A computer implemented, graph based method for determining the orientation of objects which can assume a plurality of orientations relative to a default orientation, including being rotated 90.degree. clockwise, mirrored about an X axis, or mirrored about a Y axis, where the X axis and the Y axis are...http://www.google.com.tw/patents/US6161078?utm_source=gb-gplus-share專利 US6161078 - Efficient method for solving systems of discrete rotation and reflection constraints
