Date: 2013-11-27 23:09
Sender: Torsten Rohlfing
The root of the problem is that affine matrices with non-zero shear
were not created correctly. Thus, scale factors and shear
coefficients could then not unambiguously recovered.
This also applies to transformations without shear, but anisotropic
scale, if these were inverted (thus introducing shear in the
inverse transformation).
Most previously-computed transformations should be correct, with
the exception of transformations fitted to landmarks or computed
using principal axes (these create the matrix directly, then derive
canonical parameters).
SVN trunk r5048 should fix all this in the following way:
- Newly-created transformations are now (hopefully) correct - this
required a re-definition of the meaning of shear coefficients (also
more logical now).
- Exiting transformation parameter files will continue to be read
and create the same matrix representation as before (although that
representation may be flawed; see above).
- New transformation files will look identical to old ones but use
a different meaning of the "shear" coefficients. To distinguish old
from new files, the release code in the first line of the
transformation files has been changed from "1.1" to "2.4", thus
showing that the respective files require at least CMTK 2.4 to be
read correctly.
THIS HAS NOT YET BEEN THOROUGHLY TESTED, so r5048 should NOT be
used in production mode just yet! (This bug will be left open until
I am confident that this is now properly working.)
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