Mukund Balasubramanian did something with barycentric coordinates to solve this problem, but I don't know whether he ended up publishing it or not.
On 03/30/2017 06:19 PM, Burke Rosen wrote: > I am interested in finding the distance between two vertices along the > cortical surface. > > So far I have used two methods: > > (1) Compute the shortest path with a variant of Dijkstra's algorithm > on the white surface. > > (2) Compute the great circle distance on the sphere surface. > (as done by Risk et.al <http://et.al>. 2016 Neuroimage) > > Method (1) is slow and will tend to overestimate distances as the path > only goes along mesh edges. > > Method (2) is very fast and gives a true geodesic but gives a scaled > result because the radius of sphere surface is arbitrary; also this > method is subject to distortions introduced by the inflation algorithm. > > My current strategy is to perform a linear regression between the > triangle face areas of the sphere and white surfaces. And then apply > the coefficients to the sphere surface diameter before calculating > geodesic distances. This yields a distance matrix with a similar > pattern to the Method (1) at about 62% scale. That scale seems like it > might be reasonable. However, the regression only explains ~58% of the > variance. My hunch is that the rest is due to inflation distortions. > > Is there a better way of scaling the sphere surface? Or a way to > inflate in such a way that inter-vertex distances are preserved? Or, > more generally, what is a good method of computing geodesic distances > on freesurfer surfaces. > > Thank you, > > Burke Rosen > > > _______________________________________________ > 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 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.
