Multi-resolution terrain rendering using summed-area tables

摘要

Due to the fundamental weaknesses of level-of-detail (LOD) control and rich details in the Geometry Clipmaps, we propose a multi-resolution terrain rendering algorithm that utilizes summed-area tables (SATs) [1] to facilitate the rendering of terrain with better geometric and shading details. First, our algorithm introduces a novel geometric error bound on the screen-based terrain rendering approach that juggles low rendering throughput and better LOD control. Geometric errors are estimated in real-time from SATs, enabling error-bounded geometry clipmap. Second, we utilize Spherical Gaussian (SG) functions to approximate lighting and bidirectional reflection distribution functions (BRDFs), and efficiently calculate outgoing radiance with self-occlusions of the terrain. SATs are utilized to enable the mipmapping of visibility and normal maps. We demonstrate the improvements of our method with experiments on accuracy and efficiency.(c) 2021 Elsevier Ltd. All rights reserved.