An implicit and GPU based approach for solving cracks in terrain visualization

The huge storage for large terrain datasets and high resolution images have been the most important factors that influence the performance for interactive large-scale terrain rendering. To solve the problem, researchers partition a whole terrain into small tiles and utilize GPU (Graphics Processing Unit) to render them respectively. But usually the different levels of detail between adjacent tiles will induce cracks between them which will decrease the fidelity greatly. Many algorithms have presented solutions to overcome the disadvantage but haven´t achieved absolutely success either by the complexity or by the bad effect. In this paper we present an implicit and GPU-based method to overcome the traditional drawbacks. We will partition the square terrain datasets into triangular tiles and predefine the amount of the inner triangles of each tile to 2^m×2^m (m>1). Then at runtime, we force the maximum level difference of the adjacent tiles to 1. And this will connect the terrain tiles seamlessly. And in the paper we transform the DEM data into vertex texture, and store the data in GPU. And finally we use the advanced shader language HLSL to implement the operation of fetching height value. The above improvements have achieved great effect.