A new approach to the 'hidden line' problem

Jones, Cliff B.

doi:10.1093/comjnl/14.3.232

Cited by 56 publications

(19 citation statements)

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“…We incrementally compute beams starting from a source by traversing the cell-face and face-edge adjacency graph of a polyhedral cell complex, as in [19,1,12,13,39] (see Figure 3). Starting in the cell containing the source with a beam representing the entire cell, we iteratively visit adjacent cells in priority order, considering different permutations of transmission, specular reflection, and diffraction resulting from the faces and edges on the boundary of the "current" cell.…”

Section: Beam Construction and Tracingmentioning

confidence: 99%

Modeling acoustics in virtual environments using the uniform theory of diffraction

Tsingos

Ngan

Carlbom

2001

Proceedings of the 28th Annual Conference on Computer Graphics and Interactive Techniques

165

152

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Realistic modeling of reverberant sound in 3D virtual worlds provides users with important cues for localizing sound sources and understanding spatial properties of the environment. Unfortunately, current geometric acoustic modeling systems do not accurately simulate reverberant sound. Instead, they model only direct transmission and specular reflection, while diffraction is either ignored or modeled through statistical approximation. However, diffraction is important for correct interpretation of acoustic environments, especially when the direct path between sound source and receiver is occluded.The Uniform Theory of Diffraction (UTD) extends geometrical acoustics with diffraction phenomena: illuminated edges become secondary sources of diffracted rays that in turn may propagate through the environment. In this paper, we propose an efficient way for computing the acoustical effect of diffraction paths using the UTD for deriving secondary diffracted rays and associated diffraction coefficients. Our main contributions are: 1) a beam tracing method for enumerating sequences of diffracting edges efficiently and without aliasing in densely occluded polyhedral environments; 2) a practical approximation to the simulated sound field in which diffraction is considered only in shadow regions; and 3) a real-time auralization system demonstrating that diffraction dramatically improves the quality of spatialized sound in virtual environments.

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Section: Beam Construction and Tracingmentioning

confidence: 99%

Modeling acoustics in virtual environments using the uniform theory of diffraction

Tsingos

Ngan

Carlbom

2001

Proceedings of the 28th Annual Conference on Computer Graphics and Interactive Techniques

165

152

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“…Occlusion culling techniques were first proposed by Jones [Jon71] and Clark [Cla76]. Airey et al [ARB90] and Teller et al [TS91,Tel92] were the first to actually perform visibility preprocessing in architectural environments.…”

Section: Previous Workmentioning

confidence: 99%

Conservative visibility preprocessing using extended projections

Durand

Drettakis

Thollot

et al. 2000

Proceedings of the 27th Annual Conference on Computer Graphics and Interactive Techniques - SIGGRAPH '00

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Visualization of very complex scenes can be significantly accelerated using occlusion culling. In this paper we present a visibility preprocessing method which efficiently computes potentially visible geometry for volumetric viewing cells. We introduce novel extended projection operators, which permits efficient and conservative occlusion culling with respect to all viewpoints within a cell, and takes into account the combined occlusion effect of multiple occluders. We use extended projection of occluders onto a set of projection planes to create extended occlusion maps; we show how to efficiently test occludees against these occlusion maps to determine occlusion with respect to the entire cell. We also present an improved projection operator for certain specific but important configurations. An important advantage of our approach is that we can re-project extended projections onto a series of projection planes (via an occlusion sweep), and accumulate occlusion information from multiple blockers. This new approach allows the creation of effective occlusion maps for previously hard-to-treat scenes such as leaves of trees in a forest. Graphics hardware is used to accelerate both the extended projection and reprojection operations. We present a complete implementation demonstrating significant speedup with respect to view-frustum culling only, without the computational overhead of on-line occlusion culling.

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“…For walkthroughs of urban area or complex architectures, occlusion culling is imperative since most objects are hidden behind the occluders with respect to the current viewpoint. Probably the earliest work in this area is by Jones in 1971 [23].…”

Section: Introductionmentioning

confidence: 99%

The global occlusion map

Wei

Bao

Peng

et al. 2002

Proceedings of the ACM Symposium on Virtual Reality Software and Technology

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Occlusion culling is an important technique to speed up the rendering process for walkthroughs in a complex environment. In this paper, we present a new approach for occlusion culling with respect to a view cell. A compact representation, the Global Occlusion Map (GOM), is proposed for storing the global visibility information of general 3D models with respect to the view cell. The GOM provides a collection of Directional Visibility Barriers (DVB), which are virtual occluding planes aligned with the main axes of the world coordinates that act as occluders to reject invisible objects lying behind them in every direction from a view cell. Since the GOM is a two-dimensional array, its size is bounded, depending only on the number of the sampled viewing directions. Furthermore, it is easy to conservatively compress the GOM by treating it as a depth image. Due to the axial orientations of the DVBs, both the computational and storage costs for occlusion culling based on the GOM is minimized. Our implementation shows the Global Occlusion Map is effective and efficient in urban walkthrough applications.

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A new approach to the 'hidden line' problem

Cited by 56 publications

References 0 publications

Modeling acoustics in virtual environments using the uniform theory of diffraction

Modeling acoustics in virtual environments using the uniform theory of diffraction

Conservative visibility preprocessing using extended projections

The global occlusion map

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