> What I'm trying to do is to render a "volume" of a cylinder rather than the
> surface. So I guess I should use manifold dimension=3?
For a volume, yes you need manifold dimension=3.
> The raw data is a 2-D matrix in r-z coordinate. Since the data is symmetric
> in "theta" direction, I want to render the 2D sample data into 3D volume
> data by simple copying them for different "theta" in r-theta-z coordinate
> (see the attached 2d.jpg and 3dvolume.jpg). However I am not quite sure how
> to use the CylindricalCoordinateSystem in Gridded3DSet. Is there any example
> I can read for this case?
See Test11.java and HSVDisplay.java in visad/examples.
To do a true volume rendering, you'll need to resample
to a Linear3DSet, in (x, y, z) rather than in (r, theta, z).
Note that (x, y, z) will be the reference RealTupleType
for your CoordinateSystem. Use ScalarMaps x -> XAxis,
y -> YAxis and z -> ZAxis.