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 original (application) code is available from the  J3d  site.

What is necessary to run this applet:
(1) You must have the capability to run Java1.2 (AKA Java2).  The minimal thing to get is the Java Runtime Environment.  This allows you to execute Java2 bytecode. If you want to do development work, get the Software Development Kit (SDK).  Both are available from the  Java 2  site.  The SDK includes the Java 2 browser plugin, which allows your browser to use Java 2.  The Java2 software is available for the following platforms:  Solaris for Sparc and Intel hardware (Solaris 8 requires fewer patches), Windows 95/98/NT, Linux and SGI IRIX.  To verify that your Java2 installation works, try the Sun's  Java2 DEMOS.
(2) You must install Java3D, available for Solaris (Sparc only),  Windows, Linux and IRIX.  Get it from  Java3D . For more detailed instructions, see  the Java3D  FAQ.  To verify that your Jav3D installation was successful, try the Dan Selman's  BenchJ3d.  (This was written by a professional programmer, not an amateur like me).
(3) For Wiin/NT and Linux, Netscape 6  Preview Release 3, which is bundled with  Java2Beta works well.  Just install
the Java3D into C:/Program Files/JRE/1.3.0_01 and away you go.  At least under Win98.  I have not tested this under Linux  Using NS6 a plugin is not necessary.

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!

This works under Netscape 4.x and 6 on my WIN98 notebook and on my Sun (Solaris 8) workstation using  Netscape4.7 as well as appletviewer.

There are four 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 800 km horizontally and about 400 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 center (not indicated on the figure) is somewhat to the east of the main body of the source material.  This seems consistent with the observation that the spreading center is migrating to the west.
To see this image, click LABATTS.

The second image is of shear velocity anomaly under the East Pacific Rise as determined by the MELT experiment (Forsyth and others, Science, V280, pp1215ff, 1998).  The size of the grid is about 3 degrees (200 km) horizontally and 150 km in depth.  The top of the model has two blue wedges, (plate segments, which thicken as they move away from the spreading center, which is in the center of the model.  The reddish body centered between the two plate segments (but deeper) represents low-velocity material which is magma-rich.  There is an appendix reaching out to the west which may form part of the feeder system to the seamounts which are more common to the west of the EPR than to the east. To run the applet click MELT.

The third 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. 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 fourth image is a 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.
(2) Put scales the model.
(3) Show earthquake hypocenters.
 

If anyone has any suggestions or comments, I'd appreciate hearing them.

LeRoy Dorman
ldorman@ucsd.edu