AGSGeometryEngine bufferGeometry produces "incorrect" result

Discussion created by flspat on Jun 29, 2012
Latest reply on Jul 2, 2012 by DGoyal-esristaff
Hi All,

I'm calling the AGSGeometryEngine bufferGeometry for a point with small buffer distances of 10-100 meters.  The output polygon is short by about 25%... I'm overlaying these polygons on an imagery base map centered on a football or other sports field and the discrepancy is glaringly obvious. 

The map is Web Mercator and I think this is one of those issues we deal with all the time in ArcGIS programming.  The buffer operation is happening in a projection that's not optimal for the calculation.  I can reproduce the same issue using the Javascript API and the Geometry Service's buffer operation.  That service allows me to specify a "bufferSpatailReference".  When I use a local UTM zone for this parameter, I get polygons that seem much closer to correct if not perfect.

Unfortunately, this app will often be offline a lot of the time so I need to use the local geometry engine not the remote geometry service.  Is there a way to handle this operation in using local engine.  I hope I don't have to write my own buffer functions.... point wouldn't be too bad I guess...