That almost works; tkmedit is giving talairach coordinates of, for a few
examples:
14.7 23.9 -22.3
24.8 21.9 -18.8
35.6 20.8 -20.9
54.2 14.1 -17.1
61.1 10.9 -9.6
62.3 6.0 -1.8
Running mri_label2label with fsaverage as the target subject yields a label in
which those same points have the coordinates:
14.877 25.802 -25.101
25.004 23.475 -20.993
35.985 22.497 -23.559
54.764 15.410 -19.482
61.693 11.670 -10.781
62.952 6.235 -1.732
For comparison purposes, the RAS coordinates in the original label are:
12.000 43.000 5.000
21.000 41.000 9.000
31.000 41.000 7.000
48.000 35.000 11.000
54.000 31.000 19.000
55.000 25.000 27.000
And talairach.xfm is:
1.1105 0.0582 0.0623 -0.1394
-0.0761 1.0376 0.1083 -21.5909
-0.0404 -0.0732 1.0813 -26.6708
Multiplying those RAS coordinates by the given talairach transformation gives
coordinates of:
16.0028 22.6522 -24.8958
26.1303 20.3252 -20.7878
37.1110 19.3473 -23.3543
55.8898 12.2610 -19.2767
62.8184 8.5205 -10.5760
64.0778 3.0855 -1.5270
The three sets of values are close, but not the same. The discrepancy is really
making me uncomfortable; any ideas what's going on?
Thanks so much,
Jed
On Jul 22, 2011, at 5:39 PM, Douglas N Greve wrote:
>
> You're so close! Use fsaverage as the target subject. The output
> coordinates will be in MNI305 space.
> doug
>
>
>
> Jed Singer wrote:
>> I'm at my wits' end with what seems like it should be an easy question. I
>> have a lot of volume labels that have been saved for a lot of brains. I want
>> the Talairach coordinates corresponding to those points. It seems like
>> mri_label2label should be able to do this, by putting in 'talairach' as the
>> target subject, but this returns an error that the subject 'talairach' isn't
>> found:
>>
>> mri_label2label --srcsubject m00045 --srclabel label/all.label --trgsubject
>> talairach --trglabel all_talairach.label --regmethod volume
>>
>> It seems like I should be able to do it manually by loading the
>> talairach.xfm generated by recon-all and multiplying that matrix by the RAS
>> points in the labels; this yields results that are pretty close to those
>> given in tkmedit, but not that close. Usually within a few, sometimes off by
>> more.
>>
>> Probably my inability to do this reflects some misunderstanding or lack of
>> information, but I've been poring over documentation, forum, and wiki for
>> hours now and feel like I've hit a wall. Any suggestions?
>>
>> Thanks so much,
>> Jed
>> _______________________________________________
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