for each axis, it takes the min and the range, and stretch the coordinates so that the range cover the entire head. This is fine when the montage is dense and "uniform", for example this one : but if ...
Add the possibility to specify the value bounds of the colormap range in the mne.Evoked.animate_topomap function. The mne.viz.plot_topomap function implements vmin and vmax for static topomaps but ...