Consider z axis about stac-spec

[m-mohr]

I think that could be an important one if we want to cater for all domains especially such as meteorology.

For the datasets we specified a dimensions extension. I am not sure whether that really fulfills all needs yet. What about items? It seems like the new API spec supports the z-axis already, at least I found references for that during my review of #167.

I already heard voices within openEO that were not very comfortable with GeoJSON as it doesn't allow the z-axis to be specified.

Do we have any expert that we could consult regarding this?

[matthewhanson]

GeoJSON does allow for an optional 3rd dimension to allow for altitude @m-mohr and this will be needed for a point cloud extension cc @hobu

[m-mohr]

Oh, interesting, thanks for pointing that out. Never saw that in the wild yet, but you are certainly right I just looked it up directly in the spec/RFC.

[m-mohr]

The z-axis has been added to the dataset spec with #239. We should consider adding similar things to the item.

[matthewhanson]

There is no reason to not allow a 3rd dimension in the Item, and I think we do because it's a GeoJSON geometry which allows for it.
However, our description of Geometry and Bounding Box should be updated to say not just lat/lon, but lat/lon/

I'm moving this to 0.8.0 as it's just a clarification.

[m-mohr]

Agreed, we should also check the descriptions for spatial collection extents.