Dec. Degrees to Web Mercator-GraphicsLayer points appear to "move" different extents

Question

Hi all,
I'm having issues with points I've taken from decimal degrees (from a GeoRSS feed) and plotted on the graphicslayert.   At full extent, the points seem okay when first plotted but when zooming in they appear to "move" geographic locations when changing extents.  Is there something I haven't taken into consideration?  I've tried refreshing the graphicslayer whenever the extent is changed.
Thanks for any help you can offer.

MichaelLacy · Answer

I am using a PictureMarkerSymbol, and I happened to see this post:

http://forums.arcgis.com/threads/16398-Location-of-PictureMarkerSymbol-vs-MarkerSymbol

I have not had a chance to experiment with the offsets, but I will give it a try.  I figured I would post this as an FYI.

MichaelLacy · Answer

I have seen the same thing, even when not using a Web Mercator map.  I have plotted points in WV, which look good when zoomed in, but as I zoom out to the world, they slowly "drift" until they end up displaying in the Atlantic.  Has anyone else noticed this or does anyone know what we're missing?

MichaelMacDonald · Answer

Did you reproject the geometries coming from the GeoRSS feed to WebMercator using the ESRI.ArcGIS.Client.Projection.WebMercator class?

Basically did the following with each of the coordinates:

g = New MapPoint(x, y, New SpatialReference(4326))
mpGeom = ESRI.ArcGIS.Client.Bing.Transform.GeographicToWebMercator(g)