Mosaic Overviews do not display when multiple mosaics are in ArcMap

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05-15-2016 11:53 AM
New Contributor III

I created a mosaic dataset with overviews for 2012 tif images and 2015 tif images that cover same area, are indexed the same way. The mosaics are in different file gdb. When I add either mosaic by themselves into an mxd all levels display correctly. But when I add both of them one will not display any overview levels. Zooming in will display the actual image.

2012 had pyramids built before mosaic was created. 2015 does not have pyramids.

I ran Calculate Item Visibility on both, also tried increasing Maximum Number of Rasters per Mosaic. Didnt help.

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MVP Esteemed Contributor

from here Mosaic dataset overviews—Help | ArcGIS for Desktop it seems that the pyramids play a role and that is the only difference from the recommended workflow that you didn't use for the second set.  Have you omitted that for a reason?

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New Contributor III

I was thinking if pyramids existed it would use those, otherwise the overviews would just process more levels.

There are 8000+ images so I was hoping I could get away without processing pyramids for all of them. My next action is to extract a subset and process those to see if pyramids

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Esri Regular Contributor

Michael - I can't quite tell what's happening here - can you be a little more specific?

Background:

1) what version software are you running?

2) I assume the source datasets are preprocessed orthos, probably tiled, perhaps edge matched (no overlap), and presumably already color corrected...

3) what mosaic method are you using for the two MDs?

4) do you have footprints calculated?  is "clip MD to footprint" set to Yes?

5) do you have a NoData value defined?

6) is "clip MD to boundary" set to yes?

7) are all datasets (all source data and also both MDs) in the same coordinate system?

Can you clarify:

a) you start arcmap and drag 2012 mosaic dataset (MD) into the map, and everything looks fine?  displays properly at all scales?  then you add 2015 MD into the map and what happens - does the map suddenly go blank?  or 2012 still works properly at overview scales, but 2015 is transparent/missing until you zoom in to full res?  then if 2015 is on top layer, you see 2015 imagery but only when zoomed in below first overview?

b) if you reverse the sequence (load 2015 first) does 2015 MD work properly, until you add the 2012 (added into map 2nd)?  2012 is missing/transparent until you zoom in to full res?

New Contributor III

1) 10.3

2) yes preprocessed and edgematched. both years are tiled the same

3) Do you mean the resampling method? Bilinear Interpolation. If something else I used all the defaults.

4) Footprints calculated. But Always Clip to Footprint set to No

5) No Data value not defined

6) Clip to Boundary set to Yes

7) No. They are in the same state plane zone, but have different Datum (D_NAD_1983_2011 vs D_North_American_1983)

a) Add 2012, displays at all scales. Then add 2015, both display at all scales initially. But after zooming in/out a few times the 2012 will show checkerboard at all overview levels. Have not figured out exact trigger of when it stops displaying. 2012 will still display when you zoom into actual image.

b) Yes if you reverse the order 2015 has the problem. So issue does not appear to be with a specific MD, depends on order added.

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MVP Esteemed Contributor

Did you do a search on the 'checkerboard' thing?  lots of traffic, potential sources of the issue, might be an interesting read, ... for example

https://community.esri.com/message/601907#comment-601907

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Esri Regular Contributor

Michael

It helps to know that you are seeing a checkerboard - that is shown deliberately when an image cannot be accessed so you know ArcGIS attempted to read the file. 


There's an older blog here Does your mosaic dataset look like a checkerboard? | ArcGIS Blog  but it may not answer your problem.

In my experience, the checkerboard is caused by one of these situations:

1) user has run DEFINE OVERVIEWS but not BUILD OVERVIEWS (perhaps either forgot, or did not realize that "define" does not build).  --> source imagery visible, but OVRs show checkerboard - clearly not your situation or you would never see overviews. 

2) images used to exist but either got deleted or moved.  Again not your situation or you would never see overviews. 

3) user does not have permission to read from image directory --> this often exhibits the *reverse* of what you're seeing - e.g. overviews DO display (stored in a shared network location) but then when you zoom to full res, the original source imagery is locked away in a directory your IT manager has not granted access, so you see checkerboard @ full res.  This also does not describe what you are seeing.

You indicate you can *always* access full res imagery, but sometimes you do see overviews, sometimes you do not.  I don't know of any reason ArcGIS would care what else was loaded into the map, so the order of loading MDs should not introduce this problem.  Are you confident that you never see a checkerboard when only one mosaic is loaded?  Similarly are you certain there are never cases where you see a checkerboard, but then later that image succeeds?

It sounds like you have intermittent access to the storage location for the overviews.  Can you verify where source datasets and also overviews are stored, and determine if there are any differences in read permission, max number of connected users, etc.?   

New Contributor III

Cody,

I also wondered about the IT aspect. The imagery/overviews/gdb with mosaic are all sitting on NAS drives (which always seem to cause hidden issues). So I copied the overviews folder and mosaic gdb over to a local drive, but got the same issue.

I extracted a small area (~75 images out of 9200) and did not have the problem. Going to extract a larger set to see if I can reproduce. If not am going to just start from scratch and rebuild the entire state for both years using some of the settings you listed above that I had different.

We are able to work around the issue, really only need the 2012 when zoomed in to source image level.

If I am able to find a solution will post it. But going to take some time to get through it. Thanks for your help.

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Esri Regular Contributor

Michael

thanks - please keep us posted on what you learn.  If I can think of any other possible causes, I'll get back to you.  One note, it sounds like you're managing some large datasets, so if you aren't familiar with our Image Management Workflows, you may find helpful information here: http://esriurl.com/ImageManagement.

Specifically re: these preprocessed orthophotos from 2012 and 2015, we've published some scripts that you may want to consider using to automate your build/maintenance process - see here http://www.arcgis.com/home/group.html?id=b65f2601e0084e32afab3eb488fa8a67&q=preprocessed%20orthos&t=...

(These scripts are in the AGOL Group referenced from the  Image Management Workflows landing page)


Cody B