Meteorological Data Analysis
Description
These Images show 3D weather radar measurements (data provided by D. Meetschen,
Dept. of Meteorology, Univ. Bonn) of a heavy rainfall event during May 3rd,
2001 in northwestern Germany. The rainfall is visualized by 20 transparent
isosurfaces with low opacity and color ranging from white to blue. The radar
information is displayed on top of a 50m digital elevation model of the
measurement area (courtesy of SFB350) color shaded according to elevation value.
The whole system is in implemented in a multiresolution framework. This
allows a fast interaction with the data (radar and terrain) by providing
good approximations of the data at highly reduced triangle counts. This allows
a interactive handling of the data at several frames per second. For the
final images the full resolution is used which takes several seconds to
render on a normal PC.
Since the radar data is given in a weird coordinate system
(conical/cylindrical), direct volume rendering techniques, such as ray casting
or splatting are difficult to implement efficiently. In contrast, multiple
isosurface extraction is easily applicable and provides images with sharp
boundaries in addition.
The goal of this project is the quantification of the rainfall at the ground
based on the 3D radar information (Z-R relationship).
Examples
Click on the images to see a magnified version.
The left image shows the target area in northwestern Germany near
Bonn. The right image shows the whole measurement area (circular with 100 km
diameter) as viewed from directly above. In the center is the city of Bonn,
the river Rhein runs from southeast (Koblenz) to northwest (Cologne).
The left image is a 70 degree angle view of the whole area. The
right image is a closeup of the rainfall event as seen from a 87 degree
angle facing northwest. The blue areas indicate high precipitation. The extent
of this major event is roughly 100 square kilometers. The height of all data
(relief and radar measurements) is exaggerated by a factor of 5.
Here the multiresolution approach for the terrain as well as for the rainfield
are illustrated. In the upper row you see the adaptive triangular and
tetrahedral grids for varying error thresholds (decreasing by a factor of 10 in
between from left to right). In the lower row are the corresponding images.
A time series (time interval 30 minutes) of a heavy rainfall event (moving from
left to right). Unfortunately, directly above the radar antenna no rainfall
information is available.
References
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T. Gerstner, D. Meetschen, S. Crewell, M. Griebel, C. Simmer, A Case Study on Multiresolution Visualization
of Local Rainfall from Weather Radar Measurements, in Proc. IEEE
Visualization '02, pp. 533-536, 2002.
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T. Gerstner, Multiresolution extraction and rendering of transparent isosurfaces, Computers & Graphics, 26(2):219-228, 2002. (shortened version in "Data Visualization '01", D.S. Ebert, J.M. Favre and R. Peikert (eds.), pp. 35-44, Spinger, 2001).
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T. Gerstner,
Multiresolution visualization and compression of global topographic
data, GeoInformatica 7(1):7-32, 2003.
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T. Gerstner, H.-P. Helfrich, and A. Kunoth
Wavelet analysis of
geoscientific data, in "Dynamics of Multiscale Earth Systems"
H.-J. Neugebauer (ed.), Lecture Notes in Earth Sciences, Springer, 2001,
to appear.
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The radar group at the Meteorological Institute of the University of Bonn
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