@Eric89GXL yes, but computing the morph map for `accurate=FALSE` should be easy to to do in Python. That's pretty much what my other PR (https://github.com/mne-tools/mne-python/pull/761) does so far. As I understand it, we just have the find the nearest neighbors in the spherical co-registration. Here it will actually be faster as the source space is usually sub-sampled. Let me know if you want me to look into this.