2,676 research outputs found
An Octree-Based Approach towards Efficient Variational Range Data Fusion
Volume-based reconstruction is usually expensive both in terms of memory
consumption and runtime. Especially for sparse geometric structures, volumetric
representations produce a huge computational overhead. We present an efficient
way to fuse range data via a variational Octree-based minimization approach by
taking the actual range data geometry into account. We transform the data into
Octree-based truncated signed distance fields and show how the optimization can
be conducted on the newly created structures. The main challenge is to uphold
speed and a low memory footprint without sacrificing the solutions' accuracy
during optimization. We explain how to dynamically adjust the optimizer's
geometric structure via joining/splitting of Octree nodes and how to define the
operators. We evaluate on various datasets and outline the suitability in terms
of performance and geometric accuracy.Comment: BMVC 201
Center-of-Mass Properties of the Exciton in Quantum Wells
We present high-quality numerical calculations of the exciton center-of-mass
dispersion for GaAs/AlGaAs quantum wells of widths in the range 2-20 nm. The
k.p-coupling of the heavy- and light-hole bands is fully taken into account. An
optimized center-of-mass transformation enhances numerical convergence. We
derive an easy-to-use semi-analytical expression for the exciton groundstate
mass from an ansatz for the exciton wavefunction at finite momentum. It is
checked against the numerical results and found to give very good results. We
also show multiband calculations of the exciton groundstate dispersion using a
finite-differences scheme in real space, which can be applied to rather general
heterostructures.Comment: 19 pages, 12 figures included, to be published in Phys. Rev.
Adaptive coarse-to-fine quantization for optimizing rate-distortion of progressive mesh compression
International audienceWe propose a new connectivity-based progressivecompression approach for triangle meshes. The keyidea is to adapt the quantization precision to the resolutionof each intermediate mesh so as to optimizethe rate-distortion trade-off. This adaptation is automaticallydetermined during the encoding processand the overhead is efficiently encoded using geometricalprediction techniques. We also introducean optimization of the geometry coding by usinga bijective discrete rotation. Results show that ourapproach delivers a better rate-distortion behaviorthan both connectivity-based and geometry-basedcompression state of the art method
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