Real-time global illumination rendering for mesostructure surface based on gradient map

Rendering global illumination for objects with mesostructure surfaces is a time-consuming task and cannot presently be applied to interactive graphics. This paper presents a real-time rendering method, based on a mesostructure height gradient map (MHGM), to exhibit lighting effects on meso-scale detail level in dynamic environments. This paper approximates global illumination by using a lighting model that includes specific characteristics: Incident ambient light, direct light, and a single bounce indirect light. In order to compute these three components in real time, this paper introduces the MHGM to create local apex sets, with which an adaptive method for calculating ambient occlusion is proposed. In direct lighting, the nearest local apex profile of the incident rays is to be found and presented as a mesostructure shadow algorithm, which can generate the shadow of meso-scale details. The color of the points enclosed by the local apexes is also sampled to estimate a single bounce indirect light. This approach runs entirely on the graphics hardware and uses deferred shading and the graphics pipeline to accelerate computation. High quality results, which can render meso-scale details with global illumination even for low-resolution geometric models, are achieved. Moreover, this approach fully supports dynamic scenes and deformable objects.