Balancing Fidelity and Performance in Virtual Walkthrough

Abstract

In a virtual reality (VR) system, users expect both high visual quality as well as a high constant frame rate when they interact with the system (walkthrough). However, realizing these two requirements for very large virtual environments (VE) that cannot fit in the main memory has not been adequately addressed in the literature. In this paper, we present a novel access method, called ViSA (Visibility and Spatial data Access method) that, given a region of the current view point, returns the set of 3D objects of VEs that are visible from, as well as those that are in, the region. Ideally, these 3D objects will be loaded into memory and rendered during walkthrough. However, to balance the visual fidelity (showing all visible objects) and constant high frame rate, we dynamically determine the number and set of objects that are to be loaded based on the current memory size and frame rate. In order to minimize 110 cost, we propose an optimized search technique. We have implemented the ViSA structure in a prototype walkthrough system and our experiments show that it can provide quality visual fidelity with an acceptable constant real time frame rate.KeywordsVisual FidelityVisibility and Spatial DataVirtual EnvironmentSecondary Storage Indexing