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We present an interactive spherical terrain rendering system employing a hierarchical subdivision of the HEALPix coordinate system using quadtrees. Compared to other parameterizations, the scheme avoids singularities and allows for efficient fusion of mixed-resolution digital elevation models and imagery. A Level-of-Detail heuristic is used to guarantee both high performance and visual fidelity. Unified treatment of DEM and imagery data is achieved by performing the HEALPix projection within a GPU shader. The system is applied to the exploration of Mars, using both MOLA (NASA) and HRSC (German Aerospace Center) data sets.
Westerteiger et al. (2012) studied this question.