Analyzing pre-fetching in large-scale visual simulation

This paper studies pre-fetching mechanisms that support walkthroughs of virtual environments with overall data sizes exceeding current core memory capacities of PCs. Specifically, it formulates the pre-fetch problem using motion characteristics of the viewer, the data density of the virtual environment, and the data transfer capability of the disk. It further analyzes two fundamental classes of pre-fetching schemes, which are classified by their uses of certain pre-assigned spatial or temporal thresholds. The analysis is supported and verified by experiments on terrain walkthroughs performed on different configurations of PCs. An interesting finding is the understanding of how the terrain data density supportable is a function of the duration of time allocated to disk-level pre-fetching. On the whole, this paper provides a methodology for analyzing prefetch performance as well as presents insights instrumental in the design and optimization of out-of-core walkthrough systems.