Display of two objects

Hi everyone,

I have a single file containing information about a river salinity and bathymetry(the ground).

I would like to:
- read this file and create two different objects (ground and salinity volume);
- construct a scene graph with both;
- display them together at a spreadsheet cell.

I would also like to be able to manipulate them separately, for example, performing clipping at the volume representing the salinity, triangulating the bathymetry, or just showing one of them at a time, etc.

I don't have much experience using VisAD, so don't know how to accomplish these tasks exactly.
Should I custom a DataRenderer, DisplayRenderer and a ShadowType?

Thanks in advance,