Thanks for the reply. Maybe I'm not thinking deeply enough about this, but since there is a 1-to-1 mapping from white to pial vertices, is there a possibility of self-intersection in the average?
-Keith On Sat, Apr 6, 2013 at 7:59 PM, Bruce Fischl <fis...@nmr.mgh.harvard.edu>wrote: > Hi Keith > > the average white/pial surface doesn't have any topological or smoothness > constraints, which is why we don't really use it. Yes, mris_expand is slow, > but that's precisely because it prohibits self-intersection. The good nes > is that compared to the rest of the recon stream it doesn't add that much > time :) > > Bruce > > > > On Sat, 6 Apr 2013, Keith Jamison wrote: > > I have seen that the official recommendation for making a mid-gray surface >> is to use mris_expand. This seems to be a very slow procedure on my >> machine. I have also tried just loading the ?h.white and ?h.pial surfaces >> into matlab, averaging their vertices, and exporting the result. This >> seems >> to result in a nearly identical surface as mris_expand. On a test >> subject, >> only 48 out of 127,998 (0.0375%) vertices differed by more than 0.1mm, and >> these were almost entirely around the edges of the corpus callosum. >> >> Is there a reason this alternative is a bad idea? I imagine mris_expand >> does additional topology checks along the way, but if the vertices vary so >> little, can that be a major problem? >> >> I'm inclined to go with the faster solution, but since I'm relatively new >> to >> this procedure, I wanted to see what the community's experience might be. >> >> Thanks! >> Keith >> >> ______________________________**_ >> Keith Jamison >> Graduate Research Assistant >> >> Department of Biomedical Engineering >> University of Minnesota >> 7-105 NHH, 312 Church St. SE >> Minneapolis, MN 55455 >> >> Office: 6-112 Nils Hasselmo Hall >> Mobile: 607-227-0696 >> kjami...@umn.edu >> >> >> >> > > 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<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. >
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