JPH077453B2 - Fixed point removal method for three-dimensional measurement by spherical mapping - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to a three-dimensional measurement method for measuring a three-dimensional image using a spherical map, and more particularly to a fixed point removal method for three-dimensional measurement for removing a fixed point that is not useful for measurement. For the purpose of speeding up the removal process, the process of extracting the mapping points by spherical projection and spherical mapping of the stereoscopic image while moving the shooting point, and the process of removing the fixed points in these extracted mapping points. In the three-dimensional measurement method by the spherical map including the three-dimensional measurement of the stereoscopic image based on the mapping point information after the fixed point removal, the fixed point removal process includes a projection point on the spherical surface in the moving direction of the shooting point. It is configured to include the process of removing the equator having the poles and the mapping points near the equator as preprocessing.

[Industrial application field]

The present invention relates to a three-dimensional measurement method for measuring a three-dimensional image using a spherical map, and more particularly to a fixed point removal method for three-dimensional measurement that removes a fixed point that is not useful for measurement.

For example, when making a robot work in a place where human entry is dangerous, such as a nuclear reactor, it is necessary to measure the distance to the target and its posture in order to operate the target with the robot manipulator. However, it is necessary that such measurement calculations can be performed in real time at high speed.

[Conventional technology]

In order to perform such stereoscopic measurement, a camera provided on the robot side performs spherical projection of an object, and the projected image is image-processed to obtain various three-dimensional information such as the presence / absence of a line segment, its direction and distance. Techniques for extracting are known, for example, those proposed in JP-A-60-218183 or JP-A-61-258414 (JP-A-63-113782).

A method of measuring the position of a line segment in a three-dimensional space using a spherical map will be described. First, as shown in FIG. 6, the line segment L is spherically projected onto a spherical surface to obtain an arc L ′, and this arc L Draw a great circle (corresponding to the equator when each point is the North Pole) centered on each point on the sphere. As a result, a mapping point S where the great circles of the stereoscopic image intersect is obtained.

Next, as shown in FIG. 7, the photographing position of the camera is moved in an arbitrary linear direction V by a constant interval, and a line segment is photographed at each moving point to extract the above-mentioned S points. When a plurality of mapping points S ₁ , S ₂ and S ₃ thus obtained are further spherically mapped and a great circle corresponding to each S point is drawn, a mapping point SS point of the present invention is obtained as an intersection of these great circles. . This SS point serves as information indicating the direction of the line segment L.

In this way, the line segment L is photographed while moving the camera to collect information on the S point, the SS point, and the like, and based on these, the three-dimensional measurement calculation of the direction and distance of the line segment is performed. In addition,
For details of these, the above-mentioned publication can be referred to.

[Problems to be Solved by the Invention]

The mapping points extracted by the above method also include mapping points unnecessary for three-dimensional measurement calculation. For example, it is a mapping point of an image at a position far away from the camera (for example, a background in the room), and such an image is unnecessary for robot work. Also, the line segment that faces the same direction as the moving direction of the camera does not move on the sphere even if the camera is moved to perform the time-series mapping. It can be said that these are unnecessary because they do not contribute to direction measurement.

Therefore, processing for removing these fixed points is performed prior to the three-dimensional measurement calculation, and various methods have been proposed as this processing method.

However, these fixed point removal processes are performed for each of the extracted mapping points, and the processing time is generally long. For this reason, if the fixed point removal processing is performed on all the extracted mapping points, the time required to complete the entire processing becomes very long, and the real-time processing required for robot work or the like cannot be realized.

Therefore, an object of the present invention is to speed up the fixed point removal processing.

[Means for solving the problem]

FIG. 1 is a principle diagram according to the present invention. The fixed point removal method for three-dimensional measurement by spherical mapping according to the present invention is a process of extracting a mapping point S by performing spherical projection and spherical mapping of a stereoscopic image while moving the photographing point (step S1), and these extracted points. In a three-dimensional measurement method using a spherical map, including a process of removing fixed points in the mapping points (step S2) and a process of three-dimensionally measuring a stereoscopic image based on the mapping point information after the removal of the fixed points (step S3). , The fixed point removal process (step S2)
The process (step S4) of removing the equator 1 having the projection point Vo on the spherical surface in the shooting point movement direction (V) as a pole and the mapping point near the equator (step S4) is included as preprocessing.

