JP2001141454A - Method for checking aerial photogrammetry by using triplet technique - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of measured results of aerial photogrammetry. SOLUTION: In a method for checking aerial photogrammetry, a series of aerial photographs is taken at a prescribed photography lapping rate along a photographing course covering an area to be photographed and three continuous aerial photographs are selected out of the aerial photographs. Then the AD-converted data of the aerial photographs are prepared by regarding the left and right-side photographs as left and right photographs and the photograph between the left and right photographs as a central photograph and three-dimensional measurement is performed by a left-side model based on the left and central photographs and a right-side model based on the right and central photographs. Thereafter, corresponding points in the measured results by the left- and right-side models are compared with each other and the three-dimensional measurement by the left- and right-side models is repeatedly redone until coincidence is obtained between the corresponding points. When the coincidence is obtained, three-dimensional coordinate values are found by performing three-dimensional measurement by both end models based on the left and right photographs by using the photographic coordinated values of the coincident corresponding point. Therefore, the reliability of the measured results of aerial photogrammetry can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to aerial photogrammetry, and more particularly to an aerial photogrammetry checking method for improving the reliability of measurement results in aerial photogrammetry.

[0002]

2. Description of the Related Art As a countermeasure against the sedimentation of a dam in a mountainous area, it is necessary to find the secular change of sediment in the mountainous area. If necessary,
The landslide survey in the mountainous area must be carried out. For the three-dimensional measurement method for the landslide, the survey area is usually located deep in the mountain and extends over a wide area. Was very difficult. Therefore, conventionally, a three-dimensional measurement method using a stereo aerial photograph of the mountain area most recently photographed and a stereo aerial photograph newly photographed has been adopted. In other words, this conventional three-dimensional measurement method calculates the difference between the three-dimensional coordinates of a predetermined point measured from a previously captured stereo aerial photograph and the three-dimensional coordinates of the same point measured from a newly captured stereo aerial photograph. The amount of sediment due to the landslide was calculated.

[0003]

However, this conventional 3
The dimension measurement method outputs the measurement result by one stereo matching, and it cannot be said that the reliability of the measurement result is sufficient. In particular, in a steep terrain, the parallax difference is too large, so that stereo viewing is possible but measurement is not possible. In addition, in a steep terrain, the left and right aerial photography patterns are different, and stereo viewing is sometimes impossible.
On collapsed terrain, the pattern was flat and white, and stereo vision was often impossible.

A so-called AUTO-3D measuring method as disclosed in Japanese Patent Publication No. Hei 16-16930 filed by the present applicant is available as a measuring method of this kind. After applying it,
The following problems remain. That is, the current AU
In the TO-3D measurement method, an image correlation method is used. However, in the case of a flat pattern without a stereo pattern, the correlation coefficient is 1. everywhere even if it is not the same point (corresponding point).
It becomes 0, and it is not possible to judge pass / fail with only the correlation coefficient. In other words, in the current method, even when stereoscopic viewing is not possible due to occlusion, different patterns with a correlation coefficient of 0.8 to 0.9 are regarded as the same pattern and judged to be good, and therefore, sufficient reliability is obtained. No sexual measurements could be obtained.

It is an object of the present invention to provide an aerial photogrammetry checking method using a triplet method, which can solve the above-mentioned problems of the prior art.

[0006]

According to the present invention, a point within the photographing target area is determined based on a series of aerial photographs taken at a predetermined photographing lap rate along a photographing course covering the photographing target area. In the aerial photogrammetry check method for obtaining a three-dimensional coordinate value, three consecutive aerial photographs are selected from the series of aerial photographs, and an aerial photograph located on the left side of the three aerial photographs is left. The photograph, the aerial photograph located on the right side is the right photograph, the aerial photograph located between the left photograph and the right photograph is the central photograph, AD conversion data of each photograph is created, and the left photograph and the central photograph are 3D measurement based on the left model based on the right model and 3D measurement based on the right model based on the right photograph and the center photograph. Correspondence between the measurement result by the left model and the measurement result by the right model And repeat the three-dimensional measurement by the left model and the three-dimensional measurement by the right model until the coincidence of the corresponding points is obtained, and use the corresponding point photograph coordinate values in which the coincidence of the corresponding points is found. It is characterized in that three-dimensional coordinates are obtained by performing three-dimensional measurement using a two-end model based on the left photograph and the right photograph.

According to one embodiment of the present invention, the comparison of the corresponding points is performed by generating a square mesh on the central photograph and obtaining left and right corresponding points based on the points.

[0008] According to another embodiment of the present invention, the aforementioned 3
The selection of the aerial photograph is repeatedly performed after obtaining the three-dimensional coordinate values, and the selected photograph is shifted to the right by one from the previous selection, thereby obtaining the photographing target area. A three-dimensional coordinate value over the whole is obtained.

