topic Re: Mosaic overviews in Data Management Questions

Mosaic overviews

BenLeslie1 — Tue, 15 Sep 2015 14:22:04 GMT

I'm a bit confused about mosaic overviews.

I have approx 65000 tiles of 3-band colour imagery in my mosaic and I'm trying to create overviews so I can pickup on any obvious errors - corruptions, mis-coloured tiles etc.

Basically I'm not getting anything useful out of the tools - it just produces a checker board.

I used the default settings - no. rows = no. columns = 5120. Result = nothing.
So I tried - no. rows = no. columns = 2560. Result = little bits of apparently random checker board.
Ok lets try something more extreme - no. rows = no. columns = 320. Result = if I zoom to the extents of the imagery I get full coverage of checkerboard, but if I zoom-in I just see little bits of checkerboard.

I'm not finding the help docs very enlightening, I'm struggling to understand how the tools work and how the results correspond to the settings, and I don't understand why I'm just seeing chessboard.

If I load the raw overview files into arc it's not much more useful - their total coverage is just a tiny portion of my total imagery coverage (although the content looks correct) -- is 65000 images too much for these tools to deal with?

Any advice on how to proceed?

Arc10.2 Windows 7 64 bit - top end speed and memory.

Re: Mosaic overviews

ModyBuchbinder — Tue, 15 Sep 2015 14:34:52 GMT

Checker board show that the overviews are defined but not build.

You need to use the Build Overviews tool after you define them.

It will take it some time but it should do it.

The default are usually just fine - do not change them.

Have Fun

Re: Mosaic overviews

BenLeslie1 — Wed, 16 Sep 2015 06:49:04 GMT

I have used Build Overviews each time. I have tried again with default settings but I still get a chessboard - except, as before, in one tiny corner where it seems to have worked (less than 1%) (the extent in the overview tool covers the whole dataset).

In the tool messages there is one about "Marking stale and missing overviews" otherwise I don't see anything to be concerned about.