Monday, March 2, 2009

Common CRP Projections

Hi everyone;

Following up on one of my action items from last meeting, I am submitting parameters for the most common projections/coordinate systems used by CRP members.

Johanna canvassed the membership and heard back from Strathmore, Airdrie, Canmore, Cochrane, Calgary, MD Foothills, and MD Rockyview. Without exception, all reporting members principally use 3TM as their main projection. Here are the parameters:

Projection: 3TM (Transverse Mercator)
False Easting: 0
False Northing: 0
Central Meridian: -114.0 (114 deg W longitude)
Scale factor: 0.9999
Latitude of Origin: 0
Linear Unit: Meter (1.000000)

Coordinate System: GCS_WGS_1984
Angular Unit: Degree (0.017453292519943295)
Prime Meridian: Greenwich (0.000000000000000000)
Datum: D_WGS_1984
Spheroid: WGS_1984
Semimajor Axis: 6378137.000000000000000000
Semiminor Axis: 6356752.314245179300000000
Inverse Flattening: 298.257223563000030000

The parameters above represent the most common ones stipulated by respondents to Johanna - they are presented here as a starting point for further discussion if that's what necessary to arrive at a common understanding.

Because it's also commonly used in Alberta, especially with government folks, here are the suggested parameters for Alberta 10TM projection as well:

Projection: Alberta 10TM (Transverse Mercator)
False_Easting: 500000.000000
False_Northing: 0.000000
Central_Meridian: -115.000000
Scale_Factor: 0.999200
Latitude_Of_Origin: 0.000000
Linear Unit: Meter (1.000000)

Geographic Coordinate System: GCS_North_American_1983
Angular Unit: Degree (0.017453292519943299)
Prime Meridian: Greenwich (0.000000000000000000)
Datum: D_North_American_1983
Spheroid: GRS_1980
Semimajor Axis: 6378137.000000000000000000
Semiminor Axis: 6356752.314140356100000000
Inverse Flattening: 298.257222101000020000

Thanks to Johanna and Ken for compiling this information and passing it along. Hope to see you all tomorrow,


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