On Tue, Apr 5, 2016 at 12:02 PM, Karl Taylor <[email protected]> wrote:
> For unstructured grids when some cells are quadralaterals and others are > pentagons, the convention stipulates that bounds should be dimensioned > (n,5) so that the lat and lon locations of all 5 penatagon vertices can be > recorded. My question is what to do about the extra vertex for the > quadralaterals? Should we define a "missing_value" and store it in the > unused vertex location? > Take a look at the UGRID conventions: http://ugrid-conventions.github.io/ugrid-conventions/ In there, the lat-lon are specified in a nodes array, and the cells are specified as indexes into that nodes array. In the case of cells of different order, the "extra" indexes use a missing value, usually -1. That should be defined as the _FillValue. This is under debate right now, but I think that's where it is headed: https://github.com/ugrid-conventions/ugrid-conventions/issues/26 (someone still needs to update the text) BTW, as I read the latest convensions: http://cfconventions.org/cf-conventions/v1.6.0/cf-conventions.html#missing-data you want to use _FillValue if there is only one "Missing" value needed. If so, perhaps we should make this clear in the convention document. > Where does the CF conventions address this issue (i.e. unstructured grids) at all? -CHB -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception [email protected]
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