不完整立体线图的补线技术研究

不完整线图中的L型节点是完整线图中W和Y型节点的退化。基于画出隐藏线的完整线图标记方法，建立了不完整线图中L型节点与完整线图中W和Y型节点的对应关系。提出了不完整线图的标记和补线方法，结合算例论述了不完整线图的标记和补线过程。从不完整线图获得了合理的完整线图及其标记。

A New Method for Labeling and Completing Imperfect Line Drawings

Almost all line labeling techniques require perfect line drawing as their input. Experience indicates, however, that it is unreasonable to expect perfect contours from segmented images; lines are often missing due to poor lighting and noise. Line drawings often are imperfect. The problem for recovering 3D shape from imperfect line drawing was addressed in this paper. A new theory and method is proposed for labeling the two dimensional imperfect line drawing of a three dimensional object with trihedral vertices. We studied all possible configurations of imperfect line drawings and found that there are L junctions in imperfect line drawings. Therefore it is necessary to take a close look at the behaviors of L junctions in imperfect line drawing. W and Y junctions in imperfect line drawings are the same as they are in perfect line drawing. L junctions, however, are different because they could be degenerated from W and Y junctions. By exhausting all possible cases, we found that the maximum number of L junctions for imperfect line drawings is 36, and the 36 L junctions and their corresponding W and Y junctions from which these L junctions are degenerated are illustrated; they are shown in Table 1.In section 2, the general procedure for labeling and completing an imperfect line drawing is given; we also show how to utilize the line labeling and junction labeling information to predict and recover the missing line.