The conversions between tkrRas and scannerRAS are as following in Freesurfer:
tkrRAS = tkrvox2ras * inv(vox2ras) * scannerRAS scannerRAS = vox2ras * inv(tkrvox2ras) * tkrRAS
Best,
Yujing
From: freesurfer-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu On Behalf Of Eric Tsang Sent: Thursday, December 14, 2023 5:51 PM To: freesurfer@nmr.mgh.harvard.edu Subject: [Freesurfer] Convert Scanner RAS to Vertex RAS
External Email - Use Caution Dear All, I have great deal of trouble converting scanner RAS to vertex RAS. I have tried a couple of formula (in the following) which had failed to produce accurate coordinate.
[tkR tkA tkrS] = [ScannerRAS 1] / (vox2ras * inv(tkrvox2ras)) [tkR tkA tkrS] = [ScannerRAS 1] * inv(vox2ras0)
Both of these formula produced distorted coordinates. Please help!
Thanks, Tim