Cache Tiles for ImageService in 10.1 - not using cache to build lower resolution tile

[ArtUllman]

It was my understanding that 10.1 ArcGIS Server will build cache tiles from higher resolution tiles when you publish a mosaic dataset as an image service in 10.1.

I am building a national cache tile layer for imagery based on the NAIP 1M Mosaic Data Set.  I purposely did not not build overviews on the Mosaic Data Set, since this takes a while, and it was my understanding that 10.1 built the lower resolution tiles directly from the higher resolution tiles (rather than going back to the orignal imagery).  I completed the 1:4500 scale tiles, and noticed (using Windows Resource Monitor) that the service was still reading the original source imagery from the mosaic dataset when building the 1:9000 and 1:18000. As I mentioned, I don't have overviews/pyramids on these tiles, so the lower resolution tiles are not building nearly as fast as I would like.

We build a lot of cache tile layers from imagery.  We don't want to build overviews/pyramids if we don't have to.  My understanding was that this was an automatic feature.  I can not find any way to tell ArcGIS Server to use the higher resolution tiles to build the lower resolution tiles. 

My Mosaic Dataset was built based on 10 Mosaic Datasets (1 for each UTM Zone in lower 48).  I don't know if this has anything to do with it.

Thanks in advance.

[GarimaTiwari]

Art,

In ArcGIS Server 10.1,  we have added the ability to cache image services. As mosaic dataset's can have overviews or not, the cache service is built to automatically detect if the source image/overviews at the corresponding cache scale is available or not. If the source data is available then cache tiles are cooked using that, otherwise the caching instances creates cache at lower resolution (L18) using cache tiles present at higher resolution (L19).

-Garima

[ArtUllman]

That was my understanding as well, but it does not seem to be working.  I built a mosaic dataset and did not build overviews.  I published the mosaic dataset and then built cache tiles for level 18 from the image service.  I then built level 17.  I turned on Windows Resource monitor and saw that it was still reading the original source imagery (not the tiles).  I then ran level 16 and saw the same thing.  I am about to build the overviews on the mosaic dataset. I was hoping to avoild this.

Is there anything I can look at or change to force it to use the existing level 18 tiles to build the lower res tiles?

Thanks in advance.

[GarimaTiwari]

In the mosaic being cached, if there is data available at the level being cached (L17 in your case), then it will be used and not the cache generated for the previous scale (L18).
Please make sure that in your mosaic all your imagery is available only at the base level you�??re caching.

[ArtUllman]

Level 18 is fully cached. I did use a shape file to define the area to cache.  Every time I restart the cache build, I see it reading original source imagery....  On the mosaic dataset I ran the compute visibility, but that did not fix it.  I am about to build overviews - which I was hoping to avoid.

[GarimaTiwari]

Art,

The right way is to explicitly set the �??max source cell size�?� parameter in the caching page of the service editor. By default, the value is set to the max visible level of the mosaic dataset and try to draw from the mosaic dataset.

For cache levels that have a finer resolution than �??max source cell size�?�, cache tiles are derived from the mosaic dataset.
For cache levels that have a coarser resolution than �??max source cell size�?�, cache tiles are derived from the previous cache level.

[ArtUllman]

Thanks.  That fixed it.  The �??max source cell size�?� was set to 40 on the service.  I changed it to 1 (for 1 m) and restarted the cache build.  It is now reading from the higher resolution tiles.  That is exactly what I was looking for.  Thank you for your assistance.

Art Ullman