[Mne_analysis] mne_read_surfaces

[Daniel G Wakeman]

Hi Li Su,

The vertex number used is actually the index that one would use to identify the vertex in the .rr field. Therefore it is the FreeSurfer vertex number +1. Try examining the same three numbers -1 (each).

D
On 2010 Dec 29, at 22:08 , Li Su wrote:

> Dear MNE group,
> 
> Sorry to bother people during the Christmas and New Year break. I have a question about how to load the surface files in order to analyse triangulation information.
> 
> I use the mne_read_surfaces function in Matlab to load the surface information of the whole brain. As stated in the manual, it returns a structure with a field .tris, which indicates "vertex numbers of triangles in counter clockwise order as seen from outside". To valid if the vertices in each raw of this field are indeed forming a tiny triangle, I visualise them using mne_analyse with the same surface loaded.
> 
> Then, I performed a series of test by typing some random raws of the field of .tris in the bottom part of the GUI where it says "vertex # :". A tiny red cross appears on the surface marking out where the vertex is. I marked out all three vertices from the same raw of .tris. However, I was very surprised to see that these red crosses are way apart from each other and not forming a triangular shape!
> 
> I am not sure if I misunderstand what this triangulation information really means, or there is anything else I did wrong.
> 
> Many thanks for your answer and helps!
> 
> Li Su
> 
> --
> Li Su, PhD
> 
> MRC Cognition and Brain Sciences Unit
> 15 Chaucer Road
> Cambridge CB2 7EF
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> 
> Phone +44 1223 273632 (direct line)
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