[Qgis-user] A suggestion to define a proj4 string

[Tudorache, Marian]

Hi,

I got some vectorial projected data. The data reference is stereographic where lat_0=53.354166  and lon_0=-114.8525
The data spec also gave me this:
Major_Axis_Csp= 6378137
Minor_Axis_Csp= 6356752.31414
Gnomonic_Scale_Factor_Csp= 0.9984
Stereographic_Scale_Factor_Csp= 0.9996
Utm_Scale_Factor_Csp= 0.9996
Ups_Scale_Factor_Csp= 0.994
Rdps_Eccentricity_Squared_Csp= 0.00672267
False Northing= 0
False Easting = 0

So I tried to define a proj4 string to be used in QGIS.
This is what I found so far:
Major_Axis_Csp = +a
Minor_Axis_Csp = +b
False Northing   = +y_0
False Easting   = +x_0
I figured out based on major and minor axis the ellps is using GRS 1980 model
What I cannot figured out is how to use the four scale factors in proj4. My fist assumption is to use Stereographic_Scale_Factor_Csp value for k_0 scaling factor.
Did someone encountered such projection specifications?
This is the proj4 string that I defined
+proj=sterea +lat_0=53.354166 +lon_0=-114.8525 +k_0=0.9996 +x_0=0.0 +y_0=0.0 +a=6378137 +b=6356752.31414 +ellps=GRS80 +units=m +no_defs
Do you think is correct?

Thank you,
Marian


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