Mosaic Dataset Issues

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10-28-2013 10:31 AM
BryanFeger
New Contributor
Hello All:

This is my first post on this forum and I would like to apologize in advance for it being a lengthy one. I also would like to apologize for the fact that my knowledge of GIS is not too vast. So, please bear with me.

Anyways, I am working on a project that requires an extensive amount of GIS work. Basically, the company I work for has been provided GIS data from a couple of different companies and have been asked to do a land impact analysis using their data. One piece of the data that was sent to us was imagery. One of the companies had aerial photography flown in Feb. 2013 of the project site. There is a massive amount of data, as it covers a large landbase. There was so much data that they had to send our company an external hard-drive that contained the information. We then placed the information on our network and sent the hard-drive back to them.

Within the main folder, there are four other folders. Two of the folders appear to contain the individual aerial photos in a .tif format. However, there seems to be other file types within these folders; such as .tif.aux.xml, .tif.xml, .tif.ovr, .rrd, and .aux. The third folder is a geodatabase folder and the final folder is an Overviews folder.

So, my work partner and I compiled all of the information that was provided into a .mxd project using ArcMap 10.2. When we brought the geodatabase file containing the imagery into the .mxd, the only thing we would see is a checkerboard pattern. So, we tried removing it from the .mxd and then brought it back in with no luck; the checkerboard pattern was still there. So, doing what any person does when they need answers to a problem, I googled "checkerboard pattern in ArcMap". I then began to learn about mosaic datasets and determined this is what I am dealing with. So, I have tried following advice in a couple of posts I have seen where people had similar issues. Mostly, I have tried to "repair mosaic dataset paths". I also ran the "analyze mosaic dataset", had some warnings and errors reported, and tried to fix them with no luck at all. Some of the Errors and Warnings that ArcMap shows are pixel type of the raster are outside the allowable range, the footprint of the mosaic dataset contains too many vertices, the overview raster dataset referenced has not been completely processed, and the mosic dataset item references files that are inaccessible.

One thing that I notice about my problem compared to similar problems I have read about is no matter what scale I am at in ArcMap, I cannot see the images. Some people said if they were at a large scale they could see the images, but not at a small scale; and some people had the opposite problem. I cannot see the images at all; just checkerboards. I should say, if I turn on the footprints and boundaries layers I can see those. Just no image. So, this indicates (to my understanding) that the mosaic dataset within the geodatabase file is not referencing the overviews nor the individual images. Am I understanding this correctly? It seems that I need to repair the paths that the data is being read from, but my attempts to do this have failed. So, when I run the "repair mosaic dataset paths" what file am I suppose to reference?

Again, I would like to apologize in advance for the length of this post. This is the first time I have dealt with mosaic datasets, I am quite confused about how they work/how to get them to work, and my bosses are counting on me to get this to work correctly. So, if anyone has any suggestions about how to fix my issue I am all ears and would greatly appreciate your input.

Thank you very much,

Bryan
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17 Replies
brucesimonson
New Contributor III
Disappearing imagery at various scales?  This sounds reminiscent of something I encountered a while back.

First though, I would make sure that the mosaic dataset is visible at all scales.  Right click the layer in the table of contents, pick "properties" from the bottom of the list, pick the "general" tab, and make sure the radio button for "display at all scales" is selected.

If that's right, here's what I had to do, with an earlier version of ArcMAP (10.0).  From an email, I wrote to a colleague at the time:


[INDENT]I was able to figure out how to get rasters to show up, when they seem to go away at small scales.  It appears to be a pyramid problem.

Two steps:  You have to (1) delete the existing pyramids, and then (2) rebuild them.  At least, this worked for me.

To do this, you'll need a tool in the toolbox:  under �??Data Management | Raster | Raster Properties�?�, you�??ll find �??Build Pyramids�?�.

Step (1)  Delete existing pyramids:  Execute this tool, enter the problem raster data set, and then click �??Environments�?�.  Choose �??Raster Storage�?�, make sure �??Build pyramids�?� is