I'm trying to programmatically convert (in C#) feet coordinates to decimal degrees. I'm not so worried about the actual programming (although it would be nice if someone has already created code for this) as I am the math behind the conversion. I've included my coordinate system details below in case they're needed. How can I accomplish this?
Example:
1,985,012.726 449,396.204 Feet --> -97.548833 32.901945 Decimal Degrees
Coordinate System:
NAD_1927_StatePlane_Texas_North_Central_FIPS_4202
WKID: 32038 Authority: EPSG
Projection: Lambert_Conformal_Conic
False_Easting: 2000000.0
False_Northing: 0.0
Central_Meridian: -97.5
Standard_Parallel_1: 32.13333333333333
Standard_Parallel_2: 33.96666666666667
Latitude_Of_Origin: 31.66666666666667
Linear Unit: Foot_US (0.3048006096012192)
Geographic Coordinate System: GCS_North_American_1927
Angular Unit: Degree (0.0174532925199433)
Prime Meridian: Greenwich (0.0)
Datum: D_North_American_1927
Spheroid: Clarke_1866
Semimajor Axis: 6378206.4
Semiminor Axis: 6356583.799998981
Inverse Flattening: 294.9786982
Are you converting a feature class to another feature class or working with individual geometries? For the latter, look at IGeometry2::ProjectEx. What is the output GCS going to be? NAD27, NAD83, etc.? For anything other than NAD27, you'll also need a geographic (datum) transformation like 1241 (NAD_1927_To_NAD_1983_NADCON) or 15851 (NAD_1927_To_WGS_1984_79_CONUS).
Another possibility is to use the Project Tool via Python.
Melita
This is part of a tool that identifies a mouse click location in ArcMap and locates it on online maps. The output coordinates will be used to find locations on Bing and Google Maps.