Hi Lars, I guess you are working with vertexwise rather than facewise data, is this right? You'd need to compute then the area-per-vertex of the same sphere used as the target for the interpolation, i.e., the ico7 (surf/?h.sphere.reg in fsaverage I think). Attached is a Matlab function that calculates this area-per-vertex (or the area-per-face )from a surface and saves as a curvature file, in ASCII format. It reads also in ASCII, so you need to convert first (mris_convert). To run, it's something as this:
*srf2area lh.sphere.reg.srf ico7.area.dpv dpv* Then multiply either each subject area map (after interpolation), or the average map, by 4*pi*r^2 (r should be 100), and divide the result by the area-per-vertex from the sphere that you calculated above, and divide the result again by the number of vertices in the sphere, which should be 163842. To do this, use the attached rpncalc function, that also runs in Matlab, and does simple maths in curvature files that are all of the same size, using RPN notation <http://en.wikipedia.org/wiki/Reverse_Polish_notation>. Inputs are also in ASCII. To run, it should be something like this: rpncalc lh.white.interp.dpv 125663.706144 * ico7.area.dpv / 163842 / lh.white.interp.corrected.dpv The output you can convert back to cuvature binary and load with tksurfer or FreeView. Hope this helps! All the best, Anderson On 1 June 2014 16:32, Lars M. Rimol <lari...@gmail.com> wrote: > > Hi Anderson, > > Thank you! How would you suggest I address this issue when I smooth these > images before statistical analysis? I normally use the smoothing algorithm > implemented in FreeSurfer (mri_surf2surf). > > > > > -- > yours, > > Lars M. Rimol, PhD > St. Olavs Hospital > Trondheim, > Norway > > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > > The information in this e-mail is intended only for the person to whom it > is > addressed. If you believe this e-mail was sent to you in error and the > e-mail > contains patient information, please contact the Partners Compliance > HelpLine at > http://www.partners.org/complianceline . If the e-mail was sent to you in > error > but does not contain patient information, please contact the sender and > properly > dispose of the e-mail. > >
srf2area.m
Description: Binary data
rpncalc.m
Description: Binary data
_______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
