SNAZ Project Support - I

NOTE: click on an image to see a higher resolution one


First Step: 2D conversion to VTK

As a first step I converted these files to vtk format using Hank's VisIt vtk writer (visit_writer.c and visit_writer.h). I used an openDX reader for the Vulcan data as an example, see importvulcandata3D.c. However some of the variables need type "double" and Hank's writer only handles floats. I converted his writer to all doubles, visit_writer.c and visit_writer.h, and used snaz2vtk.c to convert the files. Some of the vector variables still give and "inf" or a "nan" in VisIt so I divided the values by the max-min value that I got from the PARAM.aic_M1pt92_90d_16_3 file (Some of the values in this file were missing the E of the exponent and I added them by hand).

These converted files and the conversion programs are in: /d/visusers/cristina/SNAZ/VTKDataNormalized and are readable by the graphics group. A set of time steps with the original doubles is here /d/visusers/cristina/SNAZ/VTKData. I also copied the same directories to the /project/projectdirs/mpccc/cristina/snaz of NERSC with read permissions for the group snaz.

Figure 1. Snapshot of the VisIt GUI showing a Pseudocolor plot of temperature.

Figure 2. First images of the 2D data.

Second Step: 3D conversion to VTK

The next step was to convert the data to 3D by replicating the 2D mesh around 360 degress and making the connectivity for hexahedral cells. I modified snaz2vtk.c to make the 3D cells using the original importvulcandata3d.c example.

Figure 3. 3D hexahedral mesh.

Figure 3. 3D hexahedral mesh reflected using VisIt Reflection operator, isosurfaces and vectors.

2D Entropy Evolution using VisIt

Figure 4. Entropy Evolution in 2D (logarithmic colormap)

MOVIE: Click here to see the time evolution

First images of the 3D Entropy using AVS/Express

Figure 5. 2D Entropy for T=740.50ms (logarithmic colormap).

Figure 6. Entropy (log scale) isosurfaces and velocity vectors for t=740.50ms.

Volume Rendering of the 3D Entropy using VisIt

One transfer function

Figure 7. 3D Volume Rendering of Entropy evolution.

MOVIE: Click here to see the time evolution

Another transfer function

Figure 8. 3D Volume Rendering of Entropy evolution.

MOVIE: Click here to see the time evolution

Comparison of isosurfaces using Express and Visit, I might like VisIt better actually.

Figure 9. 3D Isosurfaces of T=3025016.

Entropy isosurfaces and velocity vectors using Express

Figure 10. Entropy and velocity evolution.

MOVIE: Click here to see the time evolution

Entropy isosurfaces and velocity streamlines using Express

Figure 11. Entropy and velocity streamlines evolution.

MOVIE: Click here to see the time evolution

Express Reader

This is a very primitive Express reader for the snaz data based on the OpenDx reader that Don Fisher provided. To try it, download the express project tar ball, snaz_reader.tar.gz untar and unzip it (tar xzvf snaz_reader.tar.gz) , cd to the snaz_reader directory, and follow the instructions in the README. You will need a licensed Express installation. If you would like to see an illustrated README follow this link.

NOTE on making movies

For the movies made with VisIt I used the Python interface to make images of a good resolution and with lossless compression (1024x1024 PNG) and then I used ffmpeg to assemnble the movie. The version of ffmpeg that I used is the one that is included in the distribution of Ensight8. This page explains how to use it.

Cristina Siegerist, February 2007