Hi Christian, thanks for the reply.
It makes sense there is not a one-to-one mapping.
However, the coordinates presented in the spm Results GUI (see attached png), when viewing the surface data results, seem to correspond to MNI coordinates. Is this a rough estimation of surface to voxel coordinates?
Is there a way to pull the surface data out at those reported clusters?
Tyler
-----Original Message-----
From: SPM (Statistical Parametric Mapping) <[log in to unmask]> On Behalf Of Christian Gaser
Sent: Wednesday, February 17, 2021 7:19 PM
To: [log in to unmask]
Subject: Re: [SPM] MNI voxel coordinates to Surface Vertices
[External Email]
Dear Tyler,
it is not possible to make a one-to-one mapping from voxel to surface coordinates. Imagine how the surface intersects or crosses a 3D volume, therefore the connection between voxel and vertex is not always possible.
Best,
Christian
On Wed, 17 Feb 2021 14:01:20 +0000, Fettrow,Tyler <[log in to unmask]> wrote:
>Hi all,
>
>I am new to playing with the surface data so I may not be using the terminology properly and apologize in advance. I am trying to figure out how to extract data from specific points from a gifti surface file created by CAT12. Specifically, I would like to convert an MNI coordinate to vertices, or the entry type that is necessary to extract data from the surface files.
>
>Digging through cat_surf_results I see on line 3310 "y = spm_data_read(SPM.xY.VY, 'xyz', XYZ)", which grabs the data from the cursor position of the CAT Results GUI. Is it possible to convert from voxel coordinates to this expected ordered vector of vertices? Is there a function embedded in the CAT12 library that does this already, for example, within the ROI analysis portion of CAT12?
>
>Thanks for any feedback.
>
>Tyler
>
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