VMV13

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https://diglib.eg.org/handle/10.2312/1017

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Browsing VMV13 by Subject "Computational Geometry and Object Modeling"

Now showing 1 - 4 of 4
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    Fine-Scale Editing of Continuous Volumes using Adaptive Surfaces
    (The Eurographics Association, 2013) Ruhl, Kai; Wenger, Stephan; Franke, Dennis; Saretzki, Julius; Magnor, Marcus; Michael Bronstein and Jean Favre and Kai Hormann
    Many fields of science such as astronomy and astrophysics require the visualization and editing of smooth, continuous volume data. However, current high-level approaches to volume editing concentrate on segmentable volume data prevalent in medical or engineering contexts, and therefore rely on the presence of well-defined 3D surface layers. Editing arbitrary volumes, on the other hand, is currently only possible using low-level approaches based on the rather unintuitive direct manipulation of axis-aligned slices. In this paper, we present a technique to add or modify fine-scale structures within astronomical nebulae based on adaptive drawing surfaces that enable 2Dimage- like editing approaches. Our results look more natural and have been produced in a much shorter time than previously possible with axis-aligned slice editing.
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    Level of Detail for Real-Time Volumetric Terrain Rendering
    (The Eurographics Association, 2013) Scholz, Manuel; Bender, Jan; Dachsbacher, Carsten; Michael Bronstein and Jean Favre and Kai Hormann
    Terrain rendering is an important component of many GIS applications and simulators. Most methods rely on heightmap-based terrain which is simple to acquire and handle, but has limited capabilities for modeling features like caves, steep cliffs, or overhangs. In contrast, volumetric terrain models, e.g. based on isosurfaces can represent arbitrary topology. In this paper, we present a fast, practical and GPU-friendly level of detail algorithm for large scale volumetric terrain that is specifically designed for real-time rendering applications. Our algorithm is based on a longest edge bisection (LEB) scheme. The resulting tetrahedral cells are subdivided into four hexahedra, which form the domain for a subsequent isosurface extraction step. The algorithm can be used with arbitrary volumetric models such as signed distance fields, which can be generated from triangle meshes or discrete volume data sets. In contrast to previous methods our algorithm does not require any stitching between detail levels. It generates crack free surfaces with a good triangle quality. Furthermore, we efficiently extract the geometry at runtime and require no preprocessing, which allows us to render infinite procedural content with low memory consumption.
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    A Thin Shell Approach to the Registration of Implicit Surfaces
    (The Eurographics Association, 2013) Iglesias, Jose A.; Berkels, Benjamin; Rumpf, Martin; Scherzer, Otmar; Michael Bronstein and Jean Favre and Kai Hormann
    Frequently, one aims at the co-registration of geometries described implicitly by images as level sets. This paper proposes a novel shape sensitive approach for the matching of such implicit surfaces. Motivated by physical models of elastic shells a variational approach is proposed, which distinguishes two different types of energy contributions: a membrane energy measuring the rate of tangential distortion when deforming the reference surface into the template surface, and a bending energy reflecting the required amount of bending. The variational model is formulated via a narrow band approach. The built in tangential distortion energy leads to a suitable equidistribution of deformed length and area elements, under the optimal matching deformation, whereas the minimization of the bending energy fosters a proper matching of shape features such as crests, valleys or bumps. In the implementation, a spatial discretization via finite elements, a nonlinear conjugate gradient scheme with a Sobolev metric, and a cascadic multilevel optimization strategy are used. The features of the proposed method are discussed via applications both for synthetic and realistic examples.
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    A Tracking Approach for the Skeletonization of Tubular Parts of 3D Shapes
    (The Eurographics Association, 2013) Garro, Valeria; Giachetti, Andrea; Michael Bronstein and Jean Favre and Kai Hormann
    In this paper we propose a new simple and efficient method to characterize shapes by segmenting their elongated parts and characterizing them with their centerlines. We call it Tubular Section Tracking, because it consists of slicing the interested volume along different directions, tracking centroids of the extracted sections with approximately constant centroid position, area and eccentricity and refining the extracted lines with a post processing step removing bad branches and centering, joining and extending the relevant ones. We show that, even using just a few slicing directions (in some cases even just three perpendicular directions), the method is able to obtain good results, approximately pose independent and that the extracted lines can be more informative on the relevant feature of the objects than the classical skeletal lines extracted as subsets of the medial axis. Estimated lines can be used to segment shapes into meaningful parts and compute useful parameters (e.g. length, diameters).