ConTesse: Accurate Occluding Contours for Subdivision Surfaces

TL;DR

This paper introduces ConTesse, a novel method for accurately computing and validating occluding contours of subdivision surfaces, enabling improved visibility rendering in non-photorealistic visualization.

Contribution

It presents new theoretical conditions for contour validity and an algorithm to generate contours that satisfy these conditions for subdivision surfaces.

Findings

The method guarantees valid contour visibility conditions.

It produces contours suitable for standard rendering algorithms.

Applicable to any triangle mesh as a subdivision surface base.

Abstract

This paper proposes a method for computing the visible occluding contours of subdivision surfaces. The paper first introduces new theory for contour visibility of smooth surfaces. Necessary and sufficient conditions are introduced for when a sampled occluding contour is valid, that is, when it may be assigned consistent visibility. Previous methods do not guarantee these conditions, which helps explain why smooth contour visibility has been such a challenging problem in the past. The paper then proposes an algorithm that, given a subdivision surface, finds sampled contours satisfying these conditions, and then generates a new triangle mesh matching the given occluding contours. The contours of the output triangle mesh may then be rendered with standard non-photorealistic rendering algorithms, using the mesh for visibility computation. The method can be applied to any triangle mesh, by treating it as the base mesh of a subdivision surface.