Dear Thomas,
Looking at the file rh.sphere.asc, it seems that the problem comes from
the spherical registration that generates a spherical surface with, as
you said, small triangles slightly overlapping.
However, these distortions should be extremely small. If you really need
to get rid of them, one hacky solution would be to detect these (small)
regions and to smooth them untill the overlapping edges(faces) disappear.
Since these regions are small, this should not generate large
metric distortions.
But maybe Bruce has some other ideas.
Florent
-------------------------------------
Florent Segonne
PhD Candidate
Stata Center 32-D430 CSAIL MIT
1 617 253 2986
http://people.csail.mit.edu/~fsegonne
-------------------------------------
On Thu, 10 Nov 2005, Thomas, Adam (NIH/NIMH) wrote:
I recently noticed that some of my subject's spherical surfaces appears
to have several small, pyramid-like points on them. One example is shown
here in tksurfer:
http://fmrif.nimh.nih.gov/~adamt/sphere.jpg
Looking at these points in more detail in suma shows that several
triangles are folder on top of each other so that all the vertices are
on the spheres surface, but some triangles are entirely overlapped by
others.
The spherical surface is here:
http://fmrif.nimh.nih.gov/~adamt/rh.sphere.asc (11MB)
And this is a close up of near node 141619 in suma:
http://fmrif.nimh.nih.gov/~adamt/sphere_suma_zoom.jpg
These distortions are causing us problems with subject averaging. Is
there something we can do to fix or avoid them?
Thanks,
-Adam
---
Adam Thomas [EMAIL PROTECTED]
Functional MRI Facility, NIMH/NIH/DHHS
10 Center Dr, Room B1D708A
Bethesda MD. 20892-1148
Phone:301-402-6351 Fax: 301-402-1370
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