MeshTV: Scientific Visualization and Graphical Analysis Software

"More Than Just Pretty Pictures"

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Documents | Download Software | Features | Quantitative Data | Comparison of Data | Plot Types
Operations | User Interface | Animation of Data | Distributed Mode
File Formats | Sample Images

Description
MeshTV is an interactive graphical analysis tool for visualizing and analyzing data on two- and three-dimensional (2D, 3D) meshes. It is a general purpose tool that handles many different mesh types, provides different ways of viewing the data, and is virtually hardware/vendor independent while still providing graphics at the speed of the native graphics hardware.

Mission
LLNL developed MeshTV to help scientists analyze data produced by their physics and simulation codes. These codes continually implement state-of-the-art computer techniques so that new capabilities for viewing the data from these techniques is always needed. MeshTV developers work to stay abreast of the most current visualization needs of their scientific community.

Impact
With the large problems being run on simulation codes, scientific visualization and graphical analysis tools are necessary to understand the results from these codes and to obtain quantitative information for comparison against experimental data.

MeshTV differs from many other visualization tools since it handles multi-block data, mixed material zones, and multi-species materials. It handles many mesh types -- 2D and 3D multi-block rectilinear, curvilinear, and unstructured meshes. MeshTV takes advantage of the structure of the mesh to improve the speed of plotting the data.

Features

Quantitative Data -- An important aspect of MeshTV is that it provides quantitative data. These data are obtained through the following three techniques:

• Pick-and-query -- When the user picks a point on the plot with the mouse, MeshTV prints the coordinates and the value of the variable being plotted (such as pressure, temperature, or density) in a separate window.

• Value versus distance plots -- When the user "rubber bands" a line across the plot, MeshTV plots the value of the variable as a function of distance along the line in a separate window.

• Retention of axes during zoom, pan, and rotate operations.

Comparison of Data -- MeshTV provides comparison of data through the following features:

• Multiple graphics windows for side-by-side comparison.

• Overlaying of images.

• Simultaneous display of data from many different files (or different data from the same file) either in separate windows or overlaid.

Plot Types -- The plot types which MeshTV implements include:

• Material boundary plots (lines or filled areas for 2D mesh data, surfaces for 3D meshes).

• Iso-contours (lines or pseudo-color for 2D mesh data, surfaces for 3D meshes).

• Mesh plots.

• Vector plots.

• 3D surface plots of 2D mesh data.

• Stereoscopic viewing of any 3D image.

Operations -- Often scientists want to visualize the results of operations on their simulation data. MeshTV provides the following operations:

• Reflection about any axis.

• Orthogonal and arbitrary slicing of 3D data.

• Material species selection.

• Index selection (e.g., zoom in on a region which is specified by nodal indices).

• Algebraic and mathematical function manipulation of data -- MeshTV will plot the results of expressions involving arithmetic operators and mesh variable operands.

User Interface -- MeshTV has a Motif-based Graphical User Interface (GUI). It also has a command line interface that can be used either as part of the GUI or as a separate interface. MeshTV can read commands from a file as well. This enables users to write MeshTV scripts or to capture commands generated from the GUI during an interactive session. The ability to run MeshTV from a file allows the code to be run as a batch job or to repeat the same series of operations on successive files.

Animation of Data -- MeshTV can save a series of raster images, then replay them to produce an animation of the user's data on the screen. MeshTV can also save the geometry and display list information for a series of images. Replaying a "movie" from this geometry data allows the user to interactively rotate, zoom, or pan an object while the movie is being replayed..

Distributed Mode -- MeshTV can operate in a distributed mode. A simulation on a remote machine can send data directly to MeshTV while it is running. The user can interact with this data in the same manner as he/she interacts with data from a file. Many simulations on different machines can send data to a single MeshTV running on the user's workstation to be displayed in different windows.

File Formats -- There are two different file formats that MeshTV can read -- the graphics file produced by DYNA3D (which uses IEEE 32-bit floating point numbers) and the SILO format. SILO implements an application program interface expressly designed for accessing scientific data. The SILO library defines a set of objects for handling different meshes. Data in a SILO file is self-describing (name, array rank, dimension size, etc.). This enables MeshTV to display the names of the variables in the selected file as menu selections in the GUI so that the user knows the contents of the file and what can be plotted.

(a) Window 1 in (a) is a plot of density from a hydrodynamic simulation of two lanthanum nuclei colliding off-axis at 0.7 the speed of light. (Click to see larger image.)

Two distance plot lines have been rubber-banded on this image, and the plot of value vs distance for these two lines is shown in (b). Also, several points have been "picked" and are designated by letters. (Click to see larger image.)

A pop-up window (c) displays the output from the pick-and-query feature that allows scientists to extract quantitative information from a plot. In the strip below window 1 are icons of the contents of other windows.

Last modified: December 4, 2000.
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