cloud data to obtain an elevation element.

Preferably, a single map projection image vectorization tracking observation technology of oblique photography synthesis is adopted to carry out non-stereo observation.

Preferably, the oblique photography picture is obtained by shooting with a photography platform.

Preferably, the photographing platform photographs using an oblique photographing camera.

The invention also provides a single-image non-stereo observation topographic map surveying and mapping method based on oblique photography, which is used for editing the plane and elevation elements obtained by the method to obtain a topographic map; the traditional surveying and mapping process is changed, innovativeness is achieved, the operation threshold is reduced, and practicability is achieved.

The topographic map space element acquiring method based on oblique photography has the advantages that:

1. the threshold of the professional skill of an operator is reduced, the method of drawing by wearing stereo observation glasses is avoided, and the training of stereo observation capability is not needed;

2. hardware configuration is reduced, professional accessories such as three-dimensional observation equipment and hand wheel foot plates are not needed, and ten thousand yuan of money is saved;

3. the operation efficiency is improved, the operation is not influenced by small image size, the operation is convenient, and the operation efficiency is improved by 3 times;

4. the topographic map precision is guaranteed, and the multi-baseline intersection and automatic aerial triangulation of oblique photography provide guarantee for the topographic map precision, particularly the elevation precision.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow chart of a method for topographic mapping provided by the present invention;

FIG. 2 is a flow chart of a topographical mapping method used in the prior art;

FIG. 3 is a map projection image of a campus generated using the present invention;

fig. 4 is a topographic map obtained from the map projection image and the dense elevation points of fig. 3.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, the present invention provides a topographic map space element acquiring method based on oblique photography, the method comprising the steps of:

shooting oblique photography photos at multiple angles by using a photography platform, wherein the photography platform can be a platform in various forms such as an unmanned aerial vehicle, a manned plane or a satellite, the photography platform adopts an oblique photography camera for shooting, and the oblique photography camera can adopt lens forms such as a single lens, a double lens, a three lens, a four lens, a five lens or a nine lens;

performing aerial triangulation calculation on the obtained oblique photography picture to obtain a high-quality map projection image and high-precision point cloud data;

carrying out single-image non-stereo observation on the map projection image to obtain plane elements, and processing point cloud data to obtain height elements such as contour lines, elevation points and the like;

and editing the plane elements and the elevation elements to obtain the topographic map.

Examples illustrate that:

the method is used for testing a certain campus in the city of Xian, the terrain of a test area is flat, the test area is divided into an east area and a west area by a road, the terrain is basically a building, the east area is mainly a high-rise building, the west area is mainly a multi-story building, and the area is 1 square kilometer. The five-lens oblique photography of the MD4-1000 unmanned aerial vehicle comprises one fixed-focus lens with 25mm downward view, four fixed-focus lenses with 35mm inclination, a focal length of the lenses is 20mm, the relative flight height is 160m, three times of flight are respectively carried out in the north-south direction and the east-west direction, 740 images are obtained, each image has 2000 ten thousand pixels, the ground sampling interval is 0.09m, and the course and the lateral overlapping degree are both 70%.

The area network control point is measured through a static GPS, and the check point is actually measured through an RTK. The 12 control points are distributed as shown by the white triangular area in fig. 3. The method comprises the steps of utilizing 12 control points and adding broken points and check points necessary for topographic map surveying to conduct oblique image multi-view aerial triangulation, automatically generating a map projection image as shown in figure 3, obtaining height elements such as contour lines and height points according to height information obtained by aerial triangulation on the basis of the map projection image by using plane elements, and finally obtaining a 1:500 topographic map as shown in figure 4 through editing processing.

When the accuracy of the topographic map is verified, 98 obvious geoobject points are selected as plane check points, 92 obvious geoobject points are selected as elevation check points, the check points are actually measured by using GPS RTK, errors are counted, the statistical result is shown in table 1, the error in the plane position is 0.29m, the error in the elevation is 0.14m, and the plane and elevation accuracy meets the requirements of GB/T15967-2008 topographic map aerial photogrammetry digital mapping specification 1:500 topographic map accuracy.

TABLE 1 statistical results of errors

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A topographic map space element acquisition method based on oblique photography is characterized by comprising the following steps:

acquiring a multi-angle oblique photograph;

and carrying out ground object plane vectorization processing on the map projection image synthesized by oblique photography to obtain a plane map element, and processing point cloud data to obtain an elevation element.

2. The terrain space element acquiring method based on oblique photography according to claim 1, wherein the non-stereoscopic observation is performed by using a single map projection image vectorized tracking observation technique of oblique photography combination.

3. The oblique photography based topographical spatial element acquisition method as recited in claim 1, wherein said oblique photography is taken using a photography platform.

4. The oblique photography based topographical spatial element acquisition method as recited in claim 3, wherein said photography platform employs oblique photography.