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Mosaic dataset image not displaying at proper extent

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08-20-2013 02:00 PM
CharlesBanks1
by
New Contributor II
‎08-20-2013 02:00 PM
Hi All,

I have a situation where many image tiles were georeferenced, and a mosaic dataset created for these images, the image has spatial values. However, when viewed in ArcCatalog the mosaic image is not being display at its supposed actual extent.; neither can it be displayed in a vierwer above a scale of 20,000. Any ideas?
4 Replies
CharlesBanks1
by
New Contributor II
‎08-21-2013 04:13 AM
I did build footprints and overviews but the image is only being displayed at a 20,000 scale and not at all scales. Any help?
0 Kudos
EricRice
by Esri Regular Contributor
Esri Regular Contributor
‎08-21-2013 10:37 AM
Hi Charles,

If you have overviews built and it doesn't display at 20000, 25000, 30000, etc... but does display at 19000, 15000 and larger map scales (remember smaller #'s = larger map scale) then the issue is related to the values in the MaxPS field of the footprint layer.

For example, I have a mosaic dataset of elevation for the whole lower 48 (10m source).  After optimizing it with overviews I can do a zoom to layer on the image sublayer of the of the MD and it will display.  Zoom to Layer takes me to a map scale of 1:29,524,719.  As I zoom out it continues to display (overviews), but at a certain scale (~1:52,590,000) the image sublayer will turn off.  This is the expected behavior. 

The behavior is controlled by the MaxPS field in the footprint table.  To continue my example above, my top overviews have a MaxPS of 13914.93635.  Per the product documentation  (Scale = Cell Size * 96 / 0.0254) we find that Scale = 13914.93635*96 / 0.0254.  The equation results in a scale of 52,591,885.41.  That is precisely when the image sublayer will stop drawing.  My data is in Meters, so it's really straight forward.  The link below has the formulas needed for other units as well as a full explanation of the MinPS/MaxPS fields and their roles.

Cell size ranges in a mosaic dataset

You need to determine the map scale you want the image to draw at (or stop drawing at) and then calculate the MaxPS value that will make it draw at that scale.  You essentially override the existing MaxPS value with your own cell size to force it to draw at your desired scale.

Best,
Eric
ScottTaylor3
by
New Contributor III
‎10-22-2015 06:28 PM

It occurs to me that it would be good to have a presentation scale in the dialog box when creating the pyramids or overviews or when creating the dataset originally so that the user can expect to see the display at a known scale.  I've searched for days trying to sort out why my mosaic would not display above a certain scale!