topic Re: Geometry Service Measuring Area and Lengths Sample in ArcGIS API for Silverlight Questions

Geometry Service Measuring Area and Lengths Sample

RobertMEIER — Mon, 11 Jul 2011 18:04:21 GMT

I have been trying to use the AreaAndLengths to meaure with and have been getting bad values.

I looked at the sample - http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#AreasAndLengths

And when I go to a place where I know the area I trace is a squre mile, Johnson County, KS, I do not get the correct measurements.

I tried this same operation with the REST api interface and get the same results. I have posted on the REST part of the forum also.

I have included a screen shot from the sample gallery

When I do the same operation using the Measure behavior sample, I get the correct values. Thumbnail attached.

Any help or an explaination is appreciated

-bert

Re: Geometry Service Measuring Area and Lengths Sample

Anonymous User — Sat, 23 Jul 2011 08:53:06 GMT

Original User: rexhansen

The areas and lengths operation only supports measurements in euclidean space right now. These are only useful if the spatial reference of the input geometries are in a projection that minimizes distortion for the area of interest. You can project the input geometry to a custom hotine or equidistant azimuthal projection to minimize distortion, then call the operation to get areas and lengths. I've attached an example that builds on the sample in the SDK. In 10.1 a couple of additional calculation options will be added to the areas and lengths operation to optimize results. The measure action in the API supports client-side geodesic calculations when input geometry is in Web Mercator or DD, otherwise it assumes euclidean space.