Using many scalars in one filter

[Malcolm Drummond]

Hi All

I've just come back to VTK after a long absence, so I'm very rusty - please excuse me if I'm missing the obvious here. I'm trying to do something that's done regularly in AVS, but I can't figure out how to do it with VTK.

I would like to visualize borehole-logs with vtkTubeFilter but I need to map color and radius to different scalars (preferably  different scalar components of a vtkFieldData), not a scalar and a vector. For example, color could represent lithology and radius could represent magnetic-susceptibility. Is there any way to do this? Could it be done with a programmable filter or would I have to write my own filter class that uses field-data and maps components to radius, color etc.?

I once hacked a vtkGlyph3D to use field-data (scale, color etc. were set by array index) but if I have to do this sort of thing again I'd like to do it properly. Seems to me there are a lot of cases where the user may want to map many scalars in a filter rather than a scalar, a vector, a tensor. Would this capability be a welcome addition to the library ?

Any help appreciated! 

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