[MINC-users] minctracc bug in lattice generation

[Alex Zijdenbos]

On Tue, Nov 11, 2014 at 12:23 AM, Andrew Janke <a.janke at gmail.com> wrote:

> On 11 November 2014 14:21, Alex Zijdenbos <zijdenbos at gmail.com> wrote:
> > I stumbled across a fairly significant bug in minctracc's lattice
> > generation. In short, the world coordinates of the deformation field that
> > it generates are wrong, especially when the input volume(s) contain
> > non-standard direction cosines.
>
> Does a test case with no direction cosines look similar but to a
> lesser degree?  I have probably struck this before with grid files for
> use in model generation but got around things by using an approach
> like this:
>
>    https://github.com/BIC-MNI/minc-widgets/blob/master/gennlxfm/gennlxfm
>
> That is, I always give minctracc an input xfm in order to determine
> the bounds of the output xfm.
>

I see. No - if the volume(s) have no direction cosines, the 'drift' in the
deformation grid lattice does not happen (at all). In that case the only
problem is that the grid is not perfectly centered on the (target?) volume,
but it stays in place during multiple calls to minctracc.

By the way, if the target volume does have direction cosines, they are
inherited by the xfm, and they themselves don't change through multiple
minctracc invocations.

-- A