I'm writing a Silverlight app that consumes some map services from ArcGIS Server 10.0 SP2 and I have about 15 layers of historical imagery I would like to give the user access to. This imagery doesn't change and I'd prefer to use a cached map service so the user gets a smooth panning/loading experience.

The catch is the user needs to be able to have any two layers overlaid on each other so they can blend between the two.

I can see two options to do this:

  • Create 15 cached map services, one for each layer
  • Create one multi-layer cached map service

I've read several threads where it has been stated that multi-layer caches are not for web applications (and it appears they use the DynamicMapService from the API so they may not even satisfy all my requirements).

I'm sure this isn't an unusual situation to be in and I'm wondering what the typical solution might be. Right now the layers are dynamic layers and it doesn't provide as smooth a user experience as I'd like.

2 Answers 2


If you can afford it, get the image server extension and use a time aware mosaic to create a time aware image service. Performance is near that of cached services without the same space consumption and all that time caching.

  • We have the image server extension now, we're using it to serve the mosaic datasets. I'll look into the time aware mosaics, thanks! Aug 11, 2011 at 23:16

We use many dynamic and cached layers together to display information in the application we wrote. Each service is treated as a layer and the user has the ability to turn on/off most of them.

In terms of blending, it should be fairly easy to allow the user to set a transparency level (or, set it yourself in the application) on one or more layers so that they can see more than one layer at a time on the map.

And, no, I would not use a multi-layer cache. I've not seen a good use for that type of layer; dynamic layers when needed for frequently changing data and cached layers for less-frequently changing data works for us.

  • I don't mind creating a separate map service for each image however it doesn't strike me as an ideal situation. Right now the layers are grouped by map service so splitting them up would force me to write some layer specific code that will consolidate them back into a group in the legend. Aug 11, 2011 at 23:24
  • @Ron If your layers and layer pairings aren't going to change (or change infrequently), you could use a statically generated legend (if groupings and the legend are the only reason that you'd need to consolidate them). Aug 11, 2011 at 23:43
  • The layers need to be completely dynamic as people will be able to build their own maps and save/load them with the layers they have selected. It would be a good solution otherwise but I think I might be stuck with the complicated solution. Thanks! Aug 12, 2011 at 14:23

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