Visibility determination is a key requirement in a wide range of graphics algorithms. This paper introduces a new approach to the computation of volume visibility, the detection of occluded portions of space as seen from a given region. The method is conservative and classifies regions as occluded only when they are guaranteed to be invisible. It operates on a discrete representation of space and uses the opaque interior of objects as occluders. This choice of occluders facilitates their extension into adjacent opaque regions of space, in essence maximizing their size and impact. Our method efficiently detects and represents the regions of space hidden by such occluders. It is the first one to use the property that occluders can also be extended into empty space provided this space is itself occluded from the viewing volume. This proves extremely effective for computing the occlusion by a set of occluders, effectively realizing occluder fusion. An auxiliary data structure represents occlusion in the scene and can then be queried to answer volume visibility questions. We demonstrate the applicability to visibility preprocessing for real-time walkthroughs and to shadow-ray acceleration for extended light sources in ray tracing, with significant acceleration in both cases.

This paper describes the successful combination of pre‐generated and dynamically updated image‐based representations to accelerate the visualization of complex virtual environments. We introduce a new type of impostor, which has the desirable property of limiting de‐occlusion errors to a user‐specified amount. This impostor, composed of multiple layers of textured meshes, replaces the distant geometry and is much faster to draw. It captures the relevant depth complexity in the model without resorting to a complete sampling of the scene. We show that layers can be dynamically updated during visualization. This guarantees bounded scene complexity in each frame and also exploits temporal coherence to improve image quality when possible. We demonstrate the strengths of this approach in the context of city walkthroughs.

Article Free Access Share on Image-based object representation by layered impostors Author: Schaufler Gernot GUP, Johannes Kepler Universität Linz, Altenbergerstr. 69, A - 4040 Linz, Austria / EUROPE GUP, Johannes Kepler Universität Linz, Altenbergerstr. 69, A - 4040 Linz, Austria / EUROPEView Profile Authors Info & Claims VRST '98: Proceedings of the ACM symposium on Virtual reality software and technologyNovember 1998 Pages 99–104https://doi.org/10.1145/293701.293714Published:02 November 1998Publication History 5citation620DownloadsMetricsTotal Citations5Total Downloads620Last 12 Months35Last 6 weeks5 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Abstract Despite recent advances in rendering hardware, large and complex virtual environments cannot be displayed with a sufficiently highframe rate, because of limitations in the available rendering performance. This paper presents a new approach of software accelerated rendering which draws from the concepts of impostors, hierarchical scene subdivision and levels of detail. So far software optimization in real‐time rendering has merely considered individual objects. This work is actually optimizing the rendering of the whole virtual environment by implementing a three dimensional image cache. It speeds up rendering for large portions of the scene by exploiting the coherence inherent in any smooth frame sequence. The implementation of the three dimensional image cache is discussed and the savings in rendering load achievable on a suitable hardware platform are presented.