Hi John,
I'm not completely sure if this is what you want, but I can provide an
example:
http://thredds.met.no/thredds/catalog/metno/proff4km/default/catalog.html
grid_mapping_name: rotated_latitude_longitude
grid_north_pole_longitude: 156.0
grid_north_pole_latitude: 23.5
This refers to an oblique transformation of the latitude longitude
values. The corresponding proj.4 string is:
+proj=ob_tran +o_proj=longlat +lon_0=-24 +o_lat_p=23.5
Conversion between CF and proj.4 is:
grid_north_pole_longitude = normalize180(180 + lon_0)
grid_north_pole_latitude = o_lat_p
where normalize180 makes sure that grid_north_pole_longitude stays
within [-180,180].
We are using private EPSG-codes (e.g. we haven't uploaded them to
http://spatialreference.org), so nothing to use as reference here. And I
have no example with north_pole_grid_longitude, and I don't know if it
is +o_lon_b or similar?
As a reference, I used
http://download.osgeo.org/proj/proj.4.3.I2.pdf
chapter 4: Creating oblique projections
Best regards,
Heiko
On 2012-04-19 18:49, John Caron wrote:
> This grid mapping has no reference implementation or any other
> documentation. I think we have to have something. Can anyone supply?
>
>
> Rotated pole
>
> |grid_mapping_name| = rotated_latitude_longitude
>
>
> /Map parameters:/
>
> *
>
> |grid_north_pole_latitude|
>
> *
>
> |grid_north_pole_longitude|
>
> *
>
> |north_pole_grid_longitude|- This parameter is option (default
> is 0).
>
> /Map coordinates:/
>
> The rotated latitude and longitude coordinates are identified by
> the|standard_name|attribute
> values|grid_latitude|and|grid_longitude|respectively.
>
> /Notes:/
>
>
Received on Fri Apr 20 2012 - 07:19:46 BST
