[GRASS-user] Defining a State Plane Coordinate Location
Glynn Clements
glynn at gclements.plus.com
Sun Jul 24 10:43:26 EDT 2011
Rich Shepard wrote:
> Since SPCS is a derivative of the Transverse Mercator projection, the site
> I found (which provides the data for free while selling projection
> conversion software for Microsoft systems) tells me:
>
> False northing: 8000000
> False easting: 200000
> Origin Latitude: 43.75
> Origin Longitude: -115.583333333333
> Parallel North: 0
> Parallel South: 0
> Scale Factor: 0.9999
>
> It also has 0 as the parameters for NAD83 (apparently already adjusted)
> and those for GRS89. I intend to use the above to define the location unless
> I'm way off.
PROJ's EPSG file says:
# NAD83(HARN) / Nevada East (ft US)
<3429>
+proj=tmerc
+lat_0=34.75
+lon_0=-115.5833333333333
+k=0.9999
+x_0=200000.00001016
+y_0=8000000.000010163
+ellps=GRS80
+units=us-ft
Which is identical except for lat_0 (34.75 vs 43.75), which might be a
transcription error.
According to:
http://www.ngs.noaa.gov/PUBS_LIB/ManualNOSNGS5.pdf
"NOAA Manual NOS NGS 5 - State Plane Coordinate System of 1983"
34.75° (34°45') is correct for SPCS 2701 (Nevada East); page 68 (PDF
page 78) says:
Grid Origin
Central Meridian Longitude Easting
State/Zone/Code Projection and Scale Factor Latitude Northing
Nevada NV
East E 2701 T.M. 115 35 115 35 20,000.
1:10,000 34 45 8,000,000.
--
Glynn Clements <glynn at gclements.plus.com>
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