[vtkusers] lookup tables for vtkSmartVolumeMapper

[Mark Roden]

Hi all,

I'm trying to move into using the vtkSmartVolumeMapper for rendering
CT series, and I'm running into some problems.

When I was using the texture mapper 3D mapper, I had these lookup tables:

These tables were applied after shifting the data by +2000 so that the
data could be in the unsigned short (instead of signed short) space.
                volumeColor.AddRGBPoint(1000, 0.0, 0.0, 0.0);
                volumeColor.AddRGBPoint(1400, 1.0, 0.5, 0.3);
                volumeColor.AddRGBPoint(1800, 1.0, 0.5, 0.3);
                volumeColor.AddRGBPoint(2200, 1.0, 0.5, 0.3);
                volumeColor.AddRGBPoint(2450, 1.0, 1.0, 0.9);
                volumeScalarOpacity.AddPoint(1000, 0.00);
                volumeScalarOpacity.AddPoint(1400, 0.05);
                volumeScalarOpacity.AddPoint(2200, 0.15);
                volumeScalarOpacity.AddPoint(2450, 0.75);//don't want
it to be too opaque,
                volumeScalarOpacity.AddPoint(5150, 0.75);//don't want
it to be too opaque,

for muscle and bone, and


                volumeColor.AddRGBPoint(1000, 0.0, 0.0, 0.0);
                volumeColor.AddRGBPoint(1400, 1.0, 0.5, 0.3);
                volumeColor.AddRGBPoint(1800, 1.0, 0.5, 0.3);
                volumeColor.AddRGBPoint(2150, 1.0, 1.0, 0.9);
                volumeScalarOpacity.AddPoint(1000, 0.00);
                volumeScalarOpacity.AddPoint(1800, 0.00);
                volumeScalarOpacity.AddPoint(2400, 0.05);//don't want
it to be too opaque,
                volumeScalarOpacity.AddPoint(2450, 0.5);//don't want
it to be too opaque,
                volumeScalarOpacity.AddPoint(5150, 0.75);//don't want
it to be too opaque,

for bone.  Both of those also had

                volumeGradientOpacity.AddPoint(0,   0.0);
                volumeGradientOpacity.AddPoint(30,  0.05);
                volumeGradientOpacity.AddPoint(60,  0.05);
                volumeGradientOpacity.AddPoint(65535, 0.25);

For the gradient opacity.

Why don't the results of these lookup tables look identical?  What is
going on that requires that I redo all the lookup tables?  Shouldn't
the results look identical, regardless of the rendering method used,
especially if the inputs and LUTs are the same?

Thanks,
Mark