Volume Rendering Demo

This page demonstrates volume rendering in Java. The base code is an application written by Doug Gehringer at Sun, to whom I am grateful. I made an applet of the application and Doug has subsequently cleaned up some of the worst things I did. The source code is available from the J3d site. My (Dorman's) work was supported by the National Science Foundation under Grant No. 9403587. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. To get the source code (including the applet) click on Source .

What is necessary to run this applet?

You must install Java3D, available for IBM AIX, Solaris Sparc, Windows, HP-UX, Linux, IRIX and Mac OS X. For more detailed instructions, see the Java3D FAQ from Sun or the FAQ at J3D.org. Java3D uses Java (version 1.3.1 or later) as its base.  The Netscape and Mozilla browsers either include Java or have links to java download sites. Netscape 7.1 is bundled with Java, but not the most recent version.  The Java Virtual Machine in some versions of Internet Explorer from Microsoft  is based on an version of Java too old to support Java3D and, because of a contract dispute, Microsoft is not upgrading it.  See the discussion.  (However, the Internet Explorer versions from IBM do not use the old Microsoft Java.) The downloads from Sun are available in two forms, runtime (RT) which allows execution of Java object code, and software development kit (SDK) which allows compiling Java source into object code.

Configurations which I know to work are Netscape, Mozilla and Internet Explorer under Win98 SE, Netscape, Mozilla and Internet Explorer under Win XP, and Mozilla and Netscape under RedHat Linux under Solaris 8.

What can you do with the applet? The viewer will display the image using preset parameters. Dragging the mouse across the screen with the left button depressed will rotate the image. The upper slider controls how much of the (blue) anomalously high velocities are visible and the lower slider controls how much of the (red) anomalously low velocities are visible. Play with it!

There are three datasets available here:

The first image is of compressional velocities under the Tonga island arc and Lau Basin. (Zhao, Xu, Wiens, Dorman, Hildebrand, Webb, Science , V278, pp254-257, 1997) The size of the grid is about 1000 km horizontally and about 675 km in depth. The blue object is the Pacific plate, which is being subducted beneath the island arc. The reddish material is low-velocity (presumably hot and magma-rich) material which forms the source material for the back-arc spreading center and the arc volcanism. The "new science" was that the volcanoes and the spreading center are fed from sources which are more-or-less connected, and that the spreading centers (indicated on the figure by red lines) are somewhat to the east of the main body of the source material.  The sinking of the plate pulls material from the Lau Basin eastward and this seems to cause the spreading center to migrate to the west to stay above the magma source. To see this image, click LABATTS .

The second dataset is of the seismic velocity structure beneath Southern California, using travel times from local earthquakes and controlled sources. The model extends from the US-Mexico border to the southernmost Coast Ranges and is aligned parallel to the coast. The dimensions are 400km x 640km x 33km (inlandxlongshorexdepth). The image shows variations between the local velocity and the mean velocity for that depth for the entire model. The overlay shows the boundaries of the state of California as well as major faults. The Salton Sea is not shown. The latitude/longitude grid interval is 2 degrees. From Hauksson, E., J. Geophys. Res., 105, 13,875-13,903, 2000.
To see the compressional (P) image click SOCALVP. For the shear velocity image, click SOCALVS . For the Vp/Vs ratio, click SOCALVPVS .

The third image is of the spectral density of ocean waves (swell) measured by an array of Ocean-Bottom Seismometers at a depth of 30 meters offshore of Southern California, more specifically off Marine Corps Base Camp Pendleton. At the center of the plane defined by the red and blue vectors, the horizontal slowness is zero (infinite velocity) and the maximum values are 200 seconds per kilometer. Up (opposite the blue axis) is increasing period, with the greatest value being 16 seconds. The strongest component is in the ENE direction with a subsidiary peak in a more northerly direction. These coordinates are what I remember and the calculations were made several years ago so the details are subject to correction. For more information, see ABM Experiment Report To see this display, click SWELL .

Forthcoming features:

(1) Put a map on the top of the model volume. (done by Doug)
(2) Put scales the model.
(3) Show earthquake hypocenters.

All the overlay plots were created using GMT (Generic Mapping Tools, Wessel, P. and Smith, W. H. F., EOS, Transactions AGU, 76, 329, 1995).

If anyone has any suggestions or comments, or difficulty, let me know.

LeRoy Dorman
ldorman@ucsd.edu

Last Modified 20040311 lmd

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