users > RE: Inverse consistent bridging registrations
Feb 9, 2013  02:02 PM | Greg Jefferis
RE: Inverse consistent bridging registrations
Originally posted by Torsten Rohlfing:
Hi Greg:

I think you mean the "--ic-weight" option in warp and warpx, not reformat?
yes - typo.
Anyway, I would advise against using that. It never really worked as well as I was hoping, and I vaguely recall it will disappear altogether in the upcoming CMTK 2.3 release (which, sadly, isn't really making much progress right now).

This 
So for lack of better options, I would recommend computing one direction and then using the explicit (numerical) inversion for the other direction.
Just to give an example a test image reformatted with A->B or with the inverse of B->A took 30s and 1h15 respectively.
As for speed - if you need to apply the same inverse often, you can compute a deformation field using the xform2dfield tool, which also accepts the "--invert" option for each transformation you give it. This way, you invert the deformation once, sample it, and henceforth use the sampled version.
OK so I was starting to wonder about this. But what would i do to use the deformation field? Can it directly substitute for a standard parametric registration input for reformatx?
Another option, which isn't implemented yet unfortunately, would be to fit a B-spline to the inverse of whatever transformation you would like to invert. This was planned for the next CMTK release (did I mention it's not making much progress?)
I have also found the fit_spline_dfield. If I make a dfield (as above) can I then use this to fit a b-spline based parametric transform? Any tips for the whole procedure in this case?

Many thanks again,

Greg.
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TitleAuthorDate
Greg Jefferis Feb 8, 2013
Torsten Rohlfing Feb 8, 2013
RE: Inverse consistent bridging registrations
 Greg Jefferis Feb 9, 2013
Torsten Rohlfing Feb 10, 2013
Greg Jefferis Feb 11, 2013
Torsten Rohlfing Feb 11, 2013
Greg Jefferis Feb 12, 2013