Rhonda J. Vickery

Interactive visualization of ocean circulation models

Visualization of computational oceanography is traditionally a post-processing step. This batch orientation is clumsy if one wants to observe the effect of a wide range of parameters on the solution. This paper describes the conversion of an ocean circulation model from this traditional design to an interactive program in which the computed solution is viewed in real-time over a wide-area network and the user is given the ability to change the model parameters and immediately observe the impact this has on the solution.

Web-Based High Performance Remote Visualization

This work describes a web browser-based remote visualization capability for large datasets. We discuss recent enhancements including access to databases and remote resources, as well as the addition of two image compression algorithms and their effect on performance. Results indicate that the existing sequential unified- channel image run transmission (SQUIRT) image compression algorithm performs best for large bandwidth situations while the new binary set splitting with k-d trees (BISK) algorithm works better than the previous JPEG compression scheme. The results from a study on encryption effects on the data stream show that encryption does not add a significant amount of overhead.

Computational Science and Engineering Advances Understanding of Complex Unsteady Flows in High Performance Fans and Compressors

The ability of high fidelity simulations to more accurately model complex flow phenomena in high performance military fans and compressors is demonstrated. Challenge Project CII continues to investigate how blade row interactions and distortion transfer impact fan and compressor performance. Simulations accomplished through this Challenge Project have produced improved geometric, physical, and numerical fidelity results than previously possible, allowing the design of next generation engines to achieve unprecedented performance

SSH-Enabled ParaView

ParaView is a very powerful visualization tool used by many in the Department of Defense (DoD) high performance computing (HPC) community. It is both fast and flexible. It performs well on a user’s desktop, but it can also scale to take advantage of clusters and large shared memory machines. Recently, ParaView has been adapted to run on the Linux clusters at the US Army Research Laboratory DoD Supercomputing Resource Center (ARL DSRC) using the Load Sharing Facility (LSF) batch queues. This method makes heavy use of Secure Shell (SSH) port forwarding to move data between the cluster nodes and the user’s desktop. The method is fast, convenient, and secure. Unfortunately, not everyone can use SSH port forwarding. For example, some users may not have access to servers that allow port-forwarded traffic. Also, there are users that are specifically banned from initiating a port forward from their desktop. To solve this problem, we have developed a version of ParaView that does not use TCP/IP sockets between the client and the server. Instead, the data is passed through the SSH standard in/out. If the user wishes to use a batch queue, a helper script handles the communication between the login node and the nodes that are allocated to the user. This paper describes the implementation of an SSHenabled ParaView. It then empirically compares our version to various other methods of running ParaView in the DoD HPC environment. Finally, it helps guide HPC users to determine the method that best fits their needs. This work benefits the DoD HPC community by making ParaView client/server available to users that have been previously unable to use it.

Web-based secure high performance remote visualization

This paper describes recent work on securing a Web-browser-based remote visualization capability for large datasets. The results from a security performance study are presented.

ISTV: Interactive Structured Time-varying Visualizer

The Interactive Structured Time-varying Visualizer (ISTV) visualization system, written at the NSF Engineering Research Center for Computation Field Simulation, Mississippi State University, was originally designed for high-performance interactive visualization of very large oceanographic models. However, its design is general enough for other scientific visualization work, and it has been used with structured datasets from a variety of domains including computational fluid dynamics, electromagnetic simulations and medical imaging. ISTV is written in C using OpenGL for graphics and X/Motif for the user interface. Initially written for SGI IRIX workstations, ISTV has also been ported to Sun Ultra workstations with OpenGL hardware support. During the past two years, computational grid resolutions in global models the authors routinely work with have increased by a factor of 16; their visualization products have adapted to this explosive growth by adopting more efficient data access techniques while retaining the ability to work with model output in its native format. ISTVs data model and distributed visualization capabilities are discussed below; the distributed visualization capabilities include a data server using the message-passing interface (MPI) to communicate with the visualization front-end, providing improved access to data using both multiprocessor machines and networks of heterogeneous machines. The simultaneous visualization of several datasets with varying temporal and spatial resolutions in a single view volume is also supported by ISTV; case studies are presented demonstrating this capability. Effective analysis of ocean flow requires the identification of vortical structures; ISTV provides a visualization technique using a two-dimensional mapping with a hue-saturation-value color wheel, giving researchers insight into ocean eddy structures while avoiding the display clutter associated with conventional vector field visualization techniques.

