topic Re: MeasureAction, ScaleLine returning different results in ArcGIS API for Silverlight Questions

MeasureAction, ScaleLine returning different results

CaleBerkey — Sat, 11 Dec 2021 06:06:17 GMT

I'm learning the Silverlight API (2.2) by building a sample app and incorporating many of the features found in the interactive SDK.

I've noticed a difference in the results returned from the ScaleLine and the MeasureAction measure tool. Please see the attached image, showing that the MeasureAction result in red displays 2 miles, where the ScaleLine displays 1 mile. I can confirm that the ScaleLine is correct, where the MeasureAction results are ~ 1.5-2x inflated.

ScaleLine definition:

            <esri:ScaleLine Margin="5" 
                            MapUnit="Meters" 
                            VerticalAlignment="Bottom"
                            HorizontalAlignment="Left"
                            Map="{Binding ElementName=Map}" />

MeasureAction definition:

                                <esri:MeasureAction AreaUnit="SquareMiles"
                                                    DisplayTotals="True"
                                                    DistanceUnit="Miles"
                                                    MapUnits="Meters"
                                                    MeasureMode="Polyline"                                   
                                                    FillSymbol="{StaticResource DefaultFillSymbol}"
                                                    TargetName="Map"/>

My base layer is the ubiquitous world street map layer: http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer.

Any pointers in the right direction would be greatly appreciated! Interestingly, the results I'm getting are the same as in the interactive SDK - the sample must be incorrect? Additionally, I can return correct results using the 'Line Lengths' sample, but that includes a bit of code, compared to the simple XAML declaration for the MeasureAction sample. Obviously, I'd prefer less code, but it is nice to know I have a viable backup.

Re: MeasureAction, ScaleLine returning different results

RyanCoodey — Mon, 25 Apr 2011 19:39:32 GMT

I think this is due to a know bug with the MeasureAction in Web Mercator in the 2.2 beta... sounds like it will be fixed in the next beta or final. Check out this post: http://forums.arcgis.com/threads/27909-MeasureAction-in-Web-Mercator-Issues...

Hope that helps.

Re: MeasureAction, ScaleLine returning different results

DominiqueBroux — Tue, 26 Apr 2011 12:00:35 GMT

I confirm Ryan's answer.
It's likely a measure action bug which is fixed in final : the web mercator projection was not taken into account and the rounding of the measure was not always the best.

Re: MeasureAction, ScaleLine returning different results

CaleBerkey — Tue, 26 Apr 2011 15:21:20 GMT

Ryan, Dominique,

Thanks for your responses. Good to know I wasn't missing something.

Interesting that the scaleline should work with Mercator, but the measureaction be unable to handle it at this point. Looking forward to ESRI addressing the bug. Also good to know that I'm left with the backup option, which, at least, I can fine tune.

Many thanks.