4.5.7 Plots of isosurfaces, 2d cross sections and particles with dvrp

The dvrp software developed by the RRZN (Stephan Olbrich, Carsten Chmielewski) allows a creation of plot sequences with PALM, which can be animated via a special plugin for internet browsers. With suitable graphic hardware even stereoscopic views are possible.
In contrast to the other kinds of visualization output realized in PALM (profil, iso2d and AVS), where the data is output in a format suitable for the plot software, the creation of plots via dvrp software is integrated in PALM, i.e. respective routines are directly called within the PALM code. The dvrp routines then output the graphic data (so-called plot-primitives, e.g. polygones of isosurfaces) in a special dvr format. Since the dvrp software is parallelized (i.e. each PE calculates the graphic data for its subdomain), the visualization of simulations with very large numbers of grid points is possible (which so far failed because of several problems: volume of the raw data, which rapidly may sum-up to several Terabytes; main memory size needed for graphic workstations, on which the visualization is to be carried out; the insufficient scalar (!) computing speed of commercial graphic software in case of such large numbers of grid points).

The coupling of dvrp software and PALM as well as the visualization of the model results via dvrp has been the main focus of the BMBF project "Application of tele-immersion in long-distance networks" (2001-2002), which was a joint project of RRZN, ZIB and IMUK. This work is currently continued by RRZN in the new DFG-funded project "EVITA - Untersuchung effizienter
Methoden zur visuellen und haptischen tele-immersiven Exploration
komplexer Volumen- und Strömungsdaten aus parallelisierten,
dynamischen 3D-Simulationen" (2005-2007).

The calls of the dvrp routines are contained within a PALM software package (see chapter 3.7). To use this package, the additional option -p “dvrp_graphics” has to be given in the mrun call. This automatically links the required libraries. Steering of the plot output is done via the package parameters (see chapter 4.2). In contrast to all other PALM output, dvrp graphic data are not output to local files but directly to a special remote computer which is defined via the package parameter dvrp_host. The default values of the dvrp parameters are cause the output to be directed to a so-called streaming server at the RRZN. Apart from graphic data an additional html file is created, which can be used by an internet browser to view the data (a special dvrp plugin is needed).

Since July 2001, the basic functionality of the dvrp software is installed in PALM and steerable via the package parameters. However, some code modifications may still need to be done by the user (e.g. in the subroutine plot_dvrp in order to define suitable color tables).
For further detailed information please ask Siegfried Raasch.

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