Re: [Freesurfer] distance comparisons across subjects in fsaverage group sphere

2014-05-13 Thread Rudolph Pienaar
Von: freesurfer-boun...@nmr.mgh.harvard.edu [freesurfer-boun...@nmr.mgh.harvard.edu]quot; im Auftrag von quot;Bruce Fischl [fis...@nmr.mgh.harvard.edu] Gesendet: Montag, 12. Mai 2014 15:46 An: Freesurfer support list Betreff: Re: [Freesurfer] distance comparisons across

[Freesurfer] distance comparisons across subjects in fsaverage group sphere

2014-05-12 Thread Milde, Christopher
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

Re: [Freesurfer] distance comparisons across subjects in fsaverage group sphere

2014-05-12 Thread Bruce Fischl
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

Re: [Freesurfer] distance comparisons across subjects in fsaverage group sphere

2014-05-12 Thread Milde, Christopher
...@nmr.mgh.harvard.edu]quot; im Auftrag von quot;Bruce Fischl [fis...@nmr.mgh.harvard.edu] Gesendet: Montag, 12. Mai 2014 15:46 An: Freesurfer support list Betreff: Re: [Freesurfer] distance comparisons across subjects in fsaverage group sphere Hi Christopher the spherical mapping usually has

Re: [Freesurfer] distance comparisons across subjects in fsaverage group sphere

2014-05-12 Thread Bruce Fischl
An: Freesurfer support list Betreff: Re: [Freesurfer] distance comparisons across subjects in fsaverage group sphere 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