[vtkusers] Scaling with VtkTransform and VtkLookupTable

Schober Beatrix [STEMMER IMAGING GmbH] b.schober at stemmer-imaging.de
Fri Feb 17 02:50:03 EST 2017

Good morning!

I am a bit confused about following behaviour. I tried to find an answer / solution, but spent already more than a day with that. Maybe the behaviour is correct, I just misunderstand it?

I have a point cloud (VtkPolyData), using a VtkTransform Filter to scale the z-values. As I want the points to be displayed colored, I use the vtkLookupTable as well as the ScalarBarWidget to display the lookup table.
Before scaling my z-range is 98 - 255, after scaling (2*) the range is 196 - 510.

If I do not change the VtkLookupTable's table range (it is still 98 - 255), the colors are mapped correctly from 196 to 510. If I change the table range to 196 - 510 and the mapper's scalar range to 196 - 510, in order to get a correct valued ScalarBarWidget (range 196 - 510), only colors from 196 to 255 are mapped, everything else not. (The picker shows the correctly scaled point data.)

My questions: Why is the mapping wrong if I update the scalar range / lookup table range? How can I achieve a correctly scaled ScalarBarWidget (196 - 510)?

Thank you very much in advance for your support!

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