I believe that most of Jon's comments regarding the overlap between gridspec and ugrid were related to the topic of mosaics. This is a very important aspect in gridspec and since we will need to store mosaics of unstructured meshes as well I had included some initial ideas on this topic in the first ugrid docs. We didn't include this part in the official ugrid-0.9 version because of the remaining discussion and since we didn't need it yet at the time. The sgrid proposal (a staggered structure mesh convention alike ugrid) is a more direct alternative to gridspec's supergrid concept.
Good night from Europe,
Bert
Chris Barker <chris.barker at noaa.gov>schreef:
On Thu, Dec 10, 2015 at 8:19 AM, Jonathan Gregory <j.m.gregory at reading.ac.uk<mailto:j.m.gregory at reading.ac.uk>> wrote:
After that proposal was agreed, we had some further discussions concerning the
relationship of gridspec and ugrid and how they could be made more similar.
I remember that conversation, though I never took the time to look at gridspec.
For reference, here is the current UGRID spec:
https://github.com/ugrid-conventions/ugrid-conventions/blob/master/ugrid-conventions.md
I just looked at:
http://www.gfdl.noaa.gov/~vb/gridstd/gridstdse3.html#x5-240003.4
And my first impression is that while it is handling the same information as UGRID, it's pretty different, at least with respect to variable names. My impression is thus:
gridspec was developed to support a certain set of (structured) grids. The unstructured bit was then added to well-match the model and conventions that had been established.
UGRID, n the other other hand was built from scratch, based on CF and the vocabulary and conventions that unstructured grid (oceanographic) modelers use. So it's a more wordy, but actually matched pretty well with what FVCOM, ADCIRC, SELFE, etc already put out.
So: I don't think that we in the UGRID community are going to want to turn what we'be got on end to match gridspec. I suspect the gridspec community is in the same position. Thugh: how much is gridspec used for unstructured grids? If not much then maybe just drop that support, and use UGRID.
HOWEVER: I haven't looked closely enough -- maybe the differences really are just vocabulary -- so maybe we could unify them if we allow multiple names for the same thing. i.e, in a triangular mesh grid, you specify either:
var_name:cf_role = "face_node_connectivity" ;
or
var_name:standard_name = "neighbor_cell_index"
though, honestly, gridspec doesn't look very CF-y to me anyway :-)
-CHB
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
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