[FieldTrip] Fwd: ft_sourcegrandaverage and ft_sourceplot usage

[gj]

Hi,

I had computed source reconstruction in the frequency domain of my EEG
data -- followed by
   * ft_sourcedescriptives with cfg.projectmom="yes"
   * set the resulting
	source_proj.dim = grid.dim
	source_proj.pos = grid.pos
   * ft_sourceinterpolate onto an MNI template brain

but for some conditions of some subjects, this resulting localizations
were predominantly in the center of the head. So, I was thinking of
calculating the grand average of the source (though is this kosher when
I have obvious individual source modeling problems?):

-----
cfg.parameter 		= 'avg.pow';
cfg.keepindividual 	= 'yes';
cfg.outputfile 		= 'srcGrandAvg';
srcGrandAvg 		= ft_sourcegrandaverage(cfg, source_interp{:}); %
source_interp = output of ft_sourceinterpolate
-----

I'm not sure if my approach is correct because this results in a HUGE 
(several hundred MBs) srcGrandAvg matrix per condition that takes 
forever to write to disk. Moreover I cannot seem to plot it with 
ft_sourceplot (doesn't plot the source averaging results):

-----
cfg = [];
cfg.funparameter = 'pow';
cfg.method='ortho';
srcGrandAvg.anatomy = mri.anatomy; % from load('standard_mri.mat');
figure
ft_sourceplot(cfg,srcGrandAvg);
-----

ft_sourceplot gives me the messages:

-----
the input is source data with 7109137 brainordinates on a [181 217 181] grid
scaling anatomy to [0 1]
not plotting functional data
not applying a mask on the functional data
not using an atlas
not using a region-of-interest
-----


My output from ft_sourcegrandaverage looks like this:

-----
         srcGrandAvg =

          pow: [19x7109137 double]
     coordsys: 'spm'
          dim: [181 217 181]
         freq: 12
       inside: [7109137x1 logical]
          pos: [7109137x3 double]
         unit: 'mm'
          cfg: [1x1 struct]
      anatomy: [1x1 struct]
-----

Thanks in advance for any help or advice!!!
Gina