[Insight-developers] compose affine with header filter?

[Luis Ibanez]

Cory,

You are right,

The implicit transform that is stored in the itkImage
metadata can only describe a combination of:

1) Translation (via the origin)
2) Rotation / Reflection (via the Direction matrix)
3) Anisotropic scaling (via the spacing)


Combining these three modifications, it is not possible
to represent a generic Affine Transform.

In particular, as you pointed out, we can't represent
shearing (at least not for a generic case).


--


Michael:


The filter that you are describing will have to be
limited to composing the existing image grid with
only the following operations:


1) Translations
2) Rigid rotations & Reflections (flipping)
3) Anisotropic scaling parallel to the grid.


I'll be happy to have a phone /skype conversation
if you want to go about the details.

---

Also,

if you are writing your first ITK, you may find
useful to look at this presentation:
http://www.na-mic.org/Wiki/images/b/bc/Insight-Writing-a-New-Filter.ppt