[GIS] Adding pins (graphics) to ArcGIS map in WPF

arcgis-api-wpf

I have a wpf app with an ArcGIS map, I used the extent property to zoom and pan to Canada (the location I want) and added the pins (images) by adding a graphics layer, see code below.

currently I'm using this map:
http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_StreetMap_World_2D/MapServer

I'd like to use this instead:
http://server.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer

the problem is that the pins show up in the middle of the map, the 0,0 location, when I switch to the new map. Are graphics specific to a type of maps or am I adding graphics the wrong way? What's the best way to add images to map?

<Grid x:Name="LayoutRoot">
    <Grid.Resources>
        <esri:PictureMarkerSymbol x:Key="PushPin"
                                  OffsetX="11"
                                  OffsetY="39"
                                  Source="pushpin.png" />
    </Grid.Resources>

    <esri:Map x:Name="MyMap"
              Extent="-125, 40, -60, 60">
        <esri:Map.Layers>
            <esri:ArcGISTiledMapServiceLayer ID="StreetMapLayer"
                                             Url="http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_StreetMap_World_2D/MapServer" />
            <esri:GraphicsLayer>
                <esri:GraphicsLayer.Graphics>
                    <!-- Halifax -->
                    <esri:Graphic Symbol="{StaticResource PushPin}">
                        <esri:MapPoint X="-63"
                                       Y="45" />
                    </esri:Graphic>

                    <!-- Toronto -->
                    <esri:Graphic Symbol="{StaticResource PushPin}">
                        <esri:MapPoint X="-79.5"
                                       Y="44" />
                    </esri:Graphic>

                    <!-- Vancouver -->
                    <esri:Graphic Symbol="{StaticResource PushPin}">
                        <esri:MapPoint X="-123"
                                       Y="49.5" />
                    </esri:Graphic>
                </esri:GraphicsLayer.Graphics>
            </esri:GraphicsLayer>
        </esri:Map.Layers>
    </esri:Map>
</Grid>

Best Answer

Your graphics coordinates appear to be WGS 1984 or spatial reference 4326 so does your extent. You are trying to switch to a map service that is in Web Mercator which is spatial reference 102100.

Just go to this link and look at the coordinates at the bottom and you can see they are different.

http://help.arcgis.com/en/webapi/javascript/arcgis/demos/map/map_currentextent.html

The above link uses the map service you want to switch too. So you need to convert your coordinates from spatial reference 4326 (WGS 1984) to spatial reference 102100 (Web Mercator).

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