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Simplification of Scene Geometry for Sound Propagation Sachin Patil Existing Sound Propagation Approaches : Limitations Several methods available for sound propagation
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Simplification of Scene Geometry for Sound Propagation Sachin Patil
Existing Sound Propagation Approaches : Limitations • Several methods available for sound propagation • Too slow for real-time sound propagation taking into account the increasing scene complexity, dynamic environments and multiplicity of sources/listeners • Acceleration techniques : Culling structures like BSP-trees, SIMD hacks, GPU implementations are no longer sufficient • Most VR systems do not allocate a large chunk of resources for handling sound • Solve the sound propagation problem for simplified scenes • Introduces the need for defining a metric for measuring acoustic fidelity
Commercial acoustic simulation software ‘Glue Surface’ option provided by ODEON (www.odeon.dk) for manipulating CAD models for acoustic simulations
It’s a jungle out there Taxonomy of Geometry Reduction techniques [1]
Criterion for geometry reduction for acoustics • Absorption coefficients for polygonal faced in the scene : controlling error while blending and simplification • Rough surfaces account for diffuse reflection and scattering • Volume and total absorption area must be preserved as various parameters such as reverberation time heavily dependent on these criteria • For handling reflections correctly, surface normals must be preserved as accurately as possible • Features comparable to the wavelength of the sound must be preserved
Issues • Tradeoffs between: • Cost of simplification and sound propagation • Offline simplification versus real-time simplification • Ease of implementation of the proposed approach • Local reduction of features versus global simplification
Project goals • Given a simplified scene, how different is the sound ‘quality’ as compared to the original • Could be statistical, acoustic metrics or perceptual user studies • Planning to use an industry standard benchmark for acoustic measurements such as CATT, ODEON • Given such a metric, how and by how much can one simplify a given scene geometry without perceptual differences in ‘quality’ • Progressive simplification and LOD: Providing frame-rate guarantees given the resources available for sound simulation and propagation
Project roadmap and deliverables • Use existing libraries to simplify scene geometry and carry out initial tests using CATT to determine an error metric for measuring acoustic fidelity • Study existing methods for geometry simplification and choose an existing approach/ propose a novel approach to solve this problem • Integration with existing work : Sound propagation using ray-frusta tracing / adaptive rectangular decomposition
References • Geometry Reduction in Room Acoustics Modeling: Samuel Siltanen • Significant Facet Retrieval for Real-Time 3D Sound Rendering in Complex Virtual Environments: C.Joslin, M.Thalmann • Instant Sound Scattering: N.Tsingos, C.Dachsbacher, S.Lefebvre, M.Dellepiane • Interactions of Model Detail Level and Scattering Coefficients in Room Acoustic Computer Simulation: L.Wang, J.Rathsam, J.Rindel