Labeling and Completing Imperfect Line Drawing of Curved Objects
Dong Li-jun, Mantun Gao · Jisuanji gongcheng · 2004
The problem for recovering 3D shape from imperfect line drawing of curved objects is addressed in this paper. In section 2, the curve-surface line labeling techniques of Chakravarty's labeling scheme is extended to include invisible line. All possible configurations of imperfect line drawings of curved objects are studied and it is found that there are L junctions in imperfect line drawings of curved objects. Therefore it is necessary to take a close look at the behaviors of L junctions in imperfect line drawing of curved objects. W and Y junctions in imperfect line drawings of curved objects are the same as they are in perfect line drawing of curved objects. L junctions, however, are different because they could be degenerated from W and Y junctions. By exhausting all possible cases, it is found that the maximum number of L junctions for imperfect line drawings of curved objects is 28, and the 28 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 3, the general procedure for labeling and completing an imperfect line drawing is given; also it is shown how to utilize the line labeling and junction labeling information to predict and recover the missing line.