4,929 research outputs found
Effects of virtual acoustics on dynamic auditory distance perception
Sound propagation encompasses various acoustic phenomena including
reverberation. Current virtual acoustic methods, ranging from parametric
filters to physically-accurate solvers, can simulate reverberation with varying
degrees of fidelity. We investigate the effects of reverberant sounds generated
using different propagation algorithms on acoustic distance perception, i.e.,
how faraway humans perceive a sound source. In particular, we evaluate two
classes of methods for real-time sound propagation in dynamic scenes based on
parametric filters and ray tracing. Our study shows that the more accurate
method shows less distance compression as compared to the approximate,
filter-based method. This suggests that accurate reverberation in VR results in
a better reproduction of acoustic distances. We also quantify the levels of
distance compression introduced by different propagation methods in a virtual
environment.Comment: 8 Pages, 7 figure
Interactive real-time three-dimensional visualisation of virtual textiles
Virtual textile databases provide a cost-efficient alternative to the use of existing hardcover
sample catalogues. By taking advantage of the high performance features offered by the
latest generation of programmable graphics accelerator boards, it is possible to combine
photometric stereo methods with 3D visualisation methods to implement a virtual textile
database. In this thesis, we investigate and combine rotation invariant texture retrieval with
interactive visualisation techniques.
We use a 3D surface representation that is a generic data representation that allows us to
combine real-time interactive 3D visualisation methods with present day texture retrieval
methods. We begin by investigating the most suitable data format for the 3D surface
representation and identify relief-mapping combined with Bézier surfaces as the most
suitable 3D surface representations for our needs, and go on to describe how these
representation can be combined for real-time rendering. We then investigate ten different
methods of implementing rotation invariant texture retrieval using feature vectors. These
results show that first order statistics in the form of histogram data are very effective for
discriminating colour albedo information, while rotation invariant gradient maps are
effective for distinguishing between different types of micro-geometry using either first or
second order statistics.Engineering and physical Sciences Research (EPSRC
Target Tracking in Confined Environments with Uncertain Sensor Positions
To ensure safety in confined environments such as mines or subway tunnels, a
(wireless) sensor network can be deployed to monitor various environmental
conditions. One of its most important applications is to track personnel,
mobile equipment and vehicles. However, the state-of-the-art algorithms assume
that the positions of the sensors are perfectly known, which is not necessarily
true due to imprecise placement and/or dropping of sensors. Therefore, we
propose an automatic approach for simultaneous refinement of sensors' positions
and target tracking. We divide the considered area in a finite number of cells,
define dynamic and measurement models, and apply a discrete variant of belief
propagation which can efficiently solve this high-dimensional problem, and
handle all non-Gaussian uncertainties expected in this kind of environments.
Finally, we use ray-tracing simulation to generate an artificial mine-like
environment and generate synthetic measurement data. According to our extensive
simulation study, the proposed approach performs significantly better than
standard Bayesian target tracking and localization algorithms, and provides
robustness against outliers.Comment: IEEE Transactions on Vehicular Technology, 201
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