Dear Karl > Consider a grid consisting of both triangular and rectangular grid > cells with n total grid cells. In this case the cell_bounds for > longitude could be dimensioned (n, 4) because there are a maximum of > 4 cell vertices. > > My question is, for the triangular grid cells do we *require* the > 4th element of the bounds to be set to missing_value? If not, how > does software decide how many vertices each grid cell has?
As Chris says, I don't think we envisaged a mixture of different sorts of polygons. The text at the end of sect 7.1 speaks of "p-sided cells" with "p the number of vertices of the cells". It doesn't suggest that p could be multivalued. We could clarify that with a defect ticket. The proposal by Dave Blodgett and others for simple geometries https://cf-trac.llnl.gov/trac/ticket/164 https://github.com/dblodgett-usgs/cf-conventions/blob/7768e33e7edff459482e8ef8057ea6b8e015c9eb/ch07.adoc does allow for a mixture of different polygons to define the cells of a grid. > Also, in H.2.3 examples H.4 and H.5, missing_value is defined for > the time coordinate, time(time). I don't think coordinates are > allowed to include missing values. Is this a "defect" in our > document? No. It's not normally allowed, but it is permitted for unused elements in discrete sampling geometries. See section 9.6. Best wishes Jonathan _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
