p.s., Re: Finding reference to the data actually being displayed

Note my suggestion was defining a custom DataRenderer.
To get a general context for this, see the tutorial at:

  http://www.ssec.wisc.edu/~billh/dr_tutorial.html

But you can probably get away with just the information
in my earlier email, and the visad/bom/BarbRendererJ3D.java
example. See its main() method for how to use a custom
DataRenderer.