moonwalk
Posts: 1
Joined: Fri May 14, 2010 4:07 am

Converting WGS84 to NAD83 MD state plane

Fri May 14, 2010 4:29 am

I have a requirement to convert WGS84 coordinates from a bing map to NAD83 MD state plane in feet. I am using GPSTools to do the conversion. Here is my code:

GpsToolsNET.Position ctGPSPos = new GpsToolsNET.Position();

ulLon = "-76.6296";
ulLat = "39.30844";


//Current UL Coordiantes in WGS84
ctGPSPos.Longitude = double.Parse(ulLon);
ctGPSPos.Latitude = double.Parse(ulLat);

//convert to NAD83
ctGPSPos.Datum = GpsToolsNET.Datum.NAD_83;//NAD_83; //19
ctGPSPos.Grid = GpsToolsNET.Grid.UTM_NAD_83;

//Assign the NAD83 coords (gives the coords in meters)
ulLon = ctGPSPos.Easting.ToString();
ulLat = ctGPSPos.Northing.ToString();

//Convert meters NAD83 to Feeet NAD83
double ulnorthing = double.Parse(ulLat) * FEET_MULTIPLIER;//latitude, Y coord
double uleasting = double.Parse(ulLon) * FEET_MULTIPLIER; //longitude, X Coord

I tried it with a test coordinates from a bing map for which I have corresponding coordiantes in feet in our DB. The values in feet for this location in the DB are 1417216.588(longitude) and 598399.591(lat). The conversion code is returning 14279105.465705095(lat) and 1179465.2036274525(longitude).

So, what am I doing wrong here?

Thanks.

User avatar
johan
GpsGate
Posts: 14887
Joined: Wed Aug 04, 2004 10:40 pm
Location: Sweden
Contact: Website

RE: Converting WGS84 to NAD83 MD state plane

Mon May 17, 2010 5:24 pm

If you want to convert to NAD84 State Plane, you need to know which state, and which zone in that state to convert to. More info here:
http://franson.com/gpstools/reference_manual.asp?comp=tools&class=Position&item=Zone&platform=net

The name of the grid is GpsToolsNET.Grid.SPCS_83

You got a suitable sample for California Zone1 here:
http://franson.com/gpstools/reference_manual.asp?class=Position&item=Grid&platform=net

Regards,
Johan

Franson Support

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