Disable rotation on Z axis

Question

I am developing an application to register and display a 3D DICOM image using VTK, ITK, and QT.

I am running into some issues with the registration part.

I am using the ScaleVersor3DTransform, VersorTransformOptimizer, NormalizedCorrelationImageToImageMetric, and LinearInterpolateImageFunction for this.

The problem is that I need to lock or disable the rotation on Z axis. The only axis that can rotate are X and Y.

I tried getting the GetNumberOfParameters() from the transform and setting all its values to 1.0 (although I think the Z-rotation is the third position on the array), but that didn't seen to work.

What are my options?

Answer 1

You can minimize (or disable) a certain parameter by setting a very high scale for the parameter you do not want to optimize (using SetScales on the optimizer). In the case of a ScaleVersor3DTransform, no single parameter is representing the Z-rotation, so I am afraid it won't work out for your specific case.

You could consider to use a Euler3DTransform instead, for which the Z-rotation is a specific parameter of the transformation.