The head points file (.hpts) is just a file of lines containing a
label, an index, and an xyz coordinate:
cardinal 2 0.00 0.112500 0.00
cardinal 3 0.071534 0.00 0.00
hpi 1 0.068430 0.020674 0.088621
hpi 2 0.040329 -0.083517 0.094487
hpi 3 -0.041193 -0.079972 0.100122
hpi 4 -0.054395 0.032501 0.102959
extra 1 0.72 0.111427 0.58
extra 2 0.070781 0.000371 0.000230
extra 3 -0.072046 -0.000394 -0.000207
extra 4 0.067647 0.020419 0.088373
...
The transform file (.trans) is a 4x4 float matrix:
9.999452e-01 -1.047178e-02 0.00e+00 -4.73e+00
1.044092e-02 9.969981e-01 7.671904e-02 -1.033253e+01
-8.033852e-04 -7.671483e-02 9.970528e-01 -6.399206e+01
0.00e+00 0.00e+00 0.00e+00 1.00e+00
I don't know of anybody who actively uses the head point stuff, so I'm
not sure if it's up to date with how you generated the data.
On Fri, Oct 27, 2006 at 11:16:04AM -0500, Juranek, Jenifer wrote:
Hi,
What are the file format requirements for the 2 files called to load
head points - *.hpts and *.trans into tkmedit or tksurfer?
We have a whole-head neuromagnetometer (4-D Neuroimaging 3600 Magnes MEG
system) with 248 sensor channels.
I'd like to co-register my dipole locations with FreeSurfer's
aseg+aparc.mgz to efficiently localize dipoles x ROIs. I have already
co-registered index points and headshape files to each subject's aMRI
within 4D's software.
Any advice is greatly appreciated!
Jenifer
--
Kevin Teich
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