The aim of the rapid world modeling project is to implement a system to visualize the topography of the entire world on consumer-level hardware. This presents a significant problem in terms of both storage requirements and rendering speed. This paper presents the ‘Tiled Quad Tree’, a technique and format for the storage of digital terrain models, to work as part of an integrated system for the visualization of global terrain data. We show how this format efficiently stores and compresses elevation data, in a way that allows the data to be read very rapidly from hard disk or similar storage medium, to facilitate real-time rendering. The results of compressing several distinct data sets are presented.