topic Re: Convert ISpatialReference to WKT in ArcObjects SDK Questions

Convert ISpatialReference to WKT

AbelPerez — Thu, 16 Dec 2021 20:11:49 GMT

ArcMap 10.8.1 using .NET ArcObjects

I have a geometry with a spatial reference. How do I get its projection WKT? I've been looking for hours and can't seem to find a simple way to do this.

Dim pGeom As IGeometry = CreateGeometry()

Dim wkt as String = pGeom.SpatialReference.ToWKT '<=== What API do I use for this conversion?

The output should be something like:

PROJCS["World_Azimuthal_Equidistant",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Azimuthal_Equidistant"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-86.02400831252139],PARAMETER["Latitude_Of_Origin",41.70912056625856],UNIT["Meter",1.0]]

Re: Convert ISpatialReference to WKT

GKmieliauskas — Fri, 17 Dec 2021 09:02:42 GMT

Hi,

You can serialize ISpatialReference object to xml ant then read wkt from it. Code for serialization:

private static string GetSpatialReferenceAsXmlString(ISpatialReference spatialReference) { if (spatialReference == null) throw new ArgumentNullException("spatialReference"); var xmlStream = new XMLStreamClass(); var xmlWriter = new XMLWriterClass(); var xmlSerializer = new XMLSerializerClass(); xmlWriter.WriteTo(xmlStream); xmlSerializer.WriteObject(xmlWriter, null, null, string.Empty, string.Empty, spatialReference); return xmlStream.SaveToString(); }

You will get xml like this:

<ProjectedCoordinateSystem xsi:type='typens:ProjectedCoordinateSystem' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:typens='http://www.esri.com/schemas/ArcGIS/10.8'> <WKT>PROJCS["LKS_1994_Transverse_Mercator",GEOGCS["GCS_LKS_1994",DATUM["D_Lithuania_1994",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",24.0],PARAMETER["Scale_Factor",0.9998],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]</WKT> <XOrigin>-22523120044.116333</XOrigin> <YOrigin>-22527998119.405388</YOrigin> <XYScale>18181.818166159173</XYScale> <ZOrigin>-100000</ZOrigin> <ZScale>10000</ZScale> <MOrigin>-100000</MOrigin> <MScale>10000</MScale> <XYTolerance>0.001</XYTolerance> <ZTolerance>0.001</ZTolerance> <MTolerance>0.001</MTolerance> <HighPrecision>true</HighPrecision> </ProjectedCoordinateSystem>

Then read WKT node from it

Re: Convert ISpatialReference to WKT

AbelPerez — Fri, 17 Dec 2021 15:05:37 GMT

Wow, I didnt know you could do that. Thanks!

Re: Convert ISpatialReference to WKT

KirkKuykendall1 — Fri, 17 Dec 2021 16:48:32 GMT

There's also the ISpatialReferenceFactory.ExportESRISpatialReferenceToPRJFile Method

Re: Convert ISpatialReference to WKT

AbelPerez — Fri, 17 Dec 2021 16:53:55 GMT

I like that one too except you have to write it to disk first.

Re: Convert ISpatialReference to WKT

AbelPerez — Fri, 17 Dec 2021 19:20:13 GMT

As a final edit I took @GKmieliauskas code and made it an extension. Note I use full namespaces so as not to clash with the MS XML functions.

<Extension()> Function SerializeEsri(Of T As Class)(ByVal value As T) As XDocument Dim sr As New ESRI.ArcGIS.esriSystem.XMLStream Dim ir As ESRI.ArcGIS.esriSystem.IStream = CType(sr, ESRI.ArcGIS.esriSystem.IStream) Dim wr As New ESRI.ArcGIS.esriSystem.XMLWriter Dim ser As New ESRI.ArcGIS.esriSystem.XMLSerializer wr.WriteTo(ir) ser.WriteObject(wr, Nothing, Nothing, String.Empty, String.Empty, value) Dim xdoc As XDocument = XDocument.Parse(sr.SaveToString) Return xdoc End Function

Usage:

Private Function GetSpatialReferenceAsWkt(pSpatRef As ISpatialReference) As String If pSpatRef Is Nothing Then Return Nothing Dim xdoc As XDocument = pSpatRef.SerializeEsri Dim xelem As XElement = xdoc.Root.Element("WKT") Return xelem.Value End Function