[vtkusers] Fwd: vtkOpenGLProjectedTetrahedraMapper vs vtkUnstructuredGridVolumeRayCastMapper

[Luke Dodd]

At the moment I am a similar issue.

I've found that OpenGLHAVSVolumeMapper seems to have problems with the
opacity. My results are not as off as yours, but dropping in
OpenGLHAVSVolumeMapper shows something too transparent to see
properly.

In my vtkVolumeProperties I set ScalarOpacityUnitDistance to a smaller
value - for VolumeRay and ProjectedTetra this increases opacity enough
to see results, but for HAVS it does not seem to have any effect at
all.

Are you calling setScalarOpacityUnitDistance? Perhaps this could be
part of the problem. Perhaps someone else knows more about the opacity
settings on the different mappers.

In my code VolumeRay and ProjectedTetra show pretty much the same
thing - they seem to be working as expected for me. Is the only thing
being changed the volume mapper?

Best Regards,
Luke


On 9 June 2010 15:21, Artem Babayan <artem.paraview at googlemail.com> wrote:
> Hello,
>
> I have the following situation:
>
> 1) 3D scalar field defined on non-uniform Cartesian grid is read from
> .vtk  file with vtkStructuredPointsReader
> 2) Read data then fed to to vtkDataSetTriangleFilter
> 3) Color and opacity map are set.
> 4) 3D filed is visualised using vtkUnstructuredGridVolumeRayCastMapper
> or vtkOpenGLProjectedTetrahedraMapper or OpenGLHAVSVolumeMapper
>
> As a result -- I've got 3 completely different pictures (attached 1st
> for  vtkUnstructuredGridVolumeRayCastMapper, 2nd for
> vtkOpenGLProjectedTetrahedraMapper and 3rd for vtkOpenGLHAVSVolumeMapper)
> -- ignore the blocks as they are irrelevant here. Why is it so and
> which one is correct? It looks like at least vtkOpenGLHAVSVolumeMapper
> cannot 'see'
> values below certain level.
>
> If it is of any help -- the data range is from 1e-25 to 14.0 and the
> non-uniform Cartesian grid is non-uniform in z-direction only.
> The grid size are the following: dx==dy==25 , dz[] = {0, 4, 12, 30,
> 70, 150, 290, 670, 1020}
>
> Best wishes
> Artem
>
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