Geometry Reduction in Room Acoustics Modeling

This thesis represents a method for reducing the geometry of complex room models to make it possible to model their acoustics in real-time. It is shown that reducing geometry can vastly decrease the modeling time. This conclusion is supported by the experimental results. The previous work on geometric model simplification is surveyed extensively. The re-duction algorithms are grouped into decimation algorithms and surface reconstruction algorithms. The decimation algorithms are categorized into vertex removal, vertex clustering, edge collapsing, and triangle removal algorithms. The surface reconstruction algorithms include re-meshing and volumetric approaches. The main contribution of this thesis is a method for reducing geometric models for acoustics modeling. It consists of two steps: topology simplification and geometry reduction. Two approaches are suggested for the topology simplification, one based on a regular density grid and another based on an octree. There are also two algorithms for the geometry reduction both of which are trying to merge small coplanar triangles into large polygons. The results of the reduction method are evaluated using the acoustical parameters. Also the performance of the reduction algorithm is analyzed. The experiments show that the algorithm preserves spatial properties, measured by the reverberation time, relatively well. The algorithm can produce coarsest level approximations in real-time, but more accurate approximations require significantly longer times for computation.