topic Re: Real size in Buffers in ArcGIS API for Silverlight Questions

Real size in Buffers

EnriqueIbarra — Thu, 18 Apr 2013 17:06:05 GMT

I'm using the Geometry Service to create Buffers:

gmtrySrvcBuffers = new GeometryService("http://tasks.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer");                 gmtrySrvcBuffers.BufferCompleted += gmtrySrvcBuffers_BufferCompleted;                 BufferParameters bufferParams = new BufferParameters() { BufferSpatialReference = Variables.Mapa.SpatialReference, OutSpatialReference = Variables.Mapa.SpatialReference, Unit = LinearUnit.Meter };

Note that the spatial references are defined from the base Map.

And the MeasureAction to display the radio of a circle:

<esri:MeasureAction AreaUnit="SquareMeters" DisplayTotals="True" DistanceUnit="Meters" MapUnits="Meters" MeasureMode="Radius" FillSymbol="{StaticResource DefaultFillSymbol}" TargetName="MyMap" />

in both cases the units are Meters.

Once buffer created (with a value of 1000, from a text of a TextBox converted to Double, for the radio), I use the MeasureAction and the result is:

[ATTACH=CONFIG]23608[/ATTACH]

What I'm doing wrong? why the measures aren't equals?'

Re: Real size in Buffers

DominiqueBroux — Mon, 22 Apr 2013 06:18:55 GMT

With these buffer params, the geometry service is doing euclidian 2D calculation.
So it's not taking care of the Web Mercator distorsion (about cos(latitude)).

From 3.1, the Geometry Service has a new geodesic parameter in order to generate a buffer polygon using a geodesic distance (but your coordinates have also to be in GCS)

Re: Real size in Buffers

EnriqueIbarra — Mon, 22 Apr 2013 21:12:18 GMT

Thanks Dominique! I've solved the problem. Just used the Spatial Reference of the sample http://resources.arcgis.com/en/help/silverlight-api/samples/start.htm#BufferQuery