topic Re: Mosaic Dataset w/ MrSID Statistics in Data Management Questions

Mosaic Dataset w/ MrSID Statistics

RichardHughes3 — Tue, 05 Nov 2013 15:59:40 GMT

This is a simple task that is becoming too complicated and time consuming for me so I am looking for some advice from the rest of the ArcGIS community. How get statistics in the mosaic dataset for a MrSID raster.

I have 11 MrSID files holding the NAIP 1 meter imagery. The compression ratio is such that converting these images to .tif files would take too much time given my laptop workstation and network storage w/o server.

I've created a mosaic dataset for each raster. 11 mosaic datasets holding one MrSID file each. What I want to do is simple. I need to have statistics in the mosaic dataset so that I can color balance all of the mosaic datasets together.

I have been able to get some populated but others I cannot. What I mean is that when I run any other numerous ways to calculate statistics, the process completes but no values are populated in the properties window. The other method I tried was exporting the statistics of the original MrSID files to xml and importing them into the mosaic dataset holding that raster. This method was sure to work but it did not. The properties still say that the statistics have not been calculated. Refresh.. done.. does not help.

Any suggestions? I tried to make this simple task isolated from the rest of the tasks in my workflow. Ideally I would not create a mosaic dataset for each county MrSID raster file.

Re: Mosaic Dataset w/ MrSID Statistics

JeffreySwain — Tue, 05 Nov 2013 19:04:26 GMT

Consider using the skip factor for the long processing. It is outlined here, but the recommendation is to

identify a reasonable skip factor value is to divide the number of columns by 1,000 and use the quotient (integer) as the skip factor.

Re: Mosaic Dataset w/ MrSID Statistics

RichardHughes3 — Tue, 05 Nov 2013 19:14:20 GMT

Hi Jeff,

Yes, I do use the recommended skip factor of 1000. I have tried estimating statistics since the MrSID rasters already have them and I do not want to recreate them.

What is confusing me is that all of the statistics tools will run, but statistics do not get populated into the properties. I just ran a color balance using dodging 3rd order on a mosaic dataset containing 11 mosaic datasets each holding 1 MrSID raster. All of the original rasters have statistics and histograms calculated. I realize that I should be able to add all 11 MrSID rasters into the same mosaic dataset, but I started with that method and am working on isolating the issue.

The color balance did not change the image, and their is not a color balance to remove from the mosaic dataset. I did not receive any warnings or errors about statistics not being calculated when the color balance tool ran.

Also, when I run the analyze mosaic dataset tool, there are no messages about statistics not calculated.

There seems to be something fishy with the compression. Maybe bad source data during download. I would just hate to have to re-download the images and have the same problem.

Re: Mosaic Dataset w/ MrSID Statistics

larryzhang1 — Thu, 07 Nov 2013 09:41:08 GMT

Richard,

On my understanding, ArcGIS GP tools like �??Building Statistics�?? are not functional for compressed images like SID (ECW and JP2 as well), even though the system does not create a warning message (I am not sure why it does not, bug?).

In fact, it makes sense. In other word, if users plan to use those GP tools like �??color balancing�?? on raster images in MD, it is highly required to decode /un-compress those SID into regular images (saying, in IMG), before moving into MD.

Regards,

+++++++++++
Worth to mention, with color balancing /correction onto 13 images, it is still challenging for ArcGIS 10.x to 'automatically' correct colors among raster images in MD, which mostly will not satisify you.

So, the efficient way is to conduct color balancing via the third-party packages like ERDAS ER Mapper�?� See the discussion 3 years ago at http://forums.arcgis.com/threads/19911-How-to-create-image-service-that-can-be-pansharpened?p=65043&viewfull=1#post65043

Re: Mosaic Dataset w/ MrSID Statistics

RichardHughes3 — Thu, 07 Nov 2013 11:15:49 GMT

Thanks for the information about working with compressed images in MD. I will turn my focus onto exporting as .tif or .img before proceeding. The MrSID compression is great, it would be nice if Esri could tap into the raster statistics or at least be able to import them into MD.

Re: Mosaic Dataset w/ MrSID Statistics

RichardHughes3 — Wed, 20 Nov 2013 20:52:30 GMT

Hey Guys,

I have found that it is best to keep the imagery in MrSid format to save size. Now there is a trick to get the statistics to build. Add the raster into ArcMap. Right click on the image layer and go to the symbology tab. On the Stretch dropdown choose Percent Clip. This will prompt ArcMap to build Statistics.

I hack away at imagery and use this trick all the time now. For some reason calcing stats just does not work reliably.

Good Luck

Richard