USC Component of DoD, DoE and NASA Activities:
Graphical User Interfaces and Enabling Technologies.




G3D - A Graphical User Interface for PDE Simulations

Visualization tools devised by the University of South Carolina are used for assessment of simulations as well as for improving PICS groundwater code and algorithm development. Primary effort has focused on G3D (an integrated graphical user interface used for post-processing simulations, for preprocessing models and 3D grid generation) and modules which use the Tracking/Steering library to couple to the simulators executing on remote parallel supercomputers:

A number of auxillary tools have been produced to facilitate model development by practicing hydrologists, as well as assisting in the development of the GCT series of codes. I/O capabilities are also being incorporated for user readable data as well as binary distributed files for the Paragon. Prototype utilities also have provided access to GIS (Geographic Information System) data bases to import grids from topographical surface measurements. This prototype may be modified to assimilate stream levels and historical contamination records as well as subsurface data for soil properties and contaminant distribution.



Interactive Tracking and Steering Library.


In order to efficiently calibrate models, characterize contaminants and media properties, and optimize remediation schemes, an interactive capability is required. Typically, the modeler needs to observe the effects of current parameter settings, and based on those observations, they must then be permitted to alter the parameters in a non-intrusively manner during the simulation. This methodology may also be used to test and fine tune numerical algorithms for accuracy, robustness, and efficiency without affecting load balancing.

[Image of Interactive Controller for Parallel Machines]

The South Carolina component has developed a tracking and steering library to connect parallel machines and workstations to enable this functionality. In this library the remote MPP machine is set as host with a graphics node that handles requests from client workstations in such a manner so as not to disturb the load-balance of the compute nodes (unless the applications programmer so wishes). This node also uses the compression modules (see below) and the XDR libraries with remote procedure calls to transfer the data to the client workstation for processing and interactive analysis.

On-line Steering Library Manual.


3D Data Compression

Current bandwidths preclude the interactive simulation of large scale models on remote supercomputers if even moderately sized data sets are to be transfered for analysis or steering. The wavelet analysis research group at the University of South Carolina have developed higher dimensional multiresolution-based data compression and processing libraries to enable efficient and effective assessment of interactive simulations on massively parallel platforms.

The following image (on the left) provides a comparison of the reconstructed images from compressed files with high levels of compression for the original simulated pressure field. The image on the right utilizes the enhanced compression encoders applied to a contaminant transport data set with stronger gradients.

3-D EZM Data Compression:
Original and Compressed Data


3D Data Compression Comparison
with rates from 172-1200

Comparison of compressed data to original scalar
field: (a) Original data, and compression rates of
(b) 172, (c) 493, and (d) 1200 times compression.

The figure on the right consists of images all rendered using identical orthogonal slices and an isosurface of .3 of maximum concentration percentage.


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