Tips and Tricks for ITK Registration¶

See Integration of ITK Algorithms in MeVisLab for general information about the ITK-MeVisLab bindings.

If the optimizer offers a field named Scales, you should make use of the possibility to scale your parameters, indeed it is necessary to fill in this field. The itk Book tells us for the itkRigid2dTransform:

“Keeping in mind that the scale of units in rotation and translation is quite different, we take advantage of the scaling functionality provided by the optimizers. We know that the first element of the parameters array corresponds to the angle that is measured in radians, while the other parameters correspond to translations that are measured in millimeters. For this reason we use small factors in the scales associated with translations and the coordinates of the rotation center”.
It may occur that the registration result contains one or more slices that are just black. This can be due to the interpolation and you may get a better result, if you use a different interpolator.
If you have already an idea of how the moving image must be transformed (e.g. you know that it must be translated in x-direction for about 10 mm) you should chose the initial position of the optimizer in conformity. This will perhaps accelerate and improve the computation.