Dear Don,
There is no way to get the new format at the moment because we haven't
made the final decisions yet. In any case, it'll still be the same kind
of binary file with Matlab header file, just the header will be
different.
So for now you should still use the spec from the manual. D.units field
is just for display so id doesn't really affect anything. However if
your data is in Tesla, i.e. numbers with order of magnitude of 10e-15
they won't display properly and there might be other problems since such
numbers seem to Matlab to be almost zero. So I'd recommend to work with
numbers around 1-10 and set the units accordingly.
Another problem we are presently discussing internally is that SPM does
not represent MEG gradiometers correctly and SPM5 source reconstruction
is only correct for CTF data recorded with 'raw' setting. I'm not sure
what kind of montage you have in BTi, but if you have things like 3rd
gradient or planar gradiometers I'd be extra-careful. Feel free to play
around but please send us the details before you try to publish
anything. Most of these problems will hopefully be resolved in SPM8.
Best,
Vladimir
-----Original Message-----
From: Rojas Don [mailto:[log in to unmask]]
Sent: Thursday, January 03, 2008 10:31 PM
To: Vladimir Litvak
Subject: Re: [SPM] SPM5 MEG scaling
Dear Vladimir,
Thanks for the heads up on the new format. Reading the format (4D
Neuroimaging, aka Bti) isn't an issue. We already have matlab code to
directly read the binaries without the bothersome step of exporting from
the
4D database using Christian Wienbruch's tool (which is how I understand
Fieldtrip and SPM currently read this format). I just need to know the
format spec for SPM, which I guess is going to change in SPM8. Is there
somewhere I can get hold of the new format, and will it be similar to
the D
structure in SPM5?
Thanks,
Don
On 1/3/08 1:13 PM, "Vladimir Litvak" <[log in to unmask]> wrote:
> Dear Don,
>
> The old style converters are about to be deprecated and SPM EEG format
> will be changed for SPM8. Thus, the best way to contribute a reader to
> SPM is to implement it in a format compatible with the fileio
interface
>
http://www2.ru.nl/fcdonders/fieldtrip/doku.php?id=fieldtrip:development:
> fileio that is now shared between Fieldtip and SPM and will be the
only
> conversion tool for SPM8. Once you implement it this way, it'll also
> work with 'Generic conversion' option already available in SPM5. You
> should actually check whether the format you mentioned is not
supported
> there already at least to some extent.
>
> If you need more help, please write me directly.
>
> Best,
>
> Vladimir
>
> -----Original Message-----
> From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]]
> On Behalf Of Rojas Don
> Sent: Thursday, January 03, 2008 5:25 PM
> To: [log in to unmask]
> Subject: [SPM] SPM5 MEG scaling
>
> Dear SPMers:
>
> I'm writing a conversion tool to convert an MEG binary format directly
> into
> SPM5 format. Must the scaling be in femtoTesla for the D.units field
> and
> corresponding data binary, or can it be units of Tesla?
>
> Thanks in advance!
>
> Don Rojas
> University of Colorado School of Medicine
> Denver USA
>
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