中文摘要：

利用Zmap模型在切削层上构造物体区域的行程编码，根据行程编码的连通关系链接节点形成边界，通过确定边界之间的包容关系构造边界描述树，从而得到切削区域的拓扑结构．该算法简单、效率高，能自动识别轮廓和岛屿，并已在实际中得到很好的应用．

英文摘要：

Compound surfaces are approximated by Zmap model to demarcate cutting areas against the remaining untouched zone, resulting in a binary image of each cutting layer with black pixels representing the cutting areas and white pixels showing the remaining zone. Run-length coding is under taken to describe the configuration of black image in each cutting layer sequentially linking the terminal nodes according to the A boundary-tracing algorithm extracts boundaries by connectivity information of runs. The formed loops are sorted and arranged into a tree structure to represent the topological correlation of the cutting areas in a cutting layer, The presented method is simple and effective. It can recognize contours and islands, Experimental machining results demonstrate the feasibility of this algorithm.