Three-dimensional measurement apparatus, processing method, and non-transitory computer-readable storage medium

Abstract

A three-dimensional measurement apparatus selects points corresponding to geometric features of a three-dimensional shape model of a target object, projects a plurality of selected points corresponding to the geometric features onto a range image based on approximate values indicating the position and orientation of the target object and imaging parameters at the time of imaging of the range image, searches regions of predetermined ranges respectively from the plurality of projected points for geometric features on the range image which correspond to the geometric features of the three-dimensional shape model, and associates these geometric features with each other. The apparatus then calculates the position and orientation of the target object using differences of distances on a three-dimensional space between the geometric features of the three-dimensional shape model and those on the range image, which are associated with each other.

1 . A three-dimensional measurement apparatus comprising;
 image acquisition means for acquiring a range image in which pixels represent distances from a target object;   approximate value acquisition means for acquiring approximate values indicating a position and an orientation of the target object;   selection means for selecting points corresponding to geometric features of a three-dimensional shape model of the target object;   projection means for projecting a plurality of points corresponding to the geometric features selected by said selection means onto the range image based on the approximate values indicating the position and the orientation of the target object and imaging parameters at the time of imaging of the range image,   search means for searching regions of predetermined ranges respectively from the plurality of projected points for geometric features on the range image which correspond to the geometric features of the three-dimensional shape model, and associating the geometric features with each other; and   position/orientation calculation means for calculating a position and an orientation of the target object using differences of distances on a three-dimensional space between the geometric features of the three-dimensional shape model and the geometric features on the range image, which are associated with each other by said search means.   
     
     
         2 . The apparatus according to  claim 1 , characterized in that said image acquisition means further acquires a two-dimensional image obtained by capturing the target object,
 said projection means projects a plurality of points corresponding to the geometric features selected by said selection means onto the range image and the two-dimensional image based on the approximate values indicating the position and the orientation of the target object and imaging parameters at the time of imaging of the range image,   said search means searches regions of predetermined ranges respectively from the plurality of projected points for geometric features on the range image and the two-dimensional image which correspond to the geometric features of the three-dimensional shape model, and associates the geometric features with each other, and   said position/orientation calculation means calculates the position and the orientation of the target object using differences of distances on the three-dimensional space between the geometric features of the three-dimensional shape model and the geometric features on the range image and the two-dimensional image, which are associated with each other by said search means.   
     
     
         3 . The apparatus according to  claim 1 , characterized in that said search means compares a normal direction to a geometric feature of the three-dimensional shape model at a point selected by said selection means with a normal direction to the geometric feature detected from the predetermined range of the projected point on the range image, and when the two normal directions are different beyond a predetermined value, said search means skips the association processing of the geometric features. 
     
     
         4 . The apparatus according to  claim 2 , characterized in that the two-dimensional image is captured from the same viewpoint as the range image, and
 said search means detects edges of the target object from the two-dimensional image as the geometric features of the two-dimensional image, and skips association processing between an edge which is not included in the geometric features on the range image and a corresponding geometric feature of the three-dimensional shape model upon execution of the association processing between the detected edges and the geometric features of the three-dimensional shape model.   
     
     
         5 . The apparatus according to  claim 1 , characterized in that the geometric features of the three-dimensional shape model are expressed by points or line segments. 
     
     
         6 . A processing method for a three-dimensional measurement apparatus for calculating a position and an orientation of a target object, characterized by comprising:
 a step of acquiring a range image in which pixels represent distances from a target object;   a step of acquiring approximate values indicating a position and an orientation of the target object;   a step of selecting points corresponding to geometric features of a three-dimensional shape model of the target object;   a step of projecting a plurality of selected points corresponding to the geometric features onto the range image based on the approximate values indicating the position and the orientation of the target object and imaging parameters at the time of imaging of the range image;   a step of searching regions of predetermined ranges respectively from the plurality of projected points for geometric features on the range image which correspond to the geometric features of the three-dimensional shape model, and associating the geometric features with each other; and   a step of calculating a position and an orientation of the target object using differences of distances on a three-dimensional space between the geometric features of the three-dimensional shape model and the geometric features on the range image, which are associated with each other.   
     
     
         7 . A non-transitory computer-readable storage medium storing a computer program for controlling a computer incorporated in a three-dimensional measurement apparatus for calculating a position and an orientation of a target object, to function as:
 image acquisition means for acquiring a range image in which pixels represent distances from a target object;   approximate value acquisition means for acquiring approximate values indicating a position and an orientation of the target object;   selection means for selecting points corresponding to geometric features of a three-dimensional shape model of the target object;   projection means for projecting a plurality of points corresponding to the geometric features selected by said selection means onto the range image based on the approximate values indicating the position and the orientation of the target object and imaging parameters at the time of imaging of the range image,   search means for searching regions of predetermined ranges respectively from the plurality of projected points for geometric features on the range image which correspond to the geometric features of the three-dimensional shape model, and associating the geometric features with each other; and   position/orientation calculation means for calculating a position and an orientation of the target object using differences of distances on a three-dimensional space between the geometric features of the three-dimensional shape model and the geometric features on the range image, which are associated with each other by said search means.