[CF-metadata] Polar stereographic projection question

Karl Taylor taylor13 at llnl.gov
Thu Mar 6 10:14:52 MST 2008


Dear all,

We received an email suggesting that a parameter was missing from the CF 
polar stereographic projection documentation.  Can anyone clear this up?

thanks,
Karl

Sue Dettling wrote:
 >
 > I am wondering if you are missing an arguement from the Polar 
stereographic projection documentaion
 > 
(http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.0/apf.html#id2976188)
 >
 > You list the following parameters for the projection:
 > 1) straight_vertical_longitude_from_pole
 > 2) latitude_of_projection_origin - Either +90. or -90.
 > 3) Either standard_parallel or scale_factor_at_projection_origin
 > 4) false_easting
 > 5) false northing
 >
 >
 > The  proj4 reference 
http://www.remotesensing.org/geotiff/proj_list/polar_stereographic.html 
lists the following:
 >
 > +lat_ts=Latitude at natural origin
 > +lat_0=90
 > +lon_0=Longitude at natural origin
 > +k_0=Scale factor at natural origin (normally 1.0)
 > +x_0=False Easting
 > +y_0=False Northing
 >
 >
 > In reading both pages it seems the corresponence of args is:
 > +lat_ts ==  ???
 > +lat_0 ==   (2) latitude_of_projection_origin
 > +lon_0 ==   (1) straight_vertical_longitude_from_pole
 > +k_0 ==     (3) scale_factor_at_projection_origin
 > +x_0=False Easting ==  (4) false_easting
 > +y_0=False Northing == (5) false northing
 >
 > Is this an error in the documentation that there doesnt seem to be a 
  map parameter for lat_ts?
 >
 > Thanks, your response is greatly appreciated,
 >
 > Sue



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