Deferred blending: image composition for single-pass point rendering

Abstract

In this paper, we propose novel GPU accelerated algorithms for interactive point-based rendering (PBR) and high-quality shading of transparent point surfaces. By introducing the concept of deferred blending we are able to formulate the smooth point interpolation problem as an image compositing post-processing task. Consequently, our new PBR algorithm does not suffer from an extra visibilitysplatting pre-render pass, for conservative e–z-buffer visibility culling, as this is eventually performed together with the smooth point interpolation during image compositing. Moreover, this new deferred blending concept enables hardware accelerated transparent PBR with combined effects of multi-layer transparency, refraction, specular reflection, and per-fragment shading. Deferred blending is based on a separation of the point data into not self-overlapping minimal independent groups, a multi-target rendering pass and an image compositing post-processing stage. We present different grouping algorithms for off-line and on-line processing. For basic opaque surface rendering and simple transparency effects, our novel algorithm only needs a single geometry rendering pass. For high-quality transparent image synthesis one extra rendering pass is sufficient. Besides transparency, per-fragment reflective and refractive multi-layer
effects (e.g. environment mapping) are supported in our algorithm.