Visualizing confusion matrices for multidimensional signal detection correlational methods

Advances in modeling and simulation for General Recognition Theory have produced more data than can be easily visualized using traditional techniques. In this area of psychological modeling, domain experts are struggling to find effective ways to compare large-scale simulation results. This paper describes methods that adapt the web-based D3 visualization framework combined with pre-processing tools to enable domain specialists to more easily interpret their data. The D3 framework utilizes Javascript and scalable vector graphics (SVG) to generate visualizations that can run readily within the web browser for domain specialists. Parallel coordinate plots and heat maps were developed for identification-confusion matrix data, and the results were shown to a GRT expert for an informal evaluation of their utility. There is a clear benefit to model interpretation from these visualizations when researchers need to interpret larger amounts of simulated data.

RADAR Analysis for Proposed Predator Design

Recently the Predator System Program Office (SPO) wanted to evaluate proposed design changes. The complete evaluation included prediction of performance against a range of enemy threats in multiple roles. A portion of that analysis included synthetic radar cross section (RCS) generation and evaluation. For RCS prediction the team used Xpatch® which is a set of prediction codes and analysis tools that use the shootingand- bouncing ray (SBR) method to predict realistic farfield and near-field radar signatures for threedimensional (3-D) target models. The requirement was for over 15,000 Xpatch runs, with approximately half of those jobs requiring one hour of computer time for an individual run. This substantial computer time requirement was met using DoD High Performance Computing Modernization Program (HPCMP) resources. This presentation describes how the Xpatch RCS results were produced and provided to the SPO. The presentation includes details of how high-performance

Volume visualization of 5D sedimentation models

We implemented a hybrid immersive visualization system for a five dimensional (5D) coupled bottom boundary layer-sedimentation model. This model predicts sediment resuspension, transport, and resulting distributions for shallow water regions on continental shelves. One variable of interest, suspended sediment concentration (SSC), is 5D and varies by longitude, latitude, depth, time, and grain size. At each grid point there are twenty values for SSC, representing grain sizes ranging from 2.36 to 3306 micrometers . Currently the most common methods of analyzing the SSC distribution are only 2D, e.g., point profiles, cross-sections, map views at equal water depths, and time series. Traditional methods require multiple sets of plots that are analyzed manually. Good 3D methods are needed that will allow researchers to investigate the complex relationships between variables and see the underlying physical processes more comprehensively, especially within the wave boundary layer close to the ocean bottom. This paper presents the work in progress on the motivation, requirements, and overall design of the visualization system, along with the latest efforts to incorporate volume visualization as an effective means of understanding the SSC variable. The system is optimized for deployment in a CAVE. We also describe the extension of this system to other problem domains.

Effects of Disorientation on Human Spatial Cognition: Object Localization in Virtual Environments

The present research examines the effects of disorientation on human ability to locate objects in space in a virtual environment (VE). Participants were asked to memorize the location of virtual objects. After memorizing object locations, they were asked to indicate where the objects were located while inside a virtual chamber. This procedure was repeated in eyes-closed and disoriented conditions. Subject pointing responses were used to measure memory for the relative location of objects in virtual space. This method was extended from Wang and Spelkes (2000) research in a real-world setting. The results show systematic individual differences in the effects of disorientation on the ability to locate objects in space. Two groups of subjects, initially disoriented in the eyes-closed condition, use a memory strategy to locate objects, while another group, less easily disoriented in eyes-closed, shows degraded performance in the disorientated condition. The results are discussed with respect to configural and egocentric theories of spatial cognition.