2,473 research outputs found
Extracting Skeletal Curves from 3D Scattered Data
Projet SYNTIMWe introduce a method for the construction of skeletal curves from an unorganized collection of scattered data points lying on a surface. These curves may have a tree like structure to capture branching shapes such as blood vessels. The skeletal curves can be used for different applications ranging from surface reconstruction to object recognition. As an input, the algorithm takes a set of 3D points. It returns a set of curves arranged in a tree structure. The only interaction needed is the selection of a data point which represent the root of the tree. A neighborhood graph is constructed over the set of points to compute geodesic distances between the root point and the other points. Connected level sets of the distance map are then extracted and organized in a tree structure. The centers of these levels sets constitute the skeletal curves
Unwind: Interactive Fish Straightening
The ScanAllFish project is a large-scale effort to scan all the world's
33,100 known species of fishes. It has already generated thousands of
volumetric CT scans of fish species which are available on open access
platforms such as the Open Science Framework. To achieve a scanning rate
required for a project of this magnitude, many specimens are grouped together
into a single tube and scanned all at once. The resulting data contain many
fish which are often bent and twisted to fit into the scanner. Our system,
Unwind, is a novel interactive visualization and processing tool which
extracts, unbends, and untwists volumetric images of fish with minimal user
interaction. Our approach enables scientists to interactively unwarp these
volumes to remove the undesired torque and bending using a piecewise-linear
skeleton extracted by averaging isosurfaces of a harmonic function connecting
the head and tail of each fish. The result is a volumetric dataset of a
individual, straight fish in a canonical pose defined by the marine biologist
expert user. We have developed Unwind in collaboration with a team of marine
biologists: Our system has been deployed in their labs, and is presently being
used for dataset construction, biomechanical analysis, and the generation of
figures for scientific publication
Quantitative assessment of automatic reconstructions of branching systems
ISBN 978-951-651-408-9International audienceIn this work, we propose a method to evaluate and compare different reconstruction methods from laser data using expert reconstruction and a new structural distance
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Process Planning for Solid Freeform Fabrication Based on Laser-Additive Multi-axis Deposition
This paper describes a new approach for rapid prototyping based on volumetric
skeletonization. Contrary to most of the popular techniques for Solid Freeform
Fabrication (SSF) based on 2-1/2 -axis layering as planar slices, this approach suggests
the growth of the component along all three coordinate axes. While this approach offers
many advantages in terms of the elimination of the support structures for the reduction of
the staircase effects and the elimination of various post processes for the functional parts,
this approach also offers challenges towards process planning. For various complicated
shapes it may not be possible to generate the required shape using this approach;
however, a hybrid approach which also incorporates the deposition by layers, may offer
an optimum solution. Preliminary results are based on the successful laser-based
additive deposition along multiple g-vectors. The material properties and the problems of
possible porosities are still to be investigated. Advantages, process planning,
applications, experimental results, and the challenges of this new method are the subject
of this paper.This work was financially supported by THECB (Texas Higher Education Coordinating
Board) Grants 003613-0022-1999 and 003613-0016-2001, NSF (National Science
Foundation) Grants DMI-9732848 and DMI-9809198 and by the US Department of
Education Grant P200A80806-98.Mechanical Engineerin
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