Mosaic Datasets - inconsistent Overview and/or pyramid display resolution?

[Anonymous User]

Original User: andyroo

I decided to explore mosaic datasets as a method of managing large datasets of bathymetric data at varying resolutions. After adding 133 DEMs ranging from 50cm to 10m cell size to the mosiac dataset (all at once), I am seeing inconsistent overview/pyramid display for the finest resolution rasters (50cm and 1m). I attached images showing how these tiles show up at improperly large scales relative to the other layers (highest resolution data are adjacent to the white north image boundary).

I should mention that I am not totally clear about the difference between .ovr and .rrd files, and how they relate to each other. I am wondering if my inexperience with the new .ovr files has created the problem. When I was adding the raster data to the mosaic dataset, under "advanced", I did select "build pyramids", which was off by default.

If I zoom in close enough (>1:4000) then the fine-scale pyramids/overviews show up fine, although the coarser scale ones (15m and 30m) don't go away. But if I am zoomed out past 1:4000, then the coarser .rrd/.ovr obscures the bathy - but only for the highest resolution data layer.

How can I get rid of the coarse display or at least hide it at higher zooms? I should mention also that these coarse scales show up in the DEM mosaic dataset (that I added existing rasters to and built pyramids for) as well as the referenced hillshade mosaic (where I just pointed to the DEM mosiac datast). I generally followed the directions here:

http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009t000000p4000000.htm

except for where I selected "build pyramids" in the advanced settings in the "add rasters" dialog box.


I am trying to determine if I can adjust/rebuilt some overlay or pyramid setting to achieve better display, or if this is a more serious issue with mosaic datasets.

[Anonymous User]

Original User: andyroo

I have confirmed that (1) I can duplicate this by simply following the instructions in the "create mosaic dataset" tutorial I linked to in my previous post, (2) it's not bad overview tiles, but a bad mosaic dataset - the crappy data propagates into geotiffs created by clipping and exporting the mosaic dataset, (3) the problem does not occur when I import a few datasets at a time - at least I was able to import a four files (1m grid, 2m grid, 4m grid, and 8m grid) from a survey where the mass-import made bad data and the Mosaic dataset from those four files looks fine.

Am I posting in the wrong forum?

[AndyRitchie · Accepted solution]

Thanks for your help everyone

<oh wait, it was just me.. Hooray for me!>

After digging through ESRI's "documentation" to find out more about these strange objects called mosaic datasets, I think I figured out what's going on. Has to do with the following fields in the Mosaic Dataset attribute table: MinPS,MaxPS,LowPS,HighPS, and also with the mosaic dataset image mosaic method property (say that 10 times fast).

Apparently, they don't get set to anything worthwhile by default, at least not for multi-resolution irregularly bounded bathymetry. So once you get your LowPS/HighPS,MaxPS,MinPS fields all figgered out, you've gotta go in and tell Arc to mosaic by the LowPS. If you're trying to fill empty spaces with best available data, and you've got sub-pyramids built for all your data layers, it seems that you want your MaxPS set to whatever the biggest setting is for everything else.

But take all this with a grain of salt, this here mosaic dataset beast is still very much alien to me. I feel like I at least got a rope around its neck now though.