Sketch Based Construction and Rendering of Implicit Models

We present an implicit modeling system as a tool for creating a wide range of aesthetic models. Because of their ability to form blends and produce both organic shapes as well as man-made objects, implicit surfaces are a good medium for artists seeking new ways to experiment with 3D modeling. Implicit models can be created using our sketch-based modeling tool Shapeshop and also by using a procedural interface. Further, we exploit the differential properties of implicit surfaces to explore new techniques for rendering hierarchical, skeletal implicit models in several pen and ink styles. Our method extracts and stylizes silhouette strokes, lines following local shape features, such as those caused by CSG junctions and abrupt blends, and short interior marks to reveal basic form. In this approach we use a particle system as a basis for the stroke extraction method.