[Infolix] gt combi du lix, vendredi janvier 11h, Jarek Rossignac

Chers collegues,

nous avons les plaisir d´accueillir au IX le prof. Jarek Rossignac, qui
donnera un exposé demain (vendredi 20) a´ 11h (salle des séminaires du
LIX).
Vous trouverez le titre et résumé ci-dessous.

A bientot

Luca Castelli Aleardi

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Mesh parsimony: Towards compact formats for processing and transmitting
triangulations

Jarek Rossignac
School of Interactive Computing, Georgia Institute of Technology
http://www.gvu.gatech.edu/~jarek/

Modern representations of 3D shapes in Engineering, Scientific, Medical,
and Entertainment domains are based on triangulations. The constant
increase in the fidelity—and hence complexity—of these models increases
storage cost and hence adversely impacts transmission and processing
performance. To address this problem, we discuss compact formats
for transmitting and processing triangulations. On the practical side, we
review the Corner-Table (CT)—a representation for triangle meshes, where
the connectivity is encoded as 13 rpv (references per vertex)—and the
associated standard sets of random, mesh-traversal corner-operators. Its
simplicity and compactness makes it a prime choice for teaching and
implementing mesh-processing algorithms. We also discuss its VOT extension
to tetrahedral meshes, which requires storing about 48 rpv, and the
associated mesh-traversal wedge-operators. Then, we review the popular
triangle-mesh compression, Edgebreaker, which requires about 2 bpv (bits
per vertex) and can be implemented with a few lines of code, and discuss
some improvements and extensions to tetrahedral meshes, including
TetStreamer, which requires only about 10 bpv. Finally, we discuss recent
advances in compact mesh-representations that support the corner-operators
and wedge-operators at constant cost. These include SOT (which halves the
storage requirements of CT and VOT), SQuad for triangle meshes (which
requires 4 rpv), and LR (which orders the vertices around a nearly
Hamiltonian cycle and requires only about 1.6 rpv). On the theoretical
side, we cast the recent approaches as special cases of the catalogue
approach of Castelli-Aleardi&Devillers, investigate the role of
re-orderings and the interplay between compression, streaming, and
random-access support, and seek to extract the essential information that
is captured in the connectivity of a triangle mesh.

The talk is based on joint work with U. Bischoff, T. Gurung, P. Lindstrom,
M. Luffel, and A. Szymczak and other colleagues.