Thanks, Bruce! -David

On Tue, Sep 10, 2013 at 5:46 AM, Bruce Fischl fischl@nmr.mgh.harvard.eduwrote:

Hi David

there are situations in which mri_pretess can elimate pathological configurations by removing/adding any one of a set of voxels. In those cases the norm is used to decide among them (e.g. to remove the one that appears least like WM or to add the one that appears most like WM)

cheers Bruce

On Mon, 9 Sep 2013, David Romano wrote:

Hi everyone,

...

I was hoping that someone could clarify for me the role played by norm.mgz in the command

mri_pretess filled.mgz 255 norm.mgz filled-pretess255.mgz

from the -tessellate step of the -autrecon2 section on the page

http://surfer.nmr.mgh.harvard.**edu/fswiki/ReconAllDevTablehttp://surfer.nmr.mgh.harvard.edu/fswiki/ReconAllDevTable .

My understanding is that this command will (roughly) perform the following tasks for a given voxel v in filled.mgz with intensity 255:

1. Determine whether there are any other voxels of intensity 255 in the

3x3x3 cube centered at v.

2. If so, then further determine whether none of these share a face with

v.

3. If so, then let S be the set of all such voxels, together with v

itself, and identify an "optimal" collection of the remaining voxels in the 3x3x3 cube to add to S so that every voxel in S shares a a face with at least one other voxel in S, where "optimal" means that the added voxels should have intensities as close as possible to 255 in norm.mgz.

Does this capture the role played by norm.mgz? Or am I way off?

Thanks in advance for your help, David Romano

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