flex viewer 3.6, using existing map cache tiles at large scales lod

Question

Hi,

I have set up my viewer config to allow users to zoom up to scale 141,
My basemap map server cache tiles however only go up to scale 1128,
As expected, once I zoom closer than the 1128 scale, my map will go blank, because no data exists for these levels.

Is there a way to use the same 1128 cached tiles at the larger scales as well? Meaning, instead of giving me a blank map, just give me the tiles from the 1128 scale?

Your help would be much appreciated

Pieter Holtzhausen

BjornSvensson · Answer

...clarify if this is something that is still being worked on?

No, there's no current plans to add that to the Flex API.

AntGiles · Answer

Pieter,

At the user conference last year one of the flex sessions mentioned the ability of zooming past the lowest zoom scale as an enhancement that was being worked on:

http://proceedings.esri.com/library/userconf/proc13/tech-workshops/tw_280.pdf

But this has not seemed to have materialised in any of the releases since, maybe Bjorn or one of the flex team could clarify if this is something that is still being worked on?

Regards

Anthony

TrevorWeiland · Answer

As far as I remember, this was a limitation of the map service responding to the specific request.  This may have changed with 10.1+ but in earlier versions the map service request was either answered correctly or it responded with nothing.

That is, if the viewer is asking for 1:141 scale tile and the service isn't set up to respond with that exact scale tile then the service responds with nothing (or an blank PNG?).  The server doesn't know how to substitute the 1:1128 tile for the missing 1:141 tile so that the viewer can display that.  I doubt the viewer could be programmed to handle the non-standard request.  This may have been a ADF problem but I think rest has it too.

However, I ran into the opposite problem a couple of years ago (v9.3.1) using a tiled WMS/WFS service.  The service always responded with a dynamic map because the JS based request to the service was different than how I had set up my tile scheme (the projection requested was different than the service).  I matched the service projection to the one the application was expecting (outside vendor's application) it started using the cache (a really good thing over a slow cellular network).

ArcMap's communication is more robust and ArcMap performs the substitute request when it's denied the tile it needs (which is why you're not limited to the tiled scales in ArcMap).