A Line-Tracker

Interpretation of line drawings is largely dependent on the quality of line-recognition, because lines form the building blocks of these types of drawings. Because of its importance, considerable effort has been put in line-recognition. There are two main approaches to line recognition, line-detection and line-tracking. Line-detection is a parallel proces of global-image operations such as segmentation, edge-detection and clustering, in principle using little a priori information where to find the line. The difficulty here is to assure connectivity in the detected line-segments (see [Jonk95]). Line-tracking is a sequential process starting from an a priori located point on the line. The difficultu here is reach the end of the line. Line-tracking may use an adaptive model of the profile, hence provides more information to the line-recognition step. When lines are of very poor quality global-image techniques are very costly, ineffective or give rise to a large number of false hits (observe figure 1 for an example). In such a case line trackers are the preferred method.