Getting Cached service scales

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11-05-2010 06:42 AM
egismazeika
New Contributor
Hi,
I have an issue while calculating the scale when using cached map services. Let???s compare 2 LODs of different services:
Resolution: 1,32291931250529
Scale: 5000

Resolution: 0,423334180001693
Scale: 5000

The trick is DPI. The first has default value of 96 while the second is 300 DPI!
So how can I calculate the cached service scales correctly?

Btw, LOD in js and flex APIs has a scale property. Why is it still missing in Silverlight?
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3 Replies
JenniferNery
Esri Regular Contributor
Have you looked at this documentation? http://help.arcgis.com/en/webapi/silverlight/apiref/ESRI.ArcGIS.Client~ESRI.ArcGIS.Client.Map.html

You are right that LOD only exposes Resolution but Scale can also be calculated similar to how Map Scale is calculated:

Map scale = 1 : (ScreenRes pixels/inch * 39.37 inches/meter * (Map.Resolution * conversionFactorToMeters))
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egismazeika
New Contributor
Thank you Jennifer for reply. I have looked very carefully at the Map topic and I find it doesn't answer my question.
My issue has nothing to do with Map or screen resolution. No matter what my screen is I need to get the actual cached scales.

Getting DPI value from TiledMapServiceLayer would be enough, but this property is missing too.
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JenniferNery
Esri Regular Contributor
Oh I sent this link just as a guideline how you can calculate scale based on resolution and DPI, since LOD includes Resolution and your DPI varies, you can use the same formula to calculate the scale.
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