[FieldTrip] 4d data reading (248 sensor MEG system)

Mehmet-Akif Coskun mcoskun at mail.uh.edu
Thu Mar 10 19:35:39 CET 2011

Hi Jan,

   Thanks for the reply. I tried reading from the raw data as suggested in the link and i always getting an error like below.


?? Error using ==> fseek
Offset must be of class double

Error in==> fileio\private\read_4d_hdr_at_183
         fseek(fid,nbytes2 - 32, 'cof');

Error in ==> ft_read_header_at_246
       orig                   = read_4d_hdr(datafile,configfile)

the data that i try to read is raw data (unprocessed) but still i can't read. Previously i was trying the data that has been processed to remove environmental noise in 4d meg system sofware, and that didnt work too.

Which part i am missing?


----- Original Message -----
From: jan-mathijs schoffelen <jan.schoffelen at donders.ru.nl>
Date: Thursday, March 10, 2011 2:46 am
Subject: Re: [FieldTrip] 4d data reading (248 sensor MEG system)
To: Email discussion list for the FieldTrip project <fieldtrip at donders.ru.nl>


> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip|

> Hi Mehmet,

> Please have a look at http://fieldtrip.fcdonders.nl/getting_started/bti.

> I would not recommend the .xyz/.m4d variant, but would directly read from the raw data files. Support for .xyz/.m4d files (these files contain relevant header information) is implemented in fieldtrip just for backward compatibility. These need to be created from the raw data (using the pdf2set command (see the software manual of the MEG-system for reference)), but contain only limited header information (e.g. the balancing coefficients are not extracted). To me this sounds like double work, because FieldTrip can read the header information from the raw files directly.

> Good luck,

> Jan-Mathijs




> On Mar 10, 2011, at 6:36 AM, Mehmet-Akif Coskun wrote:> 
> Hello Dear Fieldtrip users,
>        I am a newbie in fieldtrip. I am having trouble reading the 4d data in fieldtrip. We are using a 248 sensor 4D MEG system. I have followed the discussion list and tried the suggestions but haven't succeeded reading the data. As far as i understand, i need some files (.xyz and .m4d) to be able to read the data but i don't also know how to obtain these files. Can anyone explain me the steps that i need to follow?
> Thanks in advance,
> Mehmet
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip

Dr. J.M. (Jan-Mathijs) Schoffelen 

> Donders Institute for Brain, Cognition and Behaviour, 
> Centre for Cognitive Neuroimaging,
> Radboud University Nijmegen, The Netherlands

> J.Schoffelen at donders.ru.nl

> Telephone: 0031-24-3614793> > 

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