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Hi short note aside: if at all possible, you should register from low to highres and then invert (using convert_xfm) the transformation (rather than registering highres to lowres directly). Always use the 'better' image as reference, that will improve accuracy. best christian On 25 Nov 2003, at 01:17, Hoang Tran wrote: > Hi Mark, > > We ran into the FLIRT 5.0 segmentation violation issue on RedHat 9. The > images that cause the problems are located at: > > http://www.nbresearch.com/data/FlirtSegViolationImages.zip > > This file contains two sets of images: T1 (high resolution) and ref-T1 > (low > resolution) > > > The command that we used which triggers the segmentation error is: > > flirt -in T1 -ref ref-T1 -out foo > > The interesting thing is that the problem doesn't occur for every T1 > image > we have and it only occurs when trying to register the higher > resolution T1 > image to the lower resolution reference image. > > In any case, running with verbose set at a high level shows that the > problem always occurs just after: > >>> copy U UE >>> if MAXDOF > 9 >>> clear U >>> if MAXDOF > 9 >>> optimise 12 UE:1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 rel 2 > Coarse rotation samplings are: > -1.570796 -0.523599 0.523599 1.570796 > -1.570796 -0.523599 0.523599 1.570796 > -1.570796 -0.523599 0.523599 1.570796 ... > > If any further information to debug the problem is needed, then please > let > me know. > > -Hoang > -- Christian F. Beckmann Oxford University Centre for Functional Magnetic Resonance Imaging of the Brain, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK Email: [log in to unmask] - http://www.fmrib.ox.ac.uk/~beckmann/ Phone: +44(0)1865 222782 Fax: +44(0)1865 222717