Reliable GPU-Based Methods and Algorithms of Implementation Dynamic Relief Shadows in Virtual Environment Systems

Abstract

The paper considers the task of real-time rendering of dynamic relief shadows based on ray casting using origin relief data - detailed height map. The solution proposed is based on looking for shadow rays - sun rays, whose tracks on height map are passed through heights occluding the light. GPU-based methods and algorithms for extracting such rays using an accelerating data structure - a mipmap of maximum and minimum relief heights are developed. This structure provides an effective acceleration of shadow rays extraction by skipping long sections of sun ray tracks that are not involved in relief shadowing. In algorithms developed precise traversing such a data structure is implemented, as well as texture filtering is taking into account, which allows the formation of "torn" shadow edges to be prevented. The solution created was implemented in software complex and a number of comparative shadow visualization tests was conducted. The results of the research can be used in virtual environment systems, video simulators, scientific visualization, educational applications, etc.