Vladimir,
I'm happy to share whatever I come up with. I've imported several of my
datasets, from a 248 channel 1st order gradiometer system, using the spm8
convert routine to compare to my own function. I notice that there are a
number of errors with respect to the channels and other aspects of the spm8
converted files. For example, in the 4D headframe, +x is anterior and +y is
left. So, in my own converter function, which I'm glad to forward if anyone
is interested, the x and y from the 4D are swapped and the 4D +y becomes -y
before the swap (all assuming that spm represents +y anterior and +x right,
which is how I read the coordinates from the EEG templates and example
files. I am using Eugene Kronberg's pdf4D object to perform the reading
from the 4D raw files. I believe that his code has been incorporated into
Fieldtrip, but I'll need to dig into the convert code in spm8 to see what's
going on. I'm not a Fieldtrip user myself, so I cannot say for certain how
it incorporates Eugene's code.
Best,
Don
On 11/11/08 2:26 PM, "Vladimir Litvak" <[log in to unmask]> wrote:
> Dear Don,
>
> SPM is perfectly capable of converting 4D-BTi format. Perhaps you
> should just try the 'Convert' button. As I remember you have a lot of
> experience with converting BTi data so perhaps you can contribute to
> SPM8 (and also Fieldtrip) by contributing to the BTi readers included
> in the fileio toolbox. Robert Oostenveld and Jan-Mathijs Schoffelen
> (in CC) would be the key people to talk to about this. But perhaps you
> should start with checking out the existing functionality.
>
> You can also find additional information at:
>
> http://www2.ru.nl/fcdonders/fieldtrip/doku.php?id=fieldtrip:development:fileio
> http://www2.ru.nl/fcdonders/fieldtrip/doku.php?id=fieldtrip:documentation:freq
> uently_asked_questions#how_are_electrodes_magnetometers_or_gradiometers_descri
> bed
>
> Best,
>
> Vladimir
>
> Robert Oostenveld" <[log in to unmask]>
>
> On Tue, Nov 11, 2008 at 8:05 PM, Rojas Don <[log in to unmask]> wrote:
>> Dear list,
>>
>> I am putting the finishing touches on a converter for the 4DNeuroimaging
>> Magnes MEG system into the new SPM8 format and have a couple of questions:
>>
>> 1) How does the format represent the sensor geometry (i.e., magnetometer,
>> gradiometer, planar gradiometer)?
>>
>> 2) What does the tra field in D.sensors.meg represent?
>>
>> I'll probably have a few more, but I thought I'd start with those.
>>
>> Best,
>>
>> Don Rojas
>>
>> --
>> Donald C. Rojas, Ph.D.
>> Associate Professor of Psychiatry and Neuroscience
>> Director, Magnetoencephalography Laboratory
>> University of Colorado Denver
>> Department of Psychiatry, Mail Stop F-546
>> Anschutz Medical Campus, Building 500 N2224G
>> 13001 E 17th Place
>> PO Box 6508
>> Aurora CO 80045-0508
>> 303-724-4994
>> [log in to unmask]
>>
>> Please note: My email address has changed from [log in to unmask] to
>> [log in to unmask] Please update your records.
>>
--
Donald C. Rojas, Ph.D.
Associate Professor of Psychiatry and Neuroscience
Director, Magnetoencephalography Laboratory
University of Colorado Denver
Department of Psychiatry, Mail Stop F-546
Anschutz Medical Campus, Building 500 N2224G
13001 E 17th Place
PO Box 6508
Aurora CO 80045-0508
303-724-4994
[log in to unmask]
Please note: My email address has changed from [log in to unmask] to
[log in to unmask] Please update your records.
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