[Proj] WGS84 to Minnesota State Plane South

[Anthony Dunk]

Using my own coordinate conversion program (which calls the PROJ dll),
I got the following results when converting your test point from WGS84
lat/lon to US State Plane (NAD83, US survey feet) Minesota 2203, South
Zone: Easting=2821052.4, Northing=1017159.1. These results are quite
close to the reference point you gave.

I couldn't see any differences in the parameters I was passing to PROJ
compared to yours.

The PROJ string I'm using for this US state plane coordinate system is:

+proj=lcc +lat_1=48.7833333333 +lat_2=45.2166666667 +lat_0=43
+lon_0=-94 +x_0=800000 +y_0=100000 +a=6378137 +rf=298.257222101
+to_meter=0.3048006

Anthony.

--- Arno Gerretsen <arno at agerrius.nl> wrote:

> Hi,
> 
> I am trying to convert some data for a friend from WGS84 lat/lon to 
> Minnesota State Plane South. I use the proj4 library for that, but
> the 
> results do not match with some of the control point data he gave me.
> So 
> I am wondering if I maybe did something wrong in my code. Here is the
> 
> code I used:
> 
> PJ *prjState = pj_init_plus("+proj=lcc +lat_0=43 +lon_0=-94 
> +lat_1=45.21666666666666666666666666666666666 
> +lat_2=43.783333333333333333333333 +x_0=800000 +y_0=100000
> +ellps=GRS80 
> +datum=NAD83 +units=ft +no_defs");
> PJ *prjWGS = pj_init_plus("+proj=latlong +ellps=WGS84 +datum=WGS84");
> 
> double x[1], y[1], z[1];
> int err;
> 
> x[0] = -93.242251388888888888888888888889 * DEG_TO_RAD;
> y[0] = 44.887752777777777777777777777778 * DEG_TO_RAD;
> z[0] = 0.0;
> 
> err = pj_transform(prjWGS, prjState, 1, 1, x, y, z);
> 
> With this code and for the lat/lon values listed in the code, I get
> the 
> following State Plane coordinates returned: 2821057.917382
> 1017161.112401
> 
> While the reference data says it should be: 2821052.29398607, 
> 1017159.04559559
> 
> As you can see the difference is a few feet. Can anybody tell me if I
> 
> have done something wrong in my code, or should I doubt the quality
> of 
> the reference data :)?
> 
> Thanks,
> 
> Arno
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> 


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