VisLunch/Fall2009

Coming up next friday

- Delaunay Methods for Approximating Geometric Domains

The Delaunay triangulation is used extensively for representing geometric
domains. In this talk, I consider the use of the Delaunay triangulation for
approximating two different domains. First, I present an algorithm, DelIso,
for building Delaunay meshes to approximate smooth surfaces defined by the
isosurfaces of volume datasets. DelIso employs a two stage algorithm which
discards the need to maintain the full 3D Delaunay triangulation in the second
stage. Implementation results have shown that by using this optimization we
can obtain a 2-3 times speedup over its one stage counterpart.

The second domain investigated is piecewise smooth complexes (PSCs). One of
the limitations of past meshing algorithms is that they could only be applied
to either smooth surfaces or polyhedral domains. PSCs are a more general
class where the shape is modeled as a collection of smooth patches that can
meet sharp corners as well as non-manifolds. We have designed DelPSC, an
algorithm to build Delaunay meshes that approximate PSCs. DelPSC was designed
to be easily implementable, removing the need for many of the expensive
computations that previously made Delaunay meshing for PSCs impractical. Its
meshing strategy employs a novel protection scheme to preserve sharp features
throughout the refinement. We can also guarantee that by reducing a single
scale parameter, the correct topology is achieved for the output mesh. The
approach used in DelPSC allows for meshing a wide variety of objects such as
non-smooth CAD parts and non-manifold objects.

- Speaker: Joshua A. Levine (Ohio State University), http://www.cse.ohio-state.edu/~levinej/

- Where: Conference Room 3760

- When: Friday noon (09/04)

---

Coming up next next friday

- Topological Analysis of 2D Steady Vector Fields

Vector fields arise widely in various
engineering applications. Topological analysis extracts
the qualitative information (i.e. structure) of a provided
vector field. The topology of a vector field consists of a
set of features of interest and their connectivity which
forms a graph called topological graph. This graph
segments the data domain into a number of sub-regions in
each of which the flow behavior possesses the same nature.
Therefore, topological analysis provides an efficient
means for the engineers to investigate the behaviors of
their data. In this talk, I will focus on the topology of
2D steady vector fields which is well defined. I will
briefly explain why engineers are interested in certain
features in 2D steday vector fields. Also, I will review
some techniques of extracting these features and
constructing the topological graphs with the focus on my
PhD work including ECG and MCG computation. To learn more
about what they are, please come to the talk.

- Speaker: Guoning Chen (SCI), http://oregonstate.edu/~cheng/

- Where: Conference Room 3760

- When: Friday noon (09/11)

---

August 28, 2009

- Topology-based systems for data analysis and visualization

Topological techniques have become popular for the analysis of scalar
functions, for example, for automatic feature detection and
extraction. In this informal talk, I will present an overview of the
various software solutions we are developing to solve data analysis
and visualization problems. Some topological methods currently in
development at SCI utilize Reeb graphs, Morse-Smale complexes and
Jacobi sets. Some motivation and basic background for these techniques
will be presented in the talk. In particular, the main focus of the
talk will be covering the breadth of techniques that are currently
being developed here, and an overview of the state of the software
implementations.

- Speaker: Attila Gyulassy (SCI), http://idav.ucdavis.edu/~jediati/

- Where: Conference Room 3760

- When: Friday noon (08/28)

---

Open Discussion and Semester Planning

A common practice for VisLunch is to use some of its
sessions as a mean to let people know about the work
of the new people around: new faculties, new post docs,
new PhD. students . As there are lots of new faces
around, we hope to schedule some of these presentations
in this session.

- Summer Internships

Hurrah! It's back to school time!

PhD. Students are strongly invited to schedule a VisLunch talk (~ 30 minutes)
to present the work they accomplished during their summer internship.

- IEEE VIS talks

Wow! SCI rocked once again at IEEE VIS this year!

If you're the presenter of an accepted VIS paper, please let
us know and we'll schedule a session for you so you can practice your talk.

This semester Julien Tierny and Attila Gyulassy will be responsible
for organizing the VisLunch sessions. Please feel free to contact them
for any question regarding VisLunch or for scheduling a talk:

Julien Tierny
Attila Gyulassy
Room: 4660
Phone: 585-3911
jtierny@sci.utah.edu, aggyulassy@ucdavis.edu

Information regarding the VisLunch sessions will posted on this wiki page (http://www.vistrails.org/index.php/VisLunch/Fall2009)

---