Hello,

I have several questions about the appropriate usage of maxfilter.  I 
may have mis-understood some of the calculations maxfilter is 
performing, so please correct me, where I'm wrong.

Several people at the CBU have been told that when they run into the error:

ERROR: sphere fitted to isotrak extends outside of the sensors! (r0 = (12
12 45) mm, rad = 10 cm)
Opened FIFF file lista4first_raw.fif (1350 data buffers).
Output file lista4first_sss_raw.fif was not written (exit value = 3)!

They should use -origin 0 0 45 -frame head.  However, this instruction 
seems very dangerous without at least some preliminary tests e.g. How 
much are we changing the position of the sphere from what was calculated 
with the Digitized points?  Given the radius of the sphere being 
calculated, will this position change include all of the head?  Why 
can't we specify both the origin and the radius?  We should be able to 
visualize these spheres using mri_lab (or some other program ideally one 
in which we can visualize the device, the mri, and the spheres).  We can 
certainly currently visualize created spheres in mri_lab.

Is there any limit to the number of times we can run maxfilter on a 
dataset e.g. (can we run it once with -autobad, another time with 
-movecomp, another time with -trans) If so how do we apply -nosss e.g 
-autobad with -nosss, -movecomp without -nosss, and -trans without -nosss.

Also:

Can we -trans evoked data sets (Has this been thoroughly tested and 
confirmed to work: if so how)?

Can you do SSS without -trans and then -trans the SSS data set?

It seems like maxfilter is actually utilizing several different 
functions/programs, it would be very beneficial if each function/program 
was a seperate /neuro/bin/util/, so we could avoid all of these 
interaction issues.  Towards that end can you give us a comprehensive 
list of the options, which correspond to different tools?

I would also like to get some critical log information when running 
maxfilter e.g. what spheres were used their radii and origins;  when 
maxfilter has interpolated a channel I would like a measure of how 
faithfully the channel has been represented (e.g. deviation from what 
would have happened if there was channel data?  Different collections of 
channels marked bad in different locations will give different quality 
representation of the channel. e.g. in a worst case scenario three 
complete (x gradiometer, y gradiometer, and magnetometer) chips next to 
one another would be marked bad).  I may be misunderstanding the way 
this works, but the representation should not be as faithful.

Thank You,
Dan