FIX: is_surface() for volume source spaces

[larsoner]

Addresses issue on mne_analysis listserv. Pending tests passing here, I plan on merging to fix the person's issue since this one's a quick fix.

[larsoner]

@agramfort has successfully instilled a fear in me of merging my own PRs, so I'll actually wait for someone to review before merging :)

[agramfort]

LGTM but maybe we should wait for Jon to get his sample vol.stc file. FYI I came up with the -vl.stc myself (2 chars like lh or rh).

[jhouck]

I sent the vol.stc last night -- did that not come through? As you had guessed, it was produced via mne_sensitivity_map with a volume forward model. The attached jpeg is that same stc file with a .jpg extension, which you may or may not be able to download from https://f.cloud.github.com/assets/857583/249528/bd8468b6-8b2f-11e2-8a5f-d33202bc6449.jpg.

The syntax to create the file (in 2.7.4, rev 3394) was:
mne_sentivitity_map --fwd sample_audvis-meg-vol-7-fwd.fif --map 1 --mag --stc ${SUBJECT}_sensitivity_map_mag
where sample_audvis-meg-vol-7-fwd.fif had been created using the tutorial script (run_meg_volume_tutorial.sh).

[larsoner]

@agramfort looks like -vol.stc and -vol.w are defaults for MNE-C. I added the following line to mne-scripts volume tutorial:
https://github.com/mne-tools/mne-scripts/blob/master/sample-data/run_meg_volume_tutorial.sh

mne_sensitivity_map --fwd sample_audvis-meg-vol-7-fwd.fif \
    --map 1 --w sample_audvis-grad-vol-7-fwd-sensmap

This generates the file sample_audvis-grad-vol-7-fwd-sensmap-vol.w. Thus I think it makes sense for us to support both *-vol.* files, as well as volume .w files (neither of which were supported before), since that's what MNE-C produces in this case. Latest commit adds these features, with tests. Let me know what you think.

[larsoner]

@jhouck I was able to produce a similar sensitivity map using the sample dataset. My PR /should/ allow you to use your files. If you'd like to give it a try, you can do the following in your mne-python directory:

$ git remote add Eric89GXL git://github.com/Eric89GXL/mne-python.git
$ git fetch Eric89GXL
$ git checkout -b vol-fix Eric89GXL/vol-fix

And then install as you normally would. If you could take a crack at it to see if it fixes your issues, that would be helpful.

[jhouck]

@Eric89GXL Sure, I'll give it a shot.

[agramfort]

I've updated the build bot with the new test file. Thanks !

[larsoner]

@jhouck now that it has been merged from master, in case you aren't too familiar with Git, you should be able to do something like:

$ git checkout master
$ git fetch upstream # or "git fetch origin" if you have the main repo named that way
$ git pull upstream master

Then install as usual.