Skip to content

plotting: topomap electrode positions change depending on number of channels #5190

@sappelhoff

Description

@sappelhoff

When using topoplot functions in MNE, I run into problems with the electrode positions that are plotted. Namely, when using the code below, the resulting sensor plots should look identical for the electrodes in chan_selection. However, this is not the case:

import mne

chan_selection = [u'FC5', u'FC1', u'C3', u'CP5', u'CP1', u'FC2', u'FC6', u'C4', u'CP2', u'CP6']

montage1020_full = mne.channels.read_montage(kind='standard_1020', ch_names=None)
montage1020_reduced = mne.channels.read_montage(kind='standard_1020', ch_names=chan_selection)

montage1020_full.plot()
montage1020_reduced.plot()

Full

figure_1

Reduced

figure_2


I am aware of a bunch of related issues (e.g., #4880). Issue #3987 seems to be the central issue for this problem ... is anyone working on this currently? It seems like a pretty crucial problem to be solved, given that topoplots are a very common visualization in our domain.

Is this perhaps even affecting the interpolation of voltages across the scalp? Or is this problem merely distorting the "plotted dots" symbolizing the electrodes?

PS: When I use real data and mne.viz.plot_evoked_topomap, I get yet another image for the same electrodes:

screenshot from 2018-05-06 10-50-22

Metadata

Metadata

Assignees

Labels

No labels
No labels

Type

No type

Projects

No projects

Milestone

No milestone

Relationships

None yet

Development

No branches or pull requests

Issue actions