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ArcMap 10.2.2 Mosaic Dataset -- Compression/Resampling Question

Question asked by p_griffith on Oct 13, 2015
Latest reply on Oct 13, 2015 by CBenkelman-esristaff

I've created a NATURAL_COLOR_RGB mosaic dataset using all of the default options for adding rasters, as well as for defining and building overviews. The source rasters are 8-bit unsigned MrSIDs in one of two projections and range in cell size from 0.32 ft to 1 ft; the mosaic dataset is in yet a third projection.

 

 

When I view the imagery at a scale of 1:150, I see the image below:

2015-10-13_9-41-36.png

When I identify the image, ArcMap tells me that I'm looking at the source imagery.

However, when I load the source imagery, I see the image below:

2015-10-13_9-41-52.png

Clearly these two images are not the same.

The first image has been smoothed to the point that I can't differentiate pixels even at a scale of 1:1. The second has clearly delineated pixels that measure 1ft x 1ft, which is the image resolution.

 

What is the mosaic dataset doing to the image?

My intuition is that the mosaic dataset is using the default resampling method (in this instance, Bilinear Interpolation) to smooth the image, but when I look at the help it mentions that the resampling method is used to display the mosaicked image. Does the source image count as part of the mosaicked image? Changing this option does not alter the display in any noticeable way.

 

A second thought is that it has something to do with the cell size tolerance factor, which is currently set at the 0.8 default level.

The original images have a MinPS value of 0. Could this be causing the alteration? If so, how should I alter the value to stop this behavior?

I previously set the cell size tolerance factor to 999 as mentioned in the best practices here, but it resulted in unexpected behavior, so I've shied away from this setting.

 

Is this actually another image?

Disk space is a concern for me, so I would like to create a slim mosaic dataset, if possible. I'm willing to give up pretty, smooth imagery in return for a smaller memory footprint and (potentially) faster transmission speeds. If it is another image, how can I get the mosaic dataset to stop this behavior?

 

Thanks for any and all help in this matter. Of course, if the smooth imagery actually consumes less memory and allows the mosaic dataset to run faster than it would with the unsmoothed imagery, I'm all for it. I just don't understand how it couldn't increase processing time, which is something I'd like to keep to a minimum.

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