| |
Interactive Feature Specification for Focus+Context
Visualization of Complex Simulation Data
|
|
 |
|
| Abstract:
|
Visualization of high-dimensional, large data sets, resulting from
computational simulation, is one of the most challenging fields in
scientific viualization. When visualization aims at supporting the
analysis of such data sets, feature-based approches are very useful
to reduce the amount of data which is shown at each instance of
time and guide the user to the most interesting areas of the data.
When using feature-based visualization, one of the most difficult
questions is how to extract or specify the features. This is mostly
done (semi-)automatic up to now. Especially when interactive
analysis of the data is the main goal of the visualization, tools
supporting interactive specification of features are needed.
In this paper we present a framework for flexible and interactive
specification of high-dimensional and/or complex features in
simulation data. The framework makes use of multiple, linked views
from information as well as scientific visualization and is based
on a simple and compact feature definition language (FDL). It allows
the definition of one or several features, which can be complex
and/or hierachically described by brushing multiple dimensions
(using non-binary and composite brushes). The result of the
specification is linked to all views, thereby a focus+context
style of visualization in 3D is realized. To demonstrate the usage
of the specification, as well as the linked tools, applications
from flow simulation in the automotive industry are presented.
|
| Project:
|
This work has been carried out as part of the
basic research project ``interactive visualization''
at the VRVis research center in Vienna, Austria,
which is funded by an Austrian governmental research
project called Kplus.
All data sets shown in the images on this page are courtesy of
AVL List GmbH, Graz, Austria.
|
| Paper:
|
A VRVis technical report from December 2002 captures the results of this work.
Below images on this web page are taken from this technical report.
This paper has also been published in the Proceedings of the
5th Joint IEEE TCVG - EUROGRAPHICS Symposium on
Visualization (VisSym 2003), pages 239-248, May 26-28, 2003, Grenoble, France.
|
| Video:
|
 | A video,
showing a typical analysis session with our here presented
framework is also available (DivX 5 format).
|
Results
(to retrieve an enlarged version
of the images, click on them)
|
|
Figure 1: Flexible Feature Specification:
simulation data of a catalytic converter is shown, two features have been specified
based on our feature definition language, using
the different views for interaction and visualization.
|
|
Figure 2: A feature definition language:
a sketch of its structure.
|
|
Figure 3: four examples of 2D brush
types which users found
useful during interactive analysis (catalytic
converter example, pressure [x] vs. velocity [y]):
(a) ``high velocity and high pressure'' (logical AND),
(b) ``low velocity or low pressure'' (log. OR),
(c) ``all but high vel. and high pressure'' (NOT-AND),
and (d) ``high pressure but not low velocity'' (SUB = AND-NOT).
|
|
Figure 4: Interactive feature specification
and refinement:
(a)-(c): first step: defining backflow region in a
catalytic converter (see also figure 1) in a scatterplot
view (a) by selecting negative x-flow values, direct linking
to a second scatterplot view (b) and the 3D view (c).
(d)-(f): second step: AND-refinement
with a new selection in the second scatterplot view (e), back linking
of the interaction via feedback visualization (color of points according to
newly calculated DOI values) to the first scatterplot view (d).
Now only the backflow region is selected, that exhibits general velocity above
a specified threshold (f).
|
|
Figure 5: Air-Flow around a moving car:
After loading the data set, an empty
feature set is created, and the spatial layout of the data is shown, overall velocity
information is mapped to color (green denotes low, red high velocity).
|
|
Figure 6: First step of analysis
(non-horizontal slow flow):
a tree viewer showing the current feature specification in the upper left
(interaction panel for adjusting a simple feature characteristic shown),
a scatterplot view used for feature specification in the upper right (velocity vs.
V-Velocity component), the SciViz view for f+c visualization in the lower left,
a second scatter plot for visualization of f+c distribution (X-coordinates vs. viscosity).
|
|
Figure 7: Step 2 of analysis:
AND-refinement, restricting feat. spec. to high viscosity values in the second
scatterplot view. Only features behind the car are part of focus now.
|
|
Figure 8: Step 3 of analysis:
another AND refinement, further restricting to high values of turb. kinetic energy,
performed in the tree viewer. Only parts with strong rotational component are
in focus.
|
|
Figure 9: Step 5 of analysis:
interactive probing of V-velocity reveals different behavior of vortical
structures, only downfacing parts are shown here.
|
This page
is maintained by Helmut Doleisch.
In case of questions, comments, etc., please
mailto:Doleisch@VRVis.at.
|
