[vtkusers] mapper question..

[K.R.Subramanian]

Glen.Coates at csiro.au wrote:

> On Sat, 1 Feb 2003, K.R.Subramanian wrote:
>
> >
> > I am trying to display images using
> >
> > vtkPlaneSource (1x1 size)
> > vtkTexture
> >
> > and sending this to an actor
> >
> > The texture data is in floats, so the docs say it has to be mapped through
> > a lookup table - however, I have tried to specify a lookup table(a gray scale lut - with
> > just the value component from 0-1) but this doesnt seem to work - I get a
> > plain rectangle. Without a lookup  table specification, it uses the red to blue color scale by
> > default.
> >
> > If I used unsigned chars and dont do any of the lookup table, it works correctly.
>
> I'm not entirely sure if this is the same problem, but when I had problems
> using float texmaps, I found it was because VTK expected the floats to be
> in the range [0..1], so dividing by the pixel maxval (ie 255 for 8bpp,
> 65535 for 16bpp etc) makes everything work nicely.

Is this true? I havent tried this, but definitely dont see anything about this in the docs.
Or is the scalar range assumed to be within 0-1 and thus need to be reset?

    -- krs

>
>
> --
> Cheers,
> Glen
>
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--
K.R.Subramanian                        Phone: (704) 687-4872
Department of Computer Science         FAX:   (704) 687-4893
UNC Charlotte, CARC 311                Email: krs at cs.uncc.edu
Charlotte, NC 28223-0001               Web: http://www.cs.uncc.edu/~krs