关键词: 轮廓线, 射线法, 坐标极值法, 位置关系, 轮廓树

Abstract: By analyzing the principle and the existing problems in the ray method and the extreme coordinate value method, the existing algorithms which determined contour direction were simplified. Then an improved algorithm on the contour line position relation was proposed combining the advantages of the ray method and the extreme coordinate method. The algorithm mainly included four parts: distinction among the internal and external contours, adjustment of the profile direction, inclusive identification of contours and the construction of a contour tree. The experimental results show that the improved algorithm can correct the problems in the existing algorithms and achieve good efficiency.

Key words: contour line, ray method, extreme coordinate value method, position relation, contour tree