ABSTRACT
The level artists created lofted roads (the racing tracks) using a plugin for 3D Studio Max and stitched them into the terrain mesh. Each lofted road was itself a height field-a quad strip with two triangles per quad. When stitched into the terrain, the road was required to conform to the shape of the terrain. This meant that any terrain vertices covered by a road needed to be inherited by the road geometry, and the texture coordinates for the lofted road had to be interpolated to generate texture coordinates for the inherited vertices. This process is tedious and time consuming, especially given that the artists iterated frequently, making modifications to the decimated terrain and to the roads. We wanted a tool that would automate this process. The second portion of this article is a discussion about the tools to support the automation. They involve constrained Delaunay triangulation for the automated stitching and some detailed programming to handle
the inheritance of vertices and texture coordinate generation. As always, technical problems occurred during the development, and artists are fond of requesting new features. The article contains some discussion about these problems and features. For a good survey of decimation algorithms, including those useful for level of detail, see [Luebke et al. 03]. Methods for decimating terrain may be found at The Virtual Terrain Project [Collaborators 10].
