3D gradient enhancement

Abstract

Enhancement can exaggerate visual details in both image processing and 3D rendering. In this paper, we adapt the gradient enhancement technique from image processing to 3D rendering through differentiating the rendering result with respect to the image space coordinates under point lighting. In this way, we can achieve 3D enhancement taking into account the gradient of geometry, projection transform, visibility and highlight. We also propose a tunable shape descriptor for users to achieve rendering results in different enhancement extent. Moreover, we extend this method to the environment lighting with some simplifications. Finally, we demonstrate that our method can handle the grazing angle area and the edges of sharp slope better than the previous method due to the gradient of the projection transform.