Precise line detection from an engineering drawing using a figure fitting method based on contours and skeletons

This paper presents a new precise line detection technique that works efficiently even for a complicated engineering drawing. Both the contours and skeletons of line regions in an image include crucial information for extracting lines precisely from a drawing. The usage of both contours and skeletons enables the following features: 1) the detected lines are hardly affected by intersecting or touching other lines; 2) the detected lines maintain the shape of the figures in the original drawing; and 3) the connectivity of lines in an image is preserved in the detected figures. Experiments on actually used drawings are discussed in order to evaluate the technique described