How to get the projected coordinate system of an IGeometry?

SuiHuang

Hi Everybody:

    I made a function to convert X/Y coordinate to Lat/Long coordinates. The interface of the function is
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public static void GetLatLongFromPlannerXY(esriSRProjCSType proj, double x, double y, out double longitude, out double latitude)
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    which takes a predefined projected coordinate system (esriSRProjCSType) as an input.

    Now I want to use ArcObject code to retrieve the projected coordinate system of the point geometry (contains X/Y) to be converted instead of hard-coding it.
1. How can I do that?
2. On another hand, the function I wrote can only take predefined projected coordinate systems. Is there any way to improve it to take any projected coordinated systems?

Below is the function code I wrote, any suggestion will be welcome. Thank you!
*********************************************************
        public static void GetLatLongFromPlannerXY(esriSRProjCSType proj, double x, double y, out double longitude, out double latitude)
        {
            // esriSRProjCSType.esriSRProjCS_NAD1983UTM_15N
            ISpatialReferenceFactory factory = null;
            IProjectedCoordinateSystem projectedGCS = null;
            try
            {
                factory = new SpatialReferenceEnvironmentClass();
                projectedGCS = factory.CreateProjectedCoordinateSystem((int) proj);
                WKSPoint pointToConvert = new WKSPoint {X = x, Y = y};
                projectedGCS.Inverse(1, ref pointToConvert);
                longitude = pointToConvert.X;
                latitude = pointToConvert.Y;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                Utils.ReleaseComObjects(factory, projectedGCS);
            }
        }
**************************************************

AllanMills

The IGeometry interface already has SpatialReference as a property. You should be able to just check that it is of type IProjectedCoordinateSystem and cast it to IProjectedCoordinateSystem if it is.