[Mrtrix-discussion] voxel editing

[Donald Tournier]

Hi Kerstin,

Yes, mrview is not great for drawing ROIs. A better version is on my
to-do list...

There are often subtle alignment issues between the original image and
the overlaid ROI. The problem is that the software tries to fill in
the voxel at the current focus (crosshairs), and sometimes the
crosshairs are right on the border between two voxels, causing some
voxels to update and other not according to round-off. This can be
very hard to spot, since the focus is a point in 3D space, so
mis-alignment can happen through-plane. Try this:
- turn off interpolation (View->Interpolate)
- display the image in a different plane (i.e. go from axial to sagittal, etc)
- make sure the crosshairs are in the middle of a voxel
-  go back to the projection you were drawing on, and try to fill in
those voxels you were having trouble with.

Let me know if that doesn't help...
Cheers,

Donald.


On Tue, Nov 3, 2009 at 9:18 AM, Kerstin Pannek <k.pannek1 at uq.edu.au> wrote:
> sorry if you received this email twice...
>
> --------
>
> Hi all
>
> we are having some trouble drawing ROIs on a mouse brains here. That is,
> mrview allows us to only fill in or delete voxels in about 2 thirds of the
> imaging volume, with a sharp line between editable and uneditable voxels in
> the left-right direction.
> We tried on 64 bit Ubuntu Hardy and 32 bit Ubuntu Jaunty.
>
> Any help on this would be greatly appreciated.
>
> Cheers
> Kerstin
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> Mrtrix-discussion at www.nitrc.org
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>



-- 
Jacques-Donald Tournier (PhD)
Brain Research Institute, Melbourne, Australia
Tel: +61 (0)3 9496 4078