I don't have a core paper on the area mapping (which is more complicated than mapping thickness). Anderson Winkler wrote a paper on the subject, but we are not using his method. Our method is relatively simple. Each vertex in fsaverage is mapped back to the individual to find the closest vertex. The thickness or area at this vertex is then assigned to the vertex in fsaverage. There will be some fsaverage vertices that map to the same vertex in the individual. For thickness, this is not a problem. For area or volume, we divide the value by the number of fsaverage vertices that share the individual vertex to preserve the total. This may leave some vertices in the individual that were never a closest vertex. We loop through these vertices and do a reverse map back to fsaverage to find the closest vertex. These fsaverage vertices will then have multiple vertices from the individual. For thickness, we compute the mean of the source vertices. For area or volume we compute the sum (must preserve the total).
make sense? doug On 01/16/2015 12:00 AM, Bronwyn Overs wrote: > I meant that as well as the mapping of the area to the average space. > > Kind regards, > > Bronwyn Overs > Research Assistant > > Neuroscience Research Australia > > Neuroscience Research Australia > Margarete Ainsworth Building > Barker Street Randwick Sydney NSW 2031 Australia > *M* 0411 308 769 *T* +61 2 9399 1883 *F* +61 2 9399 1265 > > neura.edu.au <http://neura.edu.au> > > Follow @neuraustralia on twitter > <https://twitter.com/neuraustralia>Follow NeuRA on facebook > <https://www.facebook.com/NeuroscienceResearchAustralia>Subscribe to > the NeuRA Magazine <http://www.neura.edu.au/help-research/subscribe> > > On 16/01/2015 3:58 pm, Douglas Greve wrote: >> >> The computation is pretty simple, it is just the average of the area >> of the surrounding triangle. Is that what you mean or do you mean the >> mapping of said area to the average space? >> doug >> >> >> >> On 1/15/15 11:37 PM, Bronwyn Overs wrote: >>> Dear Mailing List, >>> >>> I would like to understand how freesurfer calculates the surface >>> area at each voxel to be used in the GLM procedure. Is there a key >>> methods paper that describes this process, and can this method be >>> explained in simple terms? >>> -- >>> >>> Kind regards, >>> >>> Bronwyn Overs >>> Research Assistant >>> >>> Neuroscience Research Australia >>> >>> Neuroscience Research Australia >>> Margarete Ainsworth Building >>> Barker Street Randwick Sydney NSW 2031 Australia >>> *M* 0411 308 769 *T* +61 2 9399 1883 *F* +61 2 9399 1265 >>> >>> neura.edu.au <http://neura.edu.au> >>> >>> Follow @neuraustralia on twitter >>> <https://twitter.com/neuraustralia>Follow NeuRA on facebook >>> <https://www.facebook.com/NeuroscienceResearchAustralia>Subscribe to >>> the NeuRA Magazine <http://www.neura.edu.au/help-research/subscribe> >>> >>> >>> >>> _______________________________________________ >>> Freesurfer mailing list >>> Freesurfer@nmr.mgh.harvard.edu >>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >> >> >> >> _______________________________________________ >> 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. > > > > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer -- Douglas N. Greve, Ph.D. MGH-NMR Center gr...@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422 Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
