Algebraic Smooth Occluding Contours

Ryan Capouellez, Jiacheng Dai, Aaron Hertzmann, Denis Zorin

Abstract: Computing occluding contours is a key step in 3D non-photorealistic rendering, but producing smooth contours with consistent visibility has been a notoriously-challenging open problem. This paper describes the first general-purpose smooth surface construction for which the occluding contours can be computed in closed form. Given an input mesh and camera viewpoint, we show how to approximate the mesh with a G1 piecewise-quadratic surface, for which the occluding contours are piecewise-rational curves in image-space. We show that this method produces smooth contours with consistent visibility much more efficiently than the state-of-the-art.