Suggestive contours for conveying shape

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.