I computed the region areas by adding the areas of the triangular faces inside these regions using the spherical coordinates of the vertexs and the Heron formula for the triangle area.
Another thing:
Should I use the sig.mgh file resulted from the mri_glm estimation as the input to the mri_surfcluster function in MonteCarlo simulations? (plus the .csd file of course).
In advance thank you a lot Jorge
--- Doug Greve greve@nmr.mgh.harvard.edu escribió:
How did you get the 15 mm^2 regions? And how did you know that they are 15mm^2? There are some complications with using the raw vertex areas on fsaverage. The total surface area of the average will be wrong (inevitable with the way that fsaverage is computed). However, there is a correction, and our tools take this into account.
doug
jorge luis wrote:
Hello all
I have made deep changes in 9 regions of a left hemisfere of a subject surface after maped it onto the fsaverage subject sphere. The changes were made
to
have areas close to 15 mm^2. I computed the areas
by
add the areas of the faces inside the regions (computed using the vertexes spherical
coordinates).
The freesurfer sphere mapping is based in minimal metric distortion, so, why I got the following differences?:
Region Computed areas (mm^2) Computed areas
(mm^2)
uing mri_surfcluster as explained beforewith the fsaverage sphere 1 27.56 15.0522 2 21.78 15.0946 3 21.41 15.1087 4 20.77 15.1501 5 19.28 15.1797 6 16.60 15.1918 7 15.99 15.2781 8 14.31 15.3373 9 13.89 15.0541
In both cases the same surface vertexes were found
to
be inside the regions
Another thing:
Should I use the sig.mgh file resulted from the mri_glm estimation as the input to the
mri_surfcluster
function in MonteCarlo simulations? (plus the .csd file of course).
In advance thank you a lot Jorge
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