[Insight-developers] another image transform question

[Damion Shelton]

Ok, the previous issue is resolved. A more complicated case arises in 
itkMeanSquaresImageToImageMetric, which assumes that the transform is 
available in the image class. Rather than just transforming indices, 
this class loads the image transform in order to transform points, a 
capability which is not currently provided in the image itself.

I see two solutions:

1) This class could be modified to create a local (presumably affine) 
transform by obtaining the origin and spacing information from the 
image in question.

2) Image could maintain a local affine transform, which is implicitly 
created from origin and spacing and cannot be modified. This would be 
similar to the "default" case from before. The Image implementations of 
TransformBlahToBlah need not actually use this transform (for 
efficiency's sake) but it looks like it would be convenient to have 
around for other classes.

I think the second option is the way to go. Opinions?

-Damion-