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On 11/22/2011 3:39 PM, Raspaud Martin wrote:
Hi John,This looks familiar indeed... The document cited there is the CGMS03, which describes the geos projection. However, I am not sure what scale_x and y are ?
they are from section 4.4.4 of: http://www.eumetsat.int/idcplg?IdcService=GET_FILE&dDocName=PDF_CGMS_03&RevisionSelectionMethod=LatestReleasedsomething to do with the geometry of the specific instrument, needed to actually convert to km on the earth.
perhaps some expert can help us on this?
Should we merge the two descriptions somehow for the proposal ?
yes, if they are really the same. Its a port of this software: * Port Eumetsat MSG_navigation.c to java* from http://www.eumetsat.int/idcplg?IdcService=GET_FILE&dDocName=zip_tools_msg_nav_c&RevisionSelectionMethod=LatestReleased
Best regards, Martin ----- Reply message ----- Från: "John Caron" <caron@xxxxxxxxxxxxxxxx> Till: "cf-satellite@xxxxxxxxxxxxxxxx" <cf-satellite@xxxxxxxxxxxxxxxx>Rubrik: [cf-satellite] Making a proposal for the addition of the geos projectionDatum: tis, nov 22, 2011 18:01 Hi Martin:Im wondering what relationship this projection has (if any) with the meteosat projection:http://www.unidata.ucar.edu/software/netcdf-java/reference/StandardCoordinateTransforms.html#MSG John On 11/22/2011 5:28 AM, Martin Raspaud wrote:-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi all, There seems to be a need from the weather satellite folk to add the "geos" projection to the list of projections in the CF metadata. "geos" stands for geostationary. The projection is described in detail in the "CGMS 03, LRIT/HRIT Global specification" document. (see here also:http://remotesensing.org/geotiff/proj_list/geos.html ) My question is thus: how do we make a proposal for the addition of the projection ? On a side note, it looks like "Vertical perspective" and "geos" are mixed up in the current version of the conventions (the link to "geos" is provided under "Vertical perspective"). The difference is that the geos projection is related to scanning angles of the satellite, so that the projection is done on a piece of a sphere, while the vertical perspective is a kind of orthographic projection. Here comes a possible text for this projection: Geostationary - ------------- grid_mapping_name = geos Map parameters: latitude_of_projection_origin longitude_of_projection_origin perspective_point_height false_easting false_northing Map coordinates: The x (abscissa) and y (ordinate) rectangular coordinates are identified by the standard_name attribute value projection_x_coordinate and projection_y_coordinate respectively. Notes: Notes on using the PROJ.4 software packages for computing the mapping may be found at http://www.remotesensing.org/geotiff/proj_list/geos.html . These notes assume the point of observation is directly over the equator. ============================== Thanks a lot ! Best regards, Martin -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (GNU/Linux) Comment: Using GnuPG with Red Hat -http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJOy5VwAAoJEBdvyODiyJI4uCYIAIBdFb7vgvg6ro4k/uWDm1VZ JehlzqZl+CVBN0wFlVABgAe3UHKOS3Q1IEr9+JkcvFzxsMFSHfaCmj02IeqtV5cQ yTbI+3KgHnKC9udXnbl84aMOmUZHvalBkM0+2Rc49pmNvd2xqC0FZDqclnVqM0Gf 8Rrq66txOh2tBK1rJO94EVq4p8JtbC78Dd9ayiHdUZwKz/DlxePR6YgYqcMyci9M MtXV3kdvsgYzl8epzyrEoCyuSMdabOzmgUnztWadDUMidQtp6ygcHXcbLmSq8KMS SGEmgyJIbCt4Krm+aKNU0bKpbsPrOmb6ZbnHCZb4DvVtxIcu0PzaV73366Maheg= =KY33 -----END PGP SIGNATURE----- _______________________________________________ cf-satellite mailing list cf-satellite@xxxxxxxxxxxxxxxx For list information or to unsubscribe, visit:http://www.unidata.ucar.edu/mailing_lists/
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