Here is an example of a projection (modis sinusoidal) that is not
supported by CF:
PROJCS["unnamed",
GEOGCS["Unknown datum based upon the custom spheroid",
DATUM["Not_specified_based_on_custom_spheroid",
SPHEROID["Custom spheroid",6371007.181,0]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433]],
PROJECTION["Sinusoidal"],
PARAMETER["longitude_of_center",0],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]]]
Using GDAL's netcdf driver (dev version) to convert a gtiff file with
this projection to netcdf, the associated CF grid_mapping is
char sinusoidal ;
sinusoidal:grid_mapping_name = "sinusoidal" ;
sinusoidal:longitude_of_prime_meridian = 0. ;
sinusoidal:semi_major_axis = 6371007.181 ;
sinusoidal:inverse_flattening = 0. ;
sinusoidal:false_easting = 0. ;
sinusoidal:false_northing = 0. ;
sinusoidal:longitude_of_central_meridian = 0. ;
sinusoidal:spatial_ref = "PROJCS[\"unnamed\",GEOGCS[\"Unknown datum
based upon the custom
spheroid\",DATUM[\"Not_specified_based_on_custom_spheroid\",SPHEROID[\"Custom
spheroid\",6371007.181,0]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433]],PROJECTION[\"Sinusoidal\"],PARAMETER[\"longitude_of_center\",0],PARAMETER[\"false_easting\",0],PARAMETER[\"false_northing\",0],UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]]]"
;
sinusoidal:GeoTransform = "-7783653.63766700029 463.312716527500015
0 1111950.51966700004 0 -463.312716527500015 " ;
The last 2 attributes (spatial_ref and GeoTransform) are used by
GDAL's netcdf driver because the CF standard does not support it
(yet).
As you can see, the only thing that is not CF is the sinusoidal
grid_mapping_name
On Mon, Nov 21, 2011 at 11:37 AM, Jonathan Gregory
<j.m.gregory at reading.ac.uk> wrote:
> Dear all
>
> Several people contributed to an email thread in October about OGC CRS WKT.
> It would help the discussion about how to include WKT, or the ideas it
> embodies, in CF if we had some more concrete examples of coordinate systems
> that people would like to use in CF but can't currently be represented in CF,
> and how they are described in WKT. If you can post any to this email thread,
> that would be much appreciated.
>
> Also, anyone is welcome to contribute to trac ticket 69, as below, where we are
> discussing this.
> https://cf-pcmdi.llnl.gov/trac/ticket/69
> To contribute, you need a CF trac account. Please email
> webmaster at pcmdi.llnl.gov
> to request one if you don't have one.
>
> Best wishes and thanks
>
> Jonathan
>
>
> ----- Forwarded message from Jonathan Gregory <j.m.gregory at reading.ac.uk> -----
>
>> Date: Wed, 9 Nov 2011 09:56:01 +0000
>> From: Jonathan Gregory <j.m.gregory at reading.ac.uk>
>> To: cf-metadata at cgd.ucar.edu
>> Subject: Fwd: Re: [CF-metadata] Question on WKT representation of CRS
>>
>> Dear all
>>
>> It would be very helpful if those who are familiar with OGC CRS WKT - several
>> people contributed to this email thread in October - could contribute to the
>> discussion in trac ticket 69. In this ticket, Phil Bentley has proposed a new
>> attribute to allow WKT to be recorded in CF metadata. I am grateful to Phil
>> for making the proposal, but I am concerned about our adopting this proposal
>> because of possible inconsistency with other CF metadata. I have described
>> some specific concerns in the ticket, and asked what specific requirements
>> there are i.e. more use cases, because I think it is necessary to understand
>> the implications of what we put in the CF standard. Unfortunately I don't know
>> much about how the parts of the coordinate reference system are defined, but
>> other people who read this email list must do, I am sure! If anyone can add
>> further information and viewpoints to the discussion, it would help.
>>
>> Best wishes and thanks
>>
>> Jonathan
>
> ----- End forwarded message -----
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> CF-metadata at cgd.ucar.edu
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>
Received on Mon Nov 21 2011 - 13:24:49 GMT
