Project to Lat/Long for Google maps using arcobjects

JohnBerg — Wed, 08 Oct 2014 20:05:02 GMT

I'm trying to take a coordinate and convert it to Lat/Long for google maps but I don't know enough about projections to handle this. I know it should be something like this but not sure what my Geo Types should ge or what the SetFalseOriginAndUnits is used for - can someone point me in the right direction? I'm guessing I don't have the coordinate types correct or I need to project the coordinate somehow.

ISpatialReferenceFactory srFactory = new SpatialReferenceEnvironmentClass();

//GCS to project from

int geoType = (int)esriSRGeoCSType.esriSRGeoCS_NAD1983;

var gcs = srFactory.CreateGeographicCoordinateSystem(geoType);

ISpatialReference sr1 = gcs;

// what should this be???

//sr1.SetFalseOriginAndUnits(-180, -90, 1000000);

//Projected Coordinate System to project into

int geoType2 = (int)esriSRProjCSType.esriSRProjCS_NAD1983N_AmericaLambert;

var pcs = srFactory.CreateProjectedCoordinateSystem(geoType2);

// what should this be???

//pcs.SetFalseOriginAndUnits(0, 0, 1000);

ISpatialReference sr2 = pcs;

//Point to project

var point = new PointClass() as IPoint;

point.PutCoords(2396130.0831298800, 15867438.6259155000);

//Geometry Interface to do actual project

var geometry = point;

geometry.SpatialReference = sr1;

geometry.Project(sr2);

point = geometry;

double latitude;

double longitude;

point.QueryCoords(out latitude, out longitude);

My map layer has this info:

NAD83 UTM, Zone 18 North, US Foot

Authority: Custom

Projection: Transverse_Mercator

false_easting: 1640416.614993545

false_northing: 0.0

central_meridian: -75.0

scale_factor: 0.9996

latitude_of_origin: 0.0

Linear Unit: Foot_US (0.3048006096012192)

Geographic Coordinate System: North_American_Datum_1983

Angular Unit: Degree (0.0174532925199433)

Prime Meridian: Greenwich (0.0)

Datum: D_North_American_1983

Spheroid: Geodetic_Reference_System_of_1980

Semimajor Axis: 6378137.0

Semiminor Axis: 6356752.31414035

Inverse Flattening: 298.2572221009113

Re: Project to Lat/Long for Google maps using arcobjects

RiyasDeen — Thu, 09 Oct 2014 05:10:31 GMT

Hi John,

Your coordinates seem to be projected coordinates but your are assigning a geographic coordinates system in this line geometry.SpatialReference = sr1; You should assign a projected coordinate system for this coordinates (esriSRProjCS_NAD1983UTM_18N in your case)
Geographic coordinates are latitude (valid values -90 to +90) and longitude (valid values are -180 to +180), projected coordiates are generally in linear units meter or miles.
Google maps coordinates are in WGS84 you should project your geometry to esriSRGeoCS_WGS1984

topic Project to Lat/Long for Google maps using arcobjects in ArcObjects SDK Questions

Project to Lat/Long for Google maps using arcobjects

Re: Project to Lat/Long for Google maps using arcobjects