Across the Nth dimension...and onto the next

hello again,

today's question is about projections.  in the app i'm working on, data
are represented in different dimensions -- 2D for a surface map of model
results, 3D for a snapshot of what's going on underground, 4D for the
time series of snapshots.

by using getSamples() to extract the data points, i can map one onto
another; iterating through the various float[][]s.  it occurs to me,
however, that this violates the efficiency rule of VisAD (cf. the
Developer's Guide, section 3.9).

the question: is there a higher-level means for projecting, say, a 2D
map onto a surface of a 3D dataset?  the developer's guide shows an
example of subtracting FlatFields, but they had the same number of

thanks yet again,