A hybrid backward-forward method for interactive reflections

We propose a two phase hybrid reflection rendering method based on approximating the reflected rays with a set of simple cameras modeled as continuous 3-ray cameras. In the first, "backward", phase, the view volume of each simple camera is intersected with a hierarchical subdivision of the scene to find the geometry it encompasses. In the second, "forward", phase the geometry is projected with the simple camera. Since the shape and topology of reflected triangles is complex, point based rendering is adopted to reconstruct the reflection. The hybrid method is efficient since it combines advantages of backward and forward techniques: there are two orders of magnitude fewer simple cameras than reflected rays, the hierarchical scene subdivision implements fast view volume culling for each of the simple cameras, and the reflection piece corresponding to each simple camera is computed efficiently in feed-forward fashion.