Cut and Paint

Abstract

Surface selection operations by a user are fundamental for many applications and a standard tool in mesh editing software. Unfortunately, defining a selection is only straightforward if the region is visible and on a convex model. Concave surfaces can exhibit self-occlusions, which require using multiple camera positions to obtain unobstructed views. The process thus becomes iterative and
cumbersome. Our novel approach enables selections to lie under occlusions and even on the backside of objects and for arbitrary depth complexity at interactive rates. We rely on a user-drawn curve in screen space, which is projected onto the mesh and analyzed with respect to visibility to guarantee a continuous path on the surface. Our occlusion-aware surface-processing method enables a number
of applications in an easy way. As examples, we show continuous painting on the surface, selecting regions for texturing, creating illustrative cutaways from nested models and animate them.