[vtkusers] Scaling with VtkTransform and VtkLookupTable

[David Gobbi]

Hi Bea,

There is something missing from your explanation: how are you setting the
scalars for your points?  The lookup table maps scalars to colors, and
scalars are not changed by vtkTransformFilter.

 - David


On Fri, Feb 17, 2017 at 12:50 AM, Schober Beatrix [STEMMER IMAGING GmbH] <
b.schober at stemmer-imaging.de> wrote:

> 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!
>
>
>
> Bea
>
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