Computer Aided Civil and Infrastructure Engineering

https://cg.informatik.uni-freiburg.de/intern/seminar/surfaceReconstruction_survey%20of%20marching%20cubes.pdf

A survey of the marching cubes algorithm

L E Reichl 1980 Austin: University of Texas Press xii + 709 pp price $29.95 I can thoroughly recommend this book and congratulate the author for having brought together so many aspects of statistical physics in a comprehensible manner. The subject matter is modern; all the recent developments such as stochastic theory, theories of quantum fluids and critical phenomena, nonlinear chemical physics and hydrodynamics are included and yet each topic is built up from its foundations.

A Modern Course in Statistical Physics

This paper introduces a novel, region-growing algorithm for the fast surface patch segmentation of three-dimensional point clouds of urban environments. The proposed algorithm is composed of two stages based on a coarse-to-fine concept. First, a region-growing step is performed on an octree-based voxelized representation of the input point cloud to extract major (coarse) segments. The output is then passed through a refinement process. As part of this, there are two competing factors related to voxel size selection. To balance the constraints, an adaptive octree is created in two stages. Empirical studies on real terrestrial and airborne laser scanning data for complex buildings and an urban setting show the proposed approach to be at least an order of magnitude faster when compared to a conventional region growing method and able to incorporate semantic-based feature criteria, while achieving precision, recall, and fitness scores of at least 75% and as much as 95%.

Octree-based region growing for point cloud segmentation

We show that contour trees can be computed in all dimensions by a simple algorithm that merges two trees. Our algorithm extends, simplifies, and improves work of Tarasov and Vyalyi and of van Kreveld et al.

Computing contour trees in all dimensions

The contour tree, an abstraction of a scalar field that encodes the nesting relationships of isosurfaces, can be used to accelerate isosurface extraction, to identify important isovalues for volume-rendering transfer functions, and to guide exploratory visualization through a flexible isosurface interface. Many real-world data sets produce unmanageably large contour trees which require meaningful simplification. We define local geometric measures for individual contours, such as surface area and contained volume, and provide an algorithm to compute these measures in a contour tree. We then use these geometric measures to simplify the contour trees, suppressing minor topological features of the data. We combine this with a flexible isosurface interface to allow users to explore individual contours of a dataset interactively.

/pdf/simplifying-flexible-isosurfaces-using-local-geometric-1ol5hxpaxm.pdf

Simplifying Flexible Isosurfaces Using Local Geometric Measures

Topology provides a foundation for the development of mathematically sound tools for processing and exploration of scalar fields. Existing topology-based methods can be used to identify interesting features in volumetric data sets, to find seed sets for accelerated isosurface extraction, or to treat individual connected components as distinct entities for isosurfacing or interval volume rendering. We describe a framework for direct volume rendering based on segmenting a volume into regions of equivalent contour topology and applying separate transfer functions to each region. Each region corresponds to a branch of a hierarchical contour tree decomposition, and a separate transfer function can be defined for it. The novel contributions of our work are: 1) a volume rendering framework and interface where a unique transfer function can be assigned to each subvolume corresponding to a branch of the contour tree, 2) a runtime method for adjusting data values to reflect contour tree simplifications, 3) an efficient way of mapping a spatial location into the contour tree to determine the applicable transfer function, and 4) an algorithm for hardware-accelerated direct volume rendering that visualizes the contour tree-based segmentation at interactive frame rates using graphics processing units (GPUs) that support loops and conditional branches in fragment programs

/pdf/topology-controlled-volume-rendering-2v3bswxil8.pdf

Hamish Carr

Papers

Computing contour trees in all dimensions

Computing contour trees in all dimensions

Simplifying Flexible Isosurfaces Using Local Geometric Measures

Topology-Controlled Volume Rendering

Topology-controlled volume rendering