Real-time Piecewise Perspective Projections

This paper presents an approach to real-time rendering of non-planar projections with a single center and straight projection rays. Its goal is to provide optimal and consistent image quality. It operates entirely in object space to remove the need for image resampling. In contrast to most other object-space approaches, it does not evaluate non-linear functions on the GPU, but approximates the projection itself by a set of perspective projection pieces. Within each piece, graphics hardware can provide optimal image quality. The result is a coherent and crisp rendering. Procedural textures and stylization effects greatly benefit from our method as they usually rely on screen-space operations. The real-time implementation runs entirely on GPU. It replicates input primitives on demand and renders them into all relevant projection pieces. The method is independent of the input mesh density and is not restricted to static meshes. Thus, it is well suited for interactive applications. We demonstrate it for an analytic and a freely designed projection.