Patent ID: 6285805
Filing Date: 2001-09-04
Classification: G06T,Y10S

Abstract:
A system for determining a closest point on a shape to a query point comprising:one or more memories for storing one or more geometric model portions, the geometric model portions having a plurality of line segments, each of the line segments being between a first and a second endpoint, wherein the line segments and end points are connected to form a shape including one or more parameters; andone or more central processing units (CPU's) for executing:a multiresolution process that creates one or more models of the shape, the one or more models having a hierarchy of resolutions, wherein each model comprises one or more model line segments approximating one or more of the line segments and wherein each model line segment is associated with an error;a distance process that for every model line segment determines a distance between a closest point on one or more of the model line segments and a query point, the distance representing one or more of the parameters, the distance process further determining an upper bound and a lower bound of an envelope enclosing the segment, the closest point being within the envelope, the upper bound representing an upper limit of the parameter in the envelope determined by an upper error of the respective model containing the model line segment and the lower bound representing a lower limit of the parameter in the envelope determined by a lower error of the respective model, wherein the upper bound and the lower bound of the envelope are parallel to each other or converging to each other; anda priority process that orders the model line segments according to their respective lower bounds if a maximum error for every one of the model line segments is less than a threshold, the priority process selecting a smallest distance as a minimum distance between the query point and the shape.