Suggestive Contours for Conveying Shape
Author(s): Doug DeCarlo, Adam Finkelstein, Szymon Rusinkiewicz, Anthony Santella.
Article: ACM Transactions on Graphics, Vol. 22, No. 3, pp. 848--855, July,
2003.
[BibTeX] 
Abstract:
In this paper, we describe a non-photorealistic rendering system that
conveys shape using lines. We go beyond contours and creases by
developing a new type of line to draw: the suggestive contour. Suggestive
contours are lines drawn on clearly visible parts of the surface,
where a true contour would first appear with a minimal change
in viewpoint. We provide two methods for calculating suggestive
contours, including an algorithm that finds the zero crossings of the
radial curvature. We show that suggestive contours can be drawn
consistently with true contours, because they anticipate and extend
them. We present a variety of results, arguing that these images
convey shape more effectively than contour alone.