Hi Rey,

 

Thank you for the report. I tried with my workstation (CentOs) but I was not able to reproduce the problem.

Using “–st 4 –movecomp” and “-st 4 –movecomp –hpoie 10 –hpig 0.9” produced exactly the same outcome, and there were no replicated chunks. For debugging, I need some more information:

1.      What is your operating system (which Linux)?

2.      Does the bug happen with every file you are processing?

3.      Please send a maxfilter output log for inspecting the details.

4.      Can you send me a datafile (original data) and the exact command line you used?

 

Best regards, Jukka

 

P.S. Please report these kinds of problems also to [log in to unmask]. 

 

 

Jukka Nenonen | Method Development Manager Elekta Oy Box 34, FI-00531 Helsinki, Finland Visiting Address: Siltasaarenkatu 18-20 A, Helsinki Office: +358 9 756 24085 | Mobile: +358 400 249 557 | Fax: +358 9 756 24011 [log in to unmask] | www.elekta.com

 

From: Announcement for the Neuro MEG list [mailto:[log in to unmask]] On Behalf Of Rey Ramirez
Sent: 14. toukokuuta 2014 3:52
To: [log in to unmask]

Subject: MaxFilter hpie and hpig bug produces repetition of data sequences, and solution

 

Dear Jukka, Samu, and colleagues at Elekta and elsewhere,

I found a bug in  MaxFilter that produces replacement of data chunks with copies of a preceding data chunk in sequence repetitively.

In other words, a chunk of data is repeated several times thereby replacing some of the data that should follow the data chunk that is repeated.

I attach a screenshot showing an example data set (with the problem, above; and fixed, below).

 

The trigger channel and other channels are not repeated, just the MEG channels are repeated. Needless to say, this will result in problems for subsequent ERF analysis.

 

The bug is produced when the hpie and hpig parameters are active because the error and/or goodness-of-fit limits are passed.

This bug happens whether you are just doing head estimation (estimating the quaternion parameters) or actually doing movement compensation.

 

If I set the hpie parameter to a large number and the hpig parameter to zero, the data replacement bug does not happen anymore.

The size of the data chunks seems corresponds to the tSSS time window size specified with -st (i.e., if st is 4 then the chunk of data that is repeated is 4 sec long).

 

The MaxFilter version I was using when I found this was 2.2.15, but I checked with version 2.2.10 and the same (or similar) bug is present related again to hpie and hpig (producing the same exact data replacement with repetitive chunks).

 

Again the solution is to set hpie to a large number (e.g., 1000000) and hpig to 0.

Please make a note, and let others know as this could have been affecting the data sets of many users world-wide who have been performing head estimation or head movement compensation.

 

Best regards,

Rey

--
Rey R. Ramírez, Ph.D.
MEG Brain Imaging Center
Institute for Learning & Brain Sciences
Portage Bay Building
Box 357988
University of Washington
Seattle, WA 98195-7988
e-mail: [log in to unmask]
Tel: (206) 543-6484
Fax: (206) 221-6472
Cell: (619) 709-3590

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