Handling surfaces (meshes) in NIDM-Results

[cmaumet]

We intentionally used a broad definition for nidm:Map: "An ordered set of values corresponding to the discrete sampling of some process (e.g. brain MRI data measured on a regular 3D lattice; or brain cortical surface data measured irregularly over the cortex)" that encompasses both volumetric and surface data.

So far the NIDM-Results specification has mainly focused on volumetric data. In a future release, we should check the consistency of the model with respect to the representation of surface data (and add tests).

I would be happy to contribute! I think @gllmflndn was also interested in this in the context of the analysis of MEG data.

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This issue is open following @bthirion's comment on the NIDM-Results minimal JSON API.