A Fresh Perspective

”Painting is an activity, and the artist will therefore tend to see what he paints rather than to paint what he sees.” E.H. Gombrich. While general trends in computer graphics continue to drive towards more photorealistic imagery, increasing attention is also being devoted to painterly renderings of computer generated scenes. Whereas artists using traditional media almost always deviate from the confines of a precise linear perspective view, digital artists struggle to transcend the standard pin-hole camera model in generating an envisioned image of a three dimensional scene. More specifically, a key limitation of existing camera models is that they inhibit the artistic exploration and understanding of a subject, which is essential for expressing it successfully. Past experiments with non-linear perspectives have primarily focused on abstract mathematical camera models for raytracing, which are both noninteractive and provide the artist with little control over seeing what he wants to see. We address this limitation with a cohesive, interactive approach for exploring nonlinear perspective projections. The approach consists of a new camera model and a toolbox of interactive local and global controls for a number of properties, including regions of interest, distortion, and spatial relationship. Furthermore, the approach is incremental, allowing non-linear perspective views of a scene to be built gradually by blending and compositing multiple linear perspectives. In addition to artistic non-photorealistic rendering, our approach has interesting applications in conceptual design and scientific visualization.