Position and orientation calibration method and apparatus

Abstract

A position and orientation measuring apparatus calculates a difference between an image feature of a two-dimensional image of an object and a projected image of a three-dimensional model in a stored position and orientation of the object projected on the two-dimensional image. The position and orientation measuring apparatus further calculates a difference between three-dimensional coordinate information and a three-dimensional model in the stored position and orientation of the object. The position and orientation measuring apparatus then converts a dimension of the first difference and/or the second difference to cause the first difference and the second difference to have an equivalent dimension and corrects the stored position and orientation.

1 . An apparatus comprising:
 an approximate coarse position and orientation obtain unit configured to obtain an approximate position and orientation of an object;   a two-dimensional image obtain unit configured to obtain a two-dimensional image of the object;   a three-dimensional image obtain unit configured to obtain three-dimensional coordinate information of a surface of the object;   a holding unit configured to hold a three-dimensional model of the object;   a detecting unit configured to detect an image feature from the two-dimensional image;   a first associating unit configured to associate the detected image feature with a feature of the held three-dimensional model based on the approximate position and orientation of the object;   a second associating unit configured to associate the three-dimensional coordinate information of a surface of the object with the feature of the held three-dimensional model based on the approximate position and orientation of the object;   and a deriving unit configured to derive a position and orientation of the object based on an associated result and the approximate position and orientation of the object.   
     
     
         2 . The apparatus according to  claim 1 , wherein the three-dimensional model is CAD model. 
     
     
         3 . The apparatus according to  claim 1 , wherein the three-dimensional coordinate information is obtained from a range image including the object. 
     
     
         4 . The apparatus according to  claim 1 , further comprises:
 a calculating unit configured to calculate a difference between the associated image feature and the feature of the held three-dimensional model:   a second calculating unit configured to calculate a second difference between the associated three-dimensional coordinate information and the feature of the held three-dimensional model; and   the deriving unit derives the position and orientation of the object based on the associated result and the approximate position and orientation of the object by correcting the approximate position and orientation so as to reduce the first difference and the second difference.   
     
     
         5 . The apparatus according to  claim 1 , wherein the first associating unit associates the detected image feature with a feature of the held three-dimensional model by projecting the coarse position and orientation of the object onto the two-dimensional image. 
     
     
         6 . The apparatus according to  claim 1 , wherein the deriving unit derives the position and orientation of the object by repeating an associating process of the first associating unit and an associating process of the second associating unit. 
     
     
         7 . The apparatus according to  claim 1 , wherein the two-dimensional image is a captured image of the object. 
     
     
         8 . The apparatus according to  claim 1 , wherein the three-dimensional coordinate information includes three-dimensional coordinates of a point group on a surface of the object acquired from a range image. 
     
     
         9 . The apparatus according to  claim 1 , wherein the image feature includes a feature point or an edge. 
     
     
         10 . A method comprising:
 obtaining a coarse position and orientation of an object;   obtaining a two-dimensional image of the object;   obtaining three-dimensional coordinate information of a surface of the object;   detecting an image feature from the two-dimensional image;   associating the detected image feature with a feature of a three-dimensional model held by a holding unit based on the approximate position and orientation of the object;   associating the three-dimensional coordinate information of a surface of the object with the feature of the held three-dimensional model based on the coarse position and orientation of the object; and   deriving a position and orientation of the object based on an associated result and the approximate position and orientation of the object.   
     
     
         11 . A non-transitory computer-readable-storage medium storing computer-executable instructions for executing processing includes:
 computer-executable instructions for obtaining an approximate position and orientation of an object;   computer-executable instructions for obtaining a two-dimensional image of the object;   computer-executable instructions for obtaining three-dimensional coordinate information of a surface of the object;   computer-executable instructions for detecting an image feature from the two-dimensional image;   computer-executable instructions for associating the detected image feature with a feature of a three-dimensional model held by a holding unit based on the approximate position and orientation of the object;   computer-executable instructions for associating the three-dimensional coordinate information of a surface of the object with the feature of the held three-dimensional model based on the approximate position and orientation of the object; and   computer-executable instructions for deriving a position and orientation of the object based on an associated result and the approximate position and orientation of the object.