Dear all, I think this is the sentence that we need to work on?
> A grid mapping variable is required if, in addition, it is desired to > describe the mapping between the given coordinate variables and the true > latitude and longitude coordinates, or to describe the figure of the Earth > used to define the latitude and longitude coordinates, or to describe another > coordinate reference system definition used by some coordinates or auxiliary > coordinates. A change to: A grid mapping variable is required if __the given coordinate variables are relative to a planetary latitude longitude datum,__ or to describe the figure of the Earth used to define the latitude and longitude coordinates, or to describe another coordinate reference system definition used by some coordinates or auxiliary coordinates. `planetary latitude longitude datum` is intended to take care of @hrajagers use case of x/y coordinates that are not relative to the earth (or mars!). This brings up a long standing beef I have with this. I would also like to suggest this change: > or to describe the figure of the Earth used to define the latitude and > longitude coordinates or to describe the __latitude and longitude datum in the case that assumption of any arbitrary datum could lead to misinterpretation of the data__, And, to be honest, I don't know what the third clause of this sentence means. Could it be dropped? Best, - Dave p.s. @ajelenak-thg and Randy, I actually think the whole point of this is so data providers DON'T have to provide coordinate data for every pixel. This will allow us to publish grid mappings that express the projected coordinate systems our data are represented in. Further, I kind of take issue with this being posed as a data provider/data consumer dichotomy. IMHO, data with 2/d lat/lon arrays that expand to many gigabytes when put in memory become literally unusable. e.g. It doesn't matter if you are a data provider or consumer if the 2/d lat lon is too big to work with the requirement can't be followed anyways. -- You are receiving this because you commented. Reply to this email directly or view it on GitHub: https://github.com/cf-convention/cf-conventions/pull/133#issuecomment-407857186
