Multiresolution Visualization and Compression of Global Topographic Data

We present a multiresolution model for surfaces which is able to handle large–scale global topographic data. It is based on a hierarchical decomposition of the sphere by a recursive bisection triangulation in geographic coordinates. Error indicators allow the representation of the data at various levels of detail and enable data compression by local omission of data values. The resulting hierarchical triangulation is stored using a bit code of the underlying binary tree and, additionally, relative pointers which allow an adaptive tree traversal. This way, it is possible to work directly on the compressed data. We show that significant compression rates can be obtained already for small threshold values. In a visualization application, adaptive triangulations which consist of hundreds of thousands of shaded triangles are extracted and drawn at interactive rates. Classification: 65D05, 65N50, 65Y25, 68U05