coordinate convertor on stereographic projections

damianbrody

Hi Mike,

I understand the Polar Stereographic Projection and the Stereographic Projection should give the same answer if we specify the right parameters. More concretely, the Universal Polar Stereographic projection (UPS) can be specified whether we use the scale factor (0.994) or the latitude of true scale (81.11451786859362545 deg).

So, in this case Global Mapper generates different coordinates when we specify 81.11451786859362545 deg for the Stereographic projection and 0.994 for the Polar Stereographic Projection.

Notice also that the Oblique Stereographic Projection produce the right answers when using the above parameters.

Am I missing something?

Thanks

Damian

global_mapper

Damian,

I don't believe it is the case that Stereographic and Polar Stereographic should generate the same values for the same parameters, otherwise why would you need both projections? The Polar Stereographic projections are centered on either pole, I think to get the same thing in normal Stereographic you could have to set the Central Latitude to +90 or -90 and then the scale factor parameter is what is used to give you what the 'True Scale Latitude' represents for Polar Stereographic. Using 81.114... for the Central Latitude for Stereographic would center the projection on that latitude and the given longitude, which is not the same as Polar Stereographic centered on the pole.

Let me know if I can be of further assistance.

Thanks,

Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com