Hi Pam,

1. The variance downweights features that are variable across subject, and let’s the registration depend on more stable features like central/calcarine/sylvian in a smooth manner.
2. The surfaces for a given hemisphere all have the same topology (# of vertices,edges,faces) and vertex index is preserved, so it is trivial to look up the “same” vertex on the different surfaces.

Make sense?

Cheers

Bruce

From: freesurfer-bounces@nmr.mgh.harvard.edu <freesurfer-bounces@nmr.mgh.harvard.edu> On Behalf Of Pam Garcia
Sent: Thursday, September 24, 2020 1:03 AM
To: freesurfer@nmr.mgh.harvard.edu
Subject: [Freesurfer] parameterization template and the vertex correspondence in the pial surface

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Hi FreeSufer team.

I have some questions related to the parameterization template and the vertex correspondence in the pial surface.

1. In the parameterization template what is the reason for using the mean and variance of curvature for WM surface using the inflated and smoothed surface? What independent information do these measures supply?  

2. Related to the vertex correspondence. How is the spherical surface mapped to the pial surface to achieve vertex correspondence between the WM and pial surfaces?

Thanks a lot for the responses

best

Pam