Abstract.
A virtual scene (or synthetic environment) is an integrated set of data elements that describe a defined geographical region. It must contain a consistent and correlated description of the full physical environment (terrain, features and 3-D objects). The modeling of virtual scenes is inherently a geometrical problem and can be solved based on computational geometry algorithms and data structures.
For large virtual scenes, including extended geographical regions, with dense features and objects, the volume of data required for database representation has a huge size, which affects both storage requirements and visualization time. It is possible to manage data complexity by adopting a multiresolution representation of the dataset, based on data simplification.
The approximated representation of volume data for a given resolution level is controlled by the value of the maximum error allowed and by boundary conditions for the spatial continuity across levels of detail. In our work, we combined incremental Delaunay triangulation with the control of maximum error of the approximated model. In this way, different resolutions of the approximated model can be obtain for different error tolerances, and all these constitute the multiresolution representation of the three-dimensional dataset.
The representation and visualization of large synthetic environments was studied and experimented on a Silicon Graphics multiprocessor, Onyx, with four MIPS R10000 processors and Infinite Reality graphic accelerator, under IRIX 6.4 operating system. The synthetic environment consists in the geographical area of our country, over 6 latitude x 10 longitude degrees.