According to one embodiment of the present invention, the predetermined photographing lap rate is 80%.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in more detail with reference to the accompanying drawings according to embodiments and examples of the present invention.

FIG. 1 is a flowchart showing the overall procedure of the aerial photogrammetry check method of the present invention, and FIG.
It is a figure for explaining the left model, the right model, and both ends model used in the aerial photogrammetry check method of the present invention.

For example, when the aerial photogrammetry check method of the present invention is applied to the investigation of a landslide in a mountainous area, first, a photographing course covering an area to be imaged including the mountainous area to be surveyed should be followed. Need to take a series of aerial photographs. In order to ensure that all parts are taken over the target area before actually taking such an aerial photograph, it is necessary to take pictures at what kind of flight course and at what kind of shooting positions and shooting intervals. It is necessary to make a shooting plan in advance as to whether to go. For this reason, an aerial photography simulation plan is prepared as shown in step 11 of FIG.

This aerial photographing simulation plan is based on what kind of photographing course,
It is possible to find out what shooting lap rate and what course shooting start position at which aerial photograph can be taken to minimize the unprojectable area without actually flying the aircraft. is there. The applicant has disclosed a method for simulating an aerial photography plan for this purpose in the specification and drawings of another patent application.
According to this, in an aerial photography plan simulation method for simulating an imaging plan for taking an aerial photograph covering an imaging target area, three-dimensional mesh data representing terrain including at least the imaging target area is prepared, and an imaging scale, Along with parameters representing shooting conditions such as a focal length and a film size, the values are input to a computer, a non-projectable area threshold value is set, a shooting course for the shooting target area is set, and a shooting lap rate is set along the shooting course. Setting, setting the course shooting start position, setting the shooting position in the course, calculating the numerical value of the non-projectable area at the shooting position in the course, and calculating the numerical value of the calculated non-projectable area and the non-projectable area. The quality of the shooting plan is determined by comparing the threshold value with the threshold value.

Next, according to the photographing plan established in step 11 as described above, in step 12, a series of aerial photographs are photographed along a photographing course covering the photographing target area. Usually, the area subject to the landslide survey includes a lot of steep terrain. To minimize the parts that cannot be measured due to occlusion, the shooting lap rate is set to 80%, and the shooting baseline length of stereo photography is shortened as much as possible. .

The aerial photograph thus photographed is processed in step 13, aerial triangulation is performed in step 14, and aeronautical triangulation error correction is performed in step 15. In order to enable measurement by a computer, AD conversion data corresponding to each image data of a series of aerial photographs thus obtained is created in step 16.

Next, according to the triplet method of the present invention, the three-dimensional coordinate values (X,
(Y, Z values). First, step 1
In step 7, three-dimensional measurement is performed using the left model, and in step 18, three-dimensional measurement is performed using the right model. Here, the three-dimensional measurement in the left model and the right model will be described in detail with particular reference to FIG.

FIG. 2 shows a sequence of three consecutive aerial photographs taken out of a series of aerial photographs taken at an imaging lap rate of 80% along an imaging course. In FIG. 2, the left aerial photograph is referred to as a left photograph 1, the right aerial photograph is referred to as a right photograph 3, and the aerial photograph between the left photograph 1 and the right photograph 3 is referred to as a center photograph 2. In the embodiments described below, the left photograph 1 is the first aerial photograph among the aerial photographs taken along the photographing course, the center photograph 3 is the aerial photograph taken next,
The right photograph 2 is an aerial photograph taken next.

The left model is a pair of stereo aerial photographs composed of a left photograph 1 and a center photograph 2. In step 17, three-dimensional measurement using the left model is performed using the corresponding AD conversion data. So-called AUT
The three-dimensional coordinate value of each point is obtained according to the O-3D measurement method. Similarly, the right model is a pair of stereo aerial photographs composed of the center photograph 2 and the right photograph 3. In step 18, the corresponding A / D conversion data is used and the above-described AUTO-3D measurement method is used. The three-dimensional coordinate values of each point are obtained.

Next, the corresponding points are compared in step 19, which is performed by comparing the three-dimensional coordinate values obtained in step 17 with the three-dimensional coordinate values obtained in step 18. . Since it is necessary to check the corresponding points at the same lap rate at a shooting lap rate of 80%, a square mesh is generated as shown by diagonal lines on the central photograph 2 of the triplet, and the left and right are determined based on these points. Adopt the method of finding the corresponding point of. As described above, the same point is double-measured on the central photograph using three consecutive aerial photographs, and is converted into a ground coordinate value. When both are close to the same value, each AUTO-3D is measured.
It is determined that the pattern matching of the corresponding point in the three-dimensional measurement by the measurement method is correct, and the measurement result is adopted as reliable data.

On the other hand, if the measurement result by the left model and the measurement result by the right model do not match and are considerably different, it is determined that a matching error has occurred in the corresponding point, and the process returns to step 17 and step 18 to return to the left model. And the measurement by the right model are performed again by selecting the corresponding point again. Then, in step 19, the corresponding points are compared again. Thus, such a procedure is repeated until it is determined that matching of the corresponding points has been correctly performed.

In step 19, after it is determined that the measurement results by the left model and the right model are reliable, the process proceeds to step 20, where the procedure for correcting the three-dimensional coordinate values by the both-end model is started. Here, the two-end model is a pair of stereo aerial photographs including a left photograph 1 and a right photograph 3 as shown in FIG.

In the present invention, the reason why the measurement result is corrected in step 20 is as follows. In particular, when the measurement target area includes a lot of steep terrain, matching of the corresponding points is better in the left model and the right model (80%) with a short imaging base length and a large imaging lap rate (80%). Although the reliability is high, the measurement accuracy of the Z value indicating the ground height among the three-dimensional coordinate values to be measured is better than that of the three-dimensional measurement using the two-end model with a long imaging base length and a small imaging lap rate (60%). Is considered to be higher.

In step 20, the three-dimensional measurement using the two-end model is performed to obtain the three-dimensional coordinate values of each point in accordance with the so-called AUTO-3D measurement method using the corresponding AD conversion data. The matching of the corresponding points in this case is performed by selecting, as the corresponding points, those which have been confirmed as reliable in step 19.

Finally, in step 21, the three-dimensional coordinate value of each point is determined as a correct three-dimensional measurement result. Here, the determination is made by determining the X and Y values of the three-dimensional coordinate values. Adopts the measurement result of the left model or the right model confirmed as having no matching error of the corresponding point in step 19, and sets the Z value of the three-dimensional coordinate value to the measurement result of the both end model in step 20. It is done in a way of adoption. In terms of measurement accuracy, the measurement results of the two-end model are the most accurate in terms of Z-value measurement. However, even if the confirmation measurement values of the left model and the right model are the same, measurement may not be possible due to occlusion in both models. But
In this case, the average value of the respective measurement results of the left model and the right model with an imaging lap ratio of 80% is adopted.

In order to obtain three-dimensional coordinate values of all points in the photographing target area, measurement based on one set of photographs is repeated for the three photographs of the left photograph, the central photograph, and the right photograph as described above. At this time, the photograph to be selected as the left photograph is shifted one position to the right.

In the above description of the embodiment, the photographing lap rate is set to 80%. However, the present invention is not limited to such a value, and an arbitrary photographing lap rate can be selected. For example, when it is desired to measure a region including a lot of extremely steep terrain, it is conceivable to set the shooting lap rate to 80% or more, for example, 90%.

[0027]

According to the present invention, the reliability of the measurement result by the aerial photogrammetry can be enhanced, and particularly, the reliability of the measurement result of the area including the steep terrain can be increased. Therefore, the present invention is effective when applied to a survey of landslides and the like in which a region including a lot of steep terrain often becomes a survey target.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an overall procedure of an aerial photogrammetry check method according to the present invention.

FIG. 2 is a diagram for explaining a left model, a right model, and both end models used in the aerial photogrammetry checking method of the present invention.

[Explanation of symbols]

 1 Left photo 2 Center photo 3 Right photo

Claims (4)

[Claims] 1. An aerial photograph for obtaining a three-dimensional coordinate value of a point in the photographing target area based on a series of aerial photographs photographed at a predetermined photographing lap rate along a photographing course covering the photographing target area. In the survey check method, three consecutive aerial photographs are selected from the series of aerial photographs, and an aerial photograph located on the left side of the three aerial photographs is a left photograph, and an aerial photograph located on the right side is a right photograph. A photograph, an aerial photograph located between the left photograph and the right photograph are defined as a central photograph, AD conversion data of each photograph is created, and three-dimensional measurement is performed by a left model based on the left photograph and the central photograph. 3 based on the right model based on the right photograph and the center photograph
Performs dimensional measurement, compares corresponding points between the measurement results by the left model and the measurement results by the right model, and performs three-dimensional measurement by the left model and by the right model until a match of the corresponding points is obtained. Calculating the three-dimensional coordinate values by performing the three-dimensional measurement again and performing three-dimensional measurement with the two-end model based on the left photograph and the right photograph using the corresponding point photograph coordinate values in which the corresponding points coincide with each other; A method for checking aerial photogrammetry. 2. The aerial photogrammetry check method according to claim 1, wherein the comparison of the corresponding points is performed by generating a square mesh on the central photograph, and finding left and right corresponding points based on the points. 3. The selection of the three aerial photographs is repeatedly performed after obtaining the three-dimensional coordinate values, and the selected photograph is shifted to the right by one from the previous selection. 3. The aerial photogrammetry checking method according to claim 1, wherein a three-dimensional coordinate value over the entire imaging target area is obtained. 4. The aerial photogrammetry checking method according to claim 1, wherein the predetermined photographing lap rate is 80%.