[Insight-users] ITK 3.6 : Serial Transformations

[Rupert Brooks]

Hi,

One thing that caught my attention about the upcoming ITK release was
the plan to move the Serial Transformation class to the Review
directory (its in the low priority items).  I think the idea of
combining transforms would be a great addition; I have used this sort
of thing on occasion, and I am very curious if anyone else uses
combinations of transforms and what their requirements and thoughts on
the topic were.

The thing is, the paper chosen does not support the registration
framework, where as another paper on the same topic does.  That paper,
however, has its own set of limitations. I think that a class for
serial or combined transforms is a valuable addition. However, I worry
that if done prematurely, we might get stuck with a limited interface
due to ITKs backwards compatibility policies. I think some serious
thought should be put into how this interface should work before
committing to a particular implementation.

Links:
Serial Transforms (proposed for ITK3.6):
http://hdl.handle.net/1926/487
Combined Transforms
http://hdl.handle.net/1926/197

At the very least i think that any such class should support:

   1. The registration framework - ie - proper Jacobians - (one has to
transform one Jacobian by the spatial Jacobian of the other transforms
in certain cases).
   2. An arbitrarily long chain of transformations
   3. The ability to have some fixed and some parameterized transforms
- by this i mean that some transformation parameters do not appear in
the GetParameters and Jacobian methods.  (Sometimes part A is always
at 45 degrees to part B, for example.
   4. Some sort of intelligent interaction with the transform reader
and writer classes.

I suppose that I should kick myself a bit, for not having reviewed
either of these papers at the time.  Anyway, im not saying that all
possibilities should be working immediately, but just that the
interface should be clean, so we don't have problems later.

Thoughts?

Rupert B


-- 
--------------------------------------------------------------
Rupert Brooks
McGill Centre for Intelligent Machines (www.cim.mcgill.ca)
Ph.D Student, Electrical and Computer Engineering
http://www.cyberus.ca/~rbrooks