Hi Ben, there are several things going on/wrong here. tksurfer reports the coords from the orig surface (historical reasons) which will be slightly different than the white surface in most casesand somewhat different than the pial. These coordinates are in our special coordinate system and not scanner RAS. To get RAS, see http://surfer.nmr.mgh.harvard.edu/fswiki/CoordinateSystems
doug On 02/28/2013 02:21 PM, Brinkmann, Benjamin H., Ph.D. wrote: > > Dear FreeSurfers, > > I am working on generating a functional map of electrophysiological > activity on a freesurfer pial surface and I've come across something > that has stumped me. I have the electrode coordinates in RAS space and > I am trying to interpolate a value at each surface vertex for the > color map using the RAS coordinate of each vertex. However, the RAS > coordinates I read into matlab using freesurfer_read_surf.m are > different from what is being displayed in tksurfer. (I'm comparing RAS > coordinates by hovering the cursor in tksurfer.) Most of the time the > differences are very small, but occasionally they can be large. I > haven't been able to identify any kind of a constant offset or > relationship between these coordinates. > > Should the RAS coordinates displayed in tksurfer be the same as what > is read directly from the surface file? Is there a better way to > approach this task? > > Thanks very much for any suggestions. > > Regards, > > Ben Brinkmann > > > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > Benjamin H. Brinkmann, PhD > Mayo Systems Electrophysiology Lab > Alfred 9-441C, SMH > 1216 Second St. SW > Rochester, MN 55902 > > > > _______________________________________________ > 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: 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.
