Custom Colormap Lookup Table for 'ColorOrientation' of DTI Volume?

ste · June 21, 2023, 6:32pm

Operating system: Ubuntu 20.04.6 LTS
Slicer version: 4.10.2

Would it be possible to import a custom colormap for the ‘ColorOrientation’ of a DTI volume?

Currently that option is locked to the conventional color-code:
R: Left-Right
G: Anterior-Posterior
B: Inferior-Superior
and interpolated colors for intermediate directions of fibers.

Different from the canonical convention, I would like to design/import a custom color-code to map such orientations. Is that possible?

If yes, how can I enable such option? Is there a specific file/configuration I can look into?

Thank You
S.

pieper · June 21, 2023, 6:47pm

It would be doable, but you would need to change the C++ code for that.

github.com

Slicer/Slicer/blob/d7c9a0dbd10552fac6eb33933ecc7c4fd0c8ed5f/Libs/vtkTeem/vtkDiffusionTensorMathematics.cxx#L686-L712


      
          case vtkDiffusionTensorMathematics::VTK_TENS_COLOR_ORIENTATION:
            // If the user has set the rotation matrix
            // then transform the eigensystem first
            // This is used to rotate the vector into RAS space
            // for consistent anatomical coloring.
            v_maj[0]=v[0][0];
            v_maj[1]=v[1][0];
            v_maj[2]=v[2][0];
            if (useTransform)
              {
              trans->TransformPoint(v_maj,v_maj);
              }
            // Color R, G, B depending on max eigenvector
            // scale maps 0..1 values into the range a char takes on
            cl = vtkDiffusionTensorMathematics::LinearMeasure(w);
            rgb_temp = (rgb_scale*fabs(v_maj[0])*cl);
            *outPtr = (T)tensor_math_clamp(rgb_temp, (double)VTK_UNSIGNED_CHAR_MIN, (double)VTK_UNSIGNED_CHAR_MAX);
            outPtr++;
            rgb_temp = (rgb_scale*fabs(v_maj[1])*cl);
            *outPtr = (T)tensor_math_clamp(rgb_temp, (double)VTK_UNSIGNED_CHAR_MIN, (double)VTK_UNSIGNED_CHAR_MAX);

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Custom Colormap Lookup Table for 'ColorOrientation' of DTI Volume?

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