34-Issue 2
https://diglib.eg.org:443/handle/10.2312/12150
EG 2015 - Conference Issue2024-03-19T08:25:46ZEUROGRAPHICS 2015: CGF 34-2 Frontmatter
https://diglib.eg.org:443/handle/10.1111/cgf12601
EUROGRAPHICS 2015: CGF 34-2 Frontmatter
Olga Sorkine-Hornung; Michael Wimmer
2015-01-01T00:00:00ZOptimal Spline Approximation via l0-Minimization
https://diglib.eg.org:443/handle/10.1111/cgf12589
Optimal Spline Approximation via l0-Minimization
Brandt, Christopher; Seidel, Hans-Peter; Hildebrandt, Klaus
Olga Sorkine-Hornung and Michael Wimmer
Splines are part of the standard toolbox for the approximation of functions and curves in Rd. Still, the problem of finding the spline that best approximates an input function or curve is ill-posed, since in general this yields a ''spline'' with an infinite number of segments. The problem can be regularized by adding a penalty term for the number of spline segments. We show how this idea can be formulated as an 0-regularized quadratic problem. This gives us a notion of optimal approximating splines that depend on one parameter, which weights the approximation error against the number of segments. We detail this concept for different types of splines including B-splines and composite Bézier curves. Based on the latest development in the field of sparse approximation, we devise a solver for the resulting minimization problems and show applications to spline approximation of planar and space curves and to spline conversion of motion capture data.
2015-01-01T00:00:00ZStatics Aware Grid Shells
https://diglib.eg.org:443/handle/10.1111/cgf12590
Statics Aware Grid Shells
Pietroni, Nico; Tonelli, Davide; Puppo, Enrico; Froli, Maurizio; Scopigno, Roberto; Cignoni, Paolo
Olga Sorkine-Hornung and Michael Wimmer
We introduce a framework for the generation of polygonal grid-shell architectural structures, whose topology is designed in order to excel in static performances. We start from the analysis of stress on the input surface and we use the resulting tensor field to induce an anisotropic non-Euclidean metric over it. This metric is derived by studying the relation between the stress tensor over a continuous shell and the optimal shape of polygons in a corresponding grid-shell. Polygonal meshes with uniform density and isotropic cells under this metric exhibit variable density and anisotropy in Euclidean space, thus achieving a better distribution of the strain energy over their elements. Meshes are further optimized taking into account symmetry and regularity of cells to improve aesthetics. We experiment with quad meshes and hex-dominant meshes, demonstrating that our grid-shells achieve better static performances than state-of-the-art grid-shells.
2015-01-01T00:00:00ZGeneral and Robust Error Estimation and Reconstruction for Monte Carlo Rendering
https://diglib.eg.org:443/handle/10.1111/cgf12587
General and Robust Error Estimation and Reconstruction for Monte Carlo Rendering
Bauszat, Pablo; Eisemann, Martin; Eisemann, Elmar; Magnor, Marcus
Olga Sorkine-Hornung and Michael Wimmer
Adaptive filtering techniques have proven successful in handling non-uniform noise in Monte-Carlo rendering approaches. A recent trend is to choose an optimal filter per pixel from a selection of non spatially-varying filters. Nonetheless, the best filter choice is difficult to predict in the absence of a reference rendering. Our approach relies on the observation that the reconstruction error is locally smooth for a given filter. Hence, we propose to construct a dense error prediction from a small set of sparse but robust estimates. The filter selection is then formulated as a non-local optimization problem, which we solve via graph cuts, to avoid visual artifacts due to inconsistent filter choices. Our approach does not impose any restrictions on the used filters, outperforms previous state-of-the-art techniques and provides an extensible framework for future reconstruction techniques.
2015-01-01T00:00:00Z