Just checked mris_euler_number, holes are calculated from euler number: holes
= 1-eno/2
From: freesurfer-boun...@nmr.mgh.harvard.edu
<freesurfer-boun...@nmr.mgh.harvard.edu> On Behalf Of Fischl, Bruce R.,PHD
Sent: Thursday, February 1, 2024 10:27 AM
To: Freesurfer support list <freesurfer@nmr.mgh.harvard.edu>
Subject: Re: [Freesurfer] Euler number calculation from number of holes
Hi Melissa
mris_euler_number <surface>
writes out a bunch of stuff, including the Euler number:
mris_euler_number ~/links/subjects/bruce.dev/surf/lh.orig.nofix
euler # = v-e+f = 2g-2: 154526 - 463668 + 309112 = -30 --> 16 holes
F =2V-4: 309112 != 309052-4 (-64)
2E=3F: 927336 = 927336 (0)
total defect index = 32
so -30 in this case. Is that what you wanted?
Cheers
Bruce
From:
freesurfer-boun...@nmr.mgh.harvard.edu<mailto:freesurfer-boun...@nmr.mgh.harvard.edu>
<freesurfer-boun...@nmr.mgh.harvard.edu<mailto:freesurfer-boun...@nmr.mgh.harvard.edu>>
On Behalf Of Melissa Thalhammer
Sent: Thursday, February 1, 2024 5:31 AM
To: Freesurfer@nmr.mgh.harvard.edu<mailto:Freesurfer@nmr.mgh.harvard.edu>
Subject: [Freesurfer] Euler number calculation from number of holes
External Email - Use Caution
Dear FreeSurfer experts,
I want to calculate Euler numbers for QC but I am not sure how to get them. I
read some posts here and figured out that I get the number of holes in a
surface with mris_euler_number -o $OUTPUT_FILE $subject/surf/?h.orig.nofix. Is
it correct that I need to calculate the Euler number subsequently as the sum of
holes of both surfaces and then Euler_number=(number_of_holes*(-2)) -2 ?
Best, Melissa
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