MapView Resolution Units Conversion

[LukeCatania]

My maps are in Geographic WGS84.  When I use the getResolution method on the mapview, what units is the resolution in?  Radians?  Degrees? 

How do I convert them to meters?  I tried

AngularUnit.convertUnits(mapView.getResolution(), Unit.create(AngularUnit.Code.RADIAN), Unit.create(LinearUnit.Code.METER))));

but received an error:

com.esri.core.geometry.GeometryException: invalid_call

[IvanBespalov]

Luke,

I'm not sure, but

http://services.arcgisonline.com/ArcGIS/SDK/REST/export.html

dpi 
Description: The device   resolution of the exported image (dots per inch). If the dpi is not specified, an image with a default DPI of 96 will be exported. 

Example: dpi=200

We tried to discuss here about it.