NPR Lenses: Interactive Tools for Non-photorealistic Line Drawings

NPR Lenses is an interactive technique for producing expressive non-photorealistic renderings. It provides an intuitive visual interaction tool for illustrators, allowing them to seamlessly apply a large variety of emphasis techniques. Advantages of 3D scene manipulation are combined with the capabilities of viewer-aligned lenses by inserting 2D lens controls into the 3D rendering pipeline. By using lenses that are spatially explicit and constrained we enable object-independent adjustments in 3D. Regions of emphasis can be easily created by adjusting lens parameters and any combination of line style, type, shape, and position of computer-generated lines. NPR Lenses support the creation of effects similar to those found in many existing hand-drawn illustrations and allow creative freedom through interactive control at the same time.