Semi-automatic stencil creation through error minimization

Abstract

Creating physical stencils from 3D meshes is a unique rendering challenge that has not been previously addressed. The task is a problem of two competing goals: forming a single, well-connected and stable stencil sheet, while simultaneously limiting the error introduced by pieces of bridging material. Under these conflicting goals, it can often be difficult to create visually pleasing stencils from complicated imagery by hand. Even for well-behaved images, expressive stencils can be time-consuming to craft manually.We present a method for generating expressive stencils from polygonal meshes or images. In our system, users provide input geometry and can adjust desired view, lighting conditions, line thickness, and bridge preferences to achieve their final desired stencil. The stencil creation algorithm makes use of multiple metrics to measure the appropriateness of connections between unstable stencil regions. These metrics describe local features to help minimize the distortion of the abstracted image caused by stabilizing bridges. The algorithm also uses local statistics to choose a best fit connection that maintains both structural integrity and local shape information. We demonstrate our algorithm on physical media including construction paper and sheet metal.