Accurate Reflections Through a Z-Buffered Environment Map

A new algorithm for computing accurate reflections with an environment map is presented. This new algorithm keeps the z-buffers originally calculated to obtain the map and uses them to find the best approximator to the real reflected point. It performs a linear search in the plane defined by the reflected vector and the position of the reflective surface. For each vector in this plane, the algorithm calculates how close to the real reflection point it is, and keeps only the one that approximates the reflected position best. The resulting images are identical to those computed with other methods (i.e. recursive Ray Tracing). The model offers the posibility of computing all the reflections with just one environment map per scene. The running time of the current implementation of the model is ten to fifty times slower than the implementation of the old reflection map models, but the expected final running time is only five times slower. The limitations of the new model are analysed and a solution is provided.