An efficient continuous level of detail model for foliage

Outdoor scenes require vegetation to make them look realistic. Current hardware cannot afford real-time rendering of these scenes because of the large number of polygons. Multiresolution modelling has been successfully presented as a solution to the problem of efficient manipulation of highly detailed polygonal surfaces. This article describes a new continuous multiresolution hardware-oriented model that can represent tree foliage with different levels of detail. The multiresolution model presented in this paper, Level of Detail Foliage, takes advantage of the programmable rendering pipelines nowadays available in most video cards. The geometry of the foliage is divided into a number of clusters, in some of which the detail can change while the rest of the clusters remain unaltered. This division of the foliage remarkably diminishes the number of vertices sent to the graphics system because only the information of the changed clusters are updated. The independent clusters condition a data structure that makes the time required for visualisation of the foliage more efficient. Here we present the data structure and the retrieval algorithms, which favour the extraction of an appropriate level of detail for rendering.