Top–Down View–Dependent Terrain Triangulation using the Octagon Metric

In this paper, we introduce the octagon metric as a useful distance metric for the interactive visualization of large–scale terrain data. Based on recursive bisection triangle meshes, this metric automatically ensures valid distance–dependent triangulations without cracks or T–junctions. We will show how the octagon metric can be used for view–dependent refinement at little computational cost and with no additional storage requirements. It can easily be combined with a suitable geometric error metric to extract and render adaptive view–dependent terrain meshes in an output–sensitive way. We show the performance of the whole system, which is straightforward to implement, and its advantages over previous approaches in several examples.