[vtkusers] Plotting vectors from a surface

[Kenneth Porter]

I have some data collected nominally over an X/Y plane, with minor 
variations in Z due to the data collection hardware. Each point has two 3D 
coordinates (6 numbers): an ideal and an actual location. I'm looking for 
suggestions on how best to present this. I'm thinking I want a "forest" of 
vectors showing the error (difference between each point pair) color-coded 
to indicate the degree of the error.