Hi Narelle, Thank you for your message. I tried your suggestion but getting "ArcGIS.Core.Geometry.GeometryObjectException: 'GeometryObjectException: The geometry parameter was of the wrong type for the method.'". I'm working with different types of geometries, Points, Lines and some times polygons as one set for the GeometryBag to get the extent of all in GeometryBag. Think it doesn't like the extents of the points when doing the GeometryEngine.Instance.Union. I added a workaround for the interim where I calculate the xMin, xMax, yMin and yMax from all the geometry extents and use the EnvelopeBuilder.CreateEnvelope(xMin, yMin, xMax, yMax, toSpatialReference) to build the smallest Envelope. Thank you for looking into it. Regards, Martin
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