Don, can you send your command line? If you are using surface-based registration, then the origin should not matter. You are right that there is not a one-to-one correspondence. The way it works  is that it starts on the target surface, goes through all the vertices and finds the closest vertex in the source and maps the value. At this point, each target only has one source, but each source may have multiple targets. By default, it then goes through another loop where it finds all the source vertices that have not been mapped, finds the closest target vertex, and  maps the source to that target (eventually taking the mean or sum of all the sources that map to a given target). If it is the 2nd stage that is giving you problems, then you can turn it off in mris_apply_reg with --nnf (stands for "nearest-neighbor-forward", vs the default nnfr where r=reverse).


On 12/3/2021 8:41 AM, Krieger, Donald N. wrote:

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Dear Bruce, Doug, and everyone,

 

  1. I am projecting labels from a subject’s labels onto the icosahedron and note that the mapping is not one-to-one. Because of this, I cannot tell which subject vertex maps to which icosahedron vertex which I need to able to do. What am I missing here?
  2. Just double-checking something simple – The center of the icosahedron is as the origin, i.e. 0,0,0, yes?

 

Thanks – Don

 


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