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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi, > - Wavelength: we find it necessary to add the minimum and maximum wavelength > (spectral range) to the metadata. We think it is not enough just to specify > one > wavelength for a band. > >> i think this is the same as a coordinate bounds, see section 7.1: > >> http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#cell-boundaries That sounds correct. I will see if I can use this. > - Geolocalization: we have quite a lot of data that is easily represented on a > grid, but the CF-convention requires the grid of lons and lats to be > calculated. > This is of course highly inconvenient for fixed grids (from a data storage and > transfer perspective). We suggest adding a proj-string (proj.4 string > definition) and an area-extent option in the convention for grids. To us, it > makes a lot more sense than maintaining a list of accepted pre-defined grids > in > the convention. > >> 1) there are a set of accepted projections in appendix F : > >> http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#appendix-grid-mappings > >> does your data fall into one of those. if not, can you describe? > >> proj-4 strings are an alternate representation, which have been >> discussed in the past on the CF list. you can include them, of course, >> but they are not currently part of the CF spec. As of now, we are using grids in "geos" projection, so vertical perspective will fit very well. One thing though: is there any specific attribute for the area extent (lower left and upper right projection coordinates) ? I see projection_[x,y]_coordinate, but that has to be a vector of the size of the data... Including the proj4 string was just a suggestion, since I did not know there was the grid mappings in the conventions. As a side note, in the link you gave, the cf documentation states that proj.4 only supports "geos", which is vertical perspective over the equator. This is not true, since there is the "near-sided perspective" projection (+proj=nsper) which is like geos over any point of the globe. I am not able to create an account on the cf-metadata trac, so do you know who I should contact ? >> 2) the question of having to include calculated lat/lons has also been >> discussed many times. I have advocated making these optional, but my >> opinion has not prevailed (yet). The Netcdf-Java software does not >> require them as long as a projection (grid_mapping) is specified. Other >> software may not know how to deal with the projections, so thats the >> argument for including. I agree with you that including lat/lon is useless when providing a projection. A software not knowing how to deal with projections would probably not do anything usefull with lon/lats anyway... Best regards, Martin -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJMdMb+AAoJEBdvyODiyJI4TwoIAMh0TuThZDbuZ++Y3THaoFcb nV5gClvB2bESSB8GMz+G31Vyv1JhM9c9S1jaX71AfCkIoWIFuhE9P78gVWumyjfK pPpicEPcF9h3UBg4/bIiAaM7my+SJTH954yvxgI/hELVIbhOYdapsubWbTnRseXr SCJMpA5y7QcbgdQSbYg7zy+44HndiUnNUd4UWO7nZx4xZ6xCoi76bxXBn80EmCCa qs8sqh+OwY993Qw6QbKlPxratIUth0LmRGrF8rZKc3fV6LfOFhGEYTwNmr5VDjYg TKzVkuCaNhlZmxZijK+ncGGtaJOijrdZjgD9rkBesOnqnYVNhfWQeUFKq+H0rUg= =6Bk5 -----END PGP SIGNATURE-----
begin:vcard fn:Martin Raspaud n:Raspaud;Martin org:SMHI adr;quoted-printable:;;;Norrk=C3=B6ping;;60176;Sweden email;internet:martin.raspaud@xxxxxxx tel;work:+46 (0)11 495 8261 tel;cell:+46 (0)11 495 8261 x-mozilla-html:FALSE version:2.1 end:vcard
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