[Action]

Some mapping points are known to be fixed points if the direction of camera movement is known. Such mapping points may be discarded as pre-processing without performing time-consuming fixed point removal processing.

That is, as shown in FIG. 2, assuming that the moving direction of the camera is V, the line segment L parallel to this direction V has its mapping points S ₁ , S ₂ , S even if the camera is moved. The position of ₃ … is immovable. This mapping point is the projection point on the sphere in the moving direction V.
It is always on the equator with Vo as the pole. Therefore, the mapping points on the equator with Vo as the pole are removed as a pre-processing of the fixed point removal processing regardless of the density. This preprocessing can be performed in a short time because the coordinate information is simply used. As a result, the number of mapping points for which time-consuming fixed point removal processing is performed is reduced, so that the overall processing time is shortened and the processing speed can be increased.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a flow chart of an embodiment according to the present invention, which is performed as a pre-process prior to the fixed point removal process calculation performed for each mapping point.

Now, assume that the coordinate system of the spherical camera is as shown in FIG. Here, the longitude is represented by α and the latitude is represented by β, which are quantized to 0 to 1023 and 0 to 608, respectively. Further, it is assumed that the moving direction of the camera is V and V is parallel to the Y-axis direction. FIG. 5 is a diagram in which the coordinate system of FIG. 4 is expanded to a plane.

Here, it is assumed that there exists a line segment parallel to the plane including the X axis and the direction V, and the point S, which is a spherical mapping of this line segment, has the direction V
It is always on the equator with the projected point Vo on the sphere of as the pole. Therefore, even if the photographing position of the camera is moved, this point S does not move. Therefore, the point S on the equator with Vo as the pole is removed regardless of the concentration. This removal processing can be easily performed by searching for and removing the longitude 256 or 768 of the plane coordinates in FIG. 5 and the S point at a position in the vicinity thereof.

As the processing procedure, the coordinates (αs, βs) of the S point are input (step S10), and it is determined whether or not the coordinates (αs, βs) are at the equator with Vo as the pole or in the vicinity of the equator (step
S11). If it is near the equator, this S point data is removed (step S12). If it is not output, it is output as it is, and then the fixed point removal processing calculation is performed.

〔The invention's effect〕

According to the present invention, since unnecessary fixed points can be removed prior to the fixed point removal processing calculation, the time required for the fixed point removal processing calculation can be shortened as a whole, and high-speed 3D measurement can be achieved. Can be realized.

[Brief description of drawings]

 1 and 2 are explanatory views of the principle according to the present invention, FIG. 3 is a flow chart showing a processing procedure of an embodiment according to the present invention, FIG. 4 is an explanatory view of a coordinate system of a spherical camera, and FIG. FIG. 4 is a diagram in which the spherical coordinates in FIG. 4 are expanded on a plane, FIG. 6 is a diagram for explaining an S point extraction method, and FIG. 7 is a diagram for explaining an SS point extraction method. In the figure, L ... Line segment, S ... Map ... V ... Camera moving direction l ... Equator with Vo as the pole

Claims (1)

[Claims] 1. A step (S1) of extracting a mapping point (S) by spherical projection and spherical mapping of a three-dimensional image while moving a shooting point, and a step of removing fixed points from these extracted mapping points. In the three-dimensional measurement method by the spherical mapping including the step (S2) and the step of performing the three-dimensional measurement of the stereoscopic image based on the mapping point information after the removal of the fixed point, the fixed point removal step (step S2) Is the process of removing the equator having the projection point on the sphere in the moving direction (V) of the shooting point as a pole and the mapping points near the equator (step S
Fixed point removal method for three-dimensional measurement by spherical mapping, characterized in that 4) is included as preprocessing.