[vtkusers] Confused about vtkLookupTable

[Mark Gooding]

Hello all,

The visualisation withing the software I'm trying write is much the
same as what is done in the vtkMedical examples. Previously I was
using the pipeline as in the first edition VTK book:

vtkStructuredData
vtkImageDataGeometryFilter
vtkPolyDataMapper
vtkActor

with the mapper using the vtkLookupTable.

Now my department has finally coughed up for the 3rd edition of the
book, I was changing my visualisation to follow the pipeline in that
book:

vtkStructuredData
vtkImageMapToColors
vtkImageActor

with vtkImageMapToColors using the vtkLookupTable

As far as I understand, this pipeline should be quicker because the
image is texture-mapped onto a single plane rather than each element
of a grid being coloured. Please correct me if I'm worng and it isn't
going to be faster!

So I have implemented this pipeline for one of the 3 orthogonal
planes, and left the other two planes with the old pipeline. ALL
PLANES ARE USING THE SAME LOOKUP TABLE.

The new pipeline (in 3D) shows a white with the odd dark spot. And in
a separate render window displayed normal to the plane, it shows as
just white. (screen shot at
http://www.robots.ox.ac.uk/~gooding/vtkbizarre.html ) Surely it should
show the image in the same range as the old pipeline?

Any suggestions as to what I'm doing wrong?

Cheers,

Mark