[FieldTrip] sourceplot

[qi li]

Hi,

I am having trouble to call the ft_sourceplot after ft_sourceanalysis.

After sourceanalysis I have a source struct

ans =

       time: [1x399 double]
        pos: [8196x3 double]
     inside: [1x8196 double]
    outside: [1x0 double]
     method: 'average'
        avg: [1x1 struct]
        cfg: [1x1 struct]
       unit: 'cm'
Avg field has the following  structure

ans =

    mom: {1x8196 cell}
    pow: [8196x399 double]

I want to plot the pow in the brian, so I use
cfg = [];
cfg.method        = 'ortho';
cfg.funparameter  = 'avg.pow';
cfg.maskparameter = cfg.funparameter;
cfg.funcolorlim   = [0.0 1.2];
cfg.opacitylim    = [0.0 1.2];
cfg.opacitymap    = 'rampup';
figure
ft_sourceplot(cfg, source);

but the message says 'Error using ft_checkdata (line 307)
This function requires volume data as input.

Error in ft_volumedownsample (line 58)
source = ft_checkdata(source, 'datatype', 'volume', 'feedback', 'no');

Error in ft_sourceplot (line 290)
data = ft_volumedownsample(tmpcfg, data);'

What does volume data point to? Thanks!