35 research outputs found
BEDRF: Bidirectional Edge Diffraction Response Function for Interactive Sound Propagation
We introduce bidirectional edge diffraction response function (BEDRF), a new
approach to model wave diffraction around edges with path tracing. The
diffraction part of the wave is expressed as an integration on path space, and
the wave-edge interaction is expressed using only the localized information
around points on the edge similar to a bidirectional scattering distribution
function (BSDF) for visual rendering. For an infinite single wedge, our model
generates the same result as the analytic solution. Our approach can be easily
integrated into interactive geometric sound propagation algorithms that use
path tracing to compute specular and diffuse reflections. Our resulting
propagation algorithm can approximate complex wave propagation phenomena
involving high-order diffraction, and is able to handle dynamic, deformable
objects and moving sources and listeners. We highlight the performance of our
approach in different scenarios to generate smooth auralization
The Ecological Water Demand of Schizothorax in Tibet Based on Habitat Area and Connectivity
Water resource regulation is convenient for humans, but also changes river hydrology and affects aquatic ecosystems. This study combined a field investigation and two-dimensional hydrodynamic model (MIKE21) to simulate the hydrodynamic distribution from 1 March to 30 April of 2008–2013 and establish the HDI (habitat depth suitability index) and HVI (habitat velocity suitability index) based on static hydraulic conditions at typical points. Additionally, by using MIKE21 to simulate the hydraulic state in the study area under 20 flow conditions from 530–1060 m3/s, and combining these states with the HCI (habitat cover type suitability index), HDI, and HVI, we simulated the WUA (weighted usable area) and habitat connectivity under different runoff regulation scenarios to study the water requirements of Schizothorax during the spawning period in the Yanni wetland. The results showed the following: (1) the suitable cover type was cobble and rock substrate, with nearby sandy land; furthermore, the suitable water depth was 0.5–1.5 m, and the suitable velocity was 0.1–0.9 m/s. (2) Using the proximity index to analyse the connectivity of suitable habitats, the range of ecological discharge determined by the WUA and connectivity was 424–1060 m/s. (3) Habitat quality was divided into three levels to detail the flow demand further. When the flow was 424–530 m3/s or 848–1060 m3/s, the WUA and connectivity generally met the requirements under natural conditions. When the flow was 530–636 m3/s or 742–848 m3/s, the WUA and connectivity were in a good state. When the flow was 636–742 m3/s, the WUA and connectivity were in the best state. This study complements existing research on the suitability of Schizothorax habitat in Tibet, and introduces the connectivity index to enrich the method for calculating ecological water demand, providing a reference for resource regulation and the protection of aquatic organisms
A Psychoacoustic Quality Criterion for Path-Traced Sound Propagation
In developing virtual acoustic environments, it is important to understand
the relationship between the computation cost and the perceptual significance
of the resultant numerical error. In this paper, we propose a quality criterion
that evaluates the error significance of path-tracing-based sound propagation
simulators. We present an analytical formula that estimates the error signal
power spectrum. With this spectrum estimation, we can use a modified Zwicker's
loudness model to calculate the relative loudness of the error signal masked by
the ideal output. Our experimental results show that the proposed criterion can
explain the human perception of simulation error in a variety of cases.Comment: 12 pages, 9 figures. To be published in IEEE TVC