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GVU Technical Report
Number: GIT-GVU-05-18
Title:
Subdomain Aware Contour Trees and Contour Evolution in Time-Dependent Scalar Fields
Authors:
Andrzej Szymczak
Abstract:
For time-dependent scalar fields, one is often interested
in topology changes of contours in time. In this paper, we focus
on describing how contours split and merge over a certain
time interval. Rather than attempting to describe all individual
contour splitting and merging events, we focus on
the simpler and therefore more tractable in practice problem:
describing and querying the cumulative effect of the
splitting and merging events over a user-specified time interval.
Using our system one can, for example, find all contours
at time tº that continue to two contours at time t¹
without hitting the boundary of the domain. For any such
contour, there has to be a bifurcation happening to it somewhere
between the two times, but, in addition to that, many
other events may possibly happen without changing the cumulative
outcome (e.g. merging with several contours born
after tº or splitting off several contours that disappear before
t¹).
Our approach is flexible enough to enable other types of
queries, if they can be cast as counting queries for numbers
of connected components of intersections of contours
with certain simply connected domains. Examples of such
queries include finding contours with large life spans, contours
avoiding certain subset of the domain over a given
time interval or contours that continue to two at a later time
and then merge back to one some time later.
Experimental results show that our method can handle
large 3D (2 space dimensions plus time) and 4D (3D+time)
datasets. Both preprocessing and query algorithms can easily
be parallelized.
Keywords:
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