This is because it takes two passes through the transform. One takes each target vertex and finds the closest source vertex. The other takes each source vertex not already sampled and finds the closest target vertex to make sure that every source is represented. With the 2nd step, there may be some target vertices that have multiple sources, in which case the values are averaged, which is why you see some fractional values. You can add the flag --mapmethod nnf and see if that fixes it. "nnf" mean nearest-neighbor-forward (1st step) whereas the default is "nnfr" (both steps) where the r means "reverse"

On 5/11/2021 7:25 AM, Mason Wells wrote:

        External Email - Use Caution        

        External Email - Use Caution        

Hi experts,

I am trying to resample some surface overlays from fsaverage to fsaverage_sym surface. I have used the following command:

mri_surf2surf --srcsubject fsaverage --srcsurfreg fsaverage_sym.sphere.reg --trgsubject fsaverage_sym --trgsurfreg sphere.reg --hemi lh --sval lh.wang15_mplbl.mgz --tval lh.wang15_mplbl_fsaverage_sym.mgh 

However, the data in the overlay has changed. The original overlay contains whole values, whereas the resampled overlay on _sym surface contains decimal numbers also. I wondered if you could advise me on whether the command I am using is appropriate?

Best wishes,
Mason

Mason T Wells, MSc

PhD student

School of Optometry and Vision Sciences

& Cardiff University Brain Research

Imaging Centre (CUBRIC), School of Psychology

Cardiff University

Cardiff   

CF24 4HQ

UK

 

Email: WellsMT1@cardiff.ac.uk

Tel: 02920 879628

Web: Cardiff University webpage

Mason T Wells, MSc

Myfyriwr PhD

Yr Ysgol Optometreg a Gwyddorau’r Golwg

& Canolfan Ymchwil Delweddu’r Ymennydd Prifysgol Caerdydd (CUBRIC), Yr Ysgol Seicoleg

Prifysgol Caerdydd

Heol Maindy

Caerdydd   

CF24 4HQ 

DU

 

E-bost: WellsMT1@caerdydd.ac.uk

Ffôn: 02920 879628

 


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