Real-Time Processing of Image Sources Using Binary Space Partitioning
The current state of the art of virtual reality allows a user to interact with computergenerated visual worlds and provides a high level of realism. The immersion can be increased significantly by simulating in addition the corresponding room acoustics. A correct acoustical impression is reached by the reproduction of binaural signals and at present already satisfies high demand, but for interactive systems it is mostly limited to sources located in the free field, that is, the filters used for computation are applicable for anechoic environments only. Current real-time-capable room acoustical simulations for virtual environments are mostly based on the principles of geometrical acoustics. However, these approaches do not provide an exact reproduction of a room’s sound properties under real-time conditions because of high computation demands, and they are therefore limited to the simulation of just plausible sound fields. Hence faster algorithms are required to further enhance the room acoustical simulation. A modification of the commonly known image source method is presented, which reduces the computation demands of this highly time-expensive approach remarkably. Binary space partitioning trees are used for a fast determination of audible image sources, and an efficient data structure with respect to the real-time auralization process is introduced. Thus a faster determination of the binaural room impulse response is obtained, which is essential for a real-time-capable auralization process. In addition, geometrical relations are used more efficiently to prevent the generation of redundant image sources and to increase the performance of this algorithm. Furthermore, experiments have been carried out to show the current hardware limitations for this modified image source method.
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