Flexible Clipmaps for Managing Growing Textures

Previous work on large image data sets has evolved techniques for handling representations of these data that cache textures of arbitrary, but fixed, size in a limited amount of physical memory for rendering in realtime. In these approaches the texture data is usually pre-processed and arranged, for instance in a geometryindependent texture clipmap. New technologies in the area of remote sensing generate aerial images in realtime at a high rate in a patchwork-like pattern, and new images may replace previously captured image data. These patchwork-like image data can be used to create a growing texture which is dynamic in the sense that it may be updated in parts and grow in extension in the course of time. For such growing textures, current clipmap techniques are not appropriate. In this paper we introduce the Flexible Clipmap, a technique for incrementally generating a clipmap from a large virtual texture of dynamically changing content and extent. Our technique makes use of a tile-based clipmap approach and a common spatial indexing data structure to provide access to very large growing textures. We present an evaluation of our technique in the context of a remote sensing application which demands real-time rendering of growing texture data.