[Insight-users] Initialize optimizer for registration

[laurent.paul at club-internet.fr]

Hi all!

I try to register two volumes.
I use VersorRigid3DTransform, CenteredVersorTransformInitializer, VersorRigid3DTransformOptimizer, MeanSquaresImageToImageMetric, LinearInterpolateImageFunction and ImageRegistrationMethod.
My problems are following:

1)I'd want to get the size and spacing of volume to initialize the optimizer as 
optimizerScales[3] = 1.0 /(10.0 * spacing[0] * size[0] );
optimizerScales[4] = 1.0 /(10.0 * spacing[1] * size[1] );
optimizerScales[5] = 1.0 /(10.0 * spacing[2] * size[2] );

That's the way you adviced in a previous message on mailing list.
I manage to get the sapcing with the GetSpacing() method, but there's no the equivalent GetSize() method (except in the class ImageRegion).
Have I use the ImageRegion class to get the size of my volume?

2)Which image spacing and size have I to get? I think it should be the fixed image but I'm not sure. Can you light me?

Thank you!

Laurent.