How to understand feature "Shift" in module "Volume Rendering"?


There are two questions that I was not able to figure out. Please help me. :wink:

  1. I was trying to get the 3D coords of the skin-surface of the back surface from a vertebral MR, to get the posterior-anterior axis given the inferior-superior axis and left-right axis.

Is there a module to help do that?

  1. When showing the volume rendering, the feature “Shift” (as shown in the screenshot below) changed the valid volume. How should I understand the disappeared volume when Shift is enlarged? And how the extra pure-black volume was added when Shift is reduced?

It is equivalent with adding/subtracting a constant to voxel values.

What it actually does it shifts volume rendering transfer functions, which you can find in the “Advanced” section.

Hi Iassoan,

Thank you for your reply!
It seems that the “Advanced” section is kind of advanced for me. :sweat_smile:

Could you please post some link or tutorial, or even source code about how the feature “Shift” is applied on voxel processing mathematically?

Thank you in advance!

Shift is equivalent to adding/subtracting a constant value from the voxel values. You can read more about volume rendering in the VTK Textbook.