Hi Christopher
the spherical mapping usually has on the order of 17-20% distortion in
distances, and the registration is probably significantly more. I'm not
entirely sure what are trying to do, but you can measure the difference in
great circle length between the sphere and sphere.reg to get an idea of how
much additional distortion is induced by the registration
cheers
Bruce
On Mon, 12 May 2014, Milde, Christopher wrote:
Dear Freesurfers,
In Fischl et al. 1999 it is highlighted, that the topological structure of the
original
surface is preserved in the spherical space and due to the nature of a sphere,
computations
(distance, area) measures are easy to make.
My question now, concerns the comparability of distance measures between
subjects in the
group fsaverage sphere. My aim is to compare distances between peak voxels
coordinates of
two study populations, to figure out if a systematic difference exist between
the peak voxel
distances of the two study populations.
Can I compare the distances between peak voxels (vertices) between different
subjects based
on the fsaverage group sphere? So, is the comparability of distances between
vertexes of
individually spheres preserved in group fsaverage space?
Ps: I know that the distances in spherical space are not Euclidian but still
geodesic
Best wishes and thanks in advance,
Christopher Milde, M.Sc. Biol.
Institute for Cognitive and Clinical Neuroscience
Central Institute of Mental Health Square J 5
68159 Mannheim, Germany
Christopher Milde, M.Sc. Biol.
Institute for Cognitive and Clinical Neuroscience
Central Institute of Mental Health Square J 5
68159 Mannheim, Germany
Phone: +49-621-1703-6313
E-mail: christopher.mi...@zi-mannheim.de
Homepage: http://www.zi-mannheim.de/
Office: Forschungs- und Verwaltungsgebäude, Room 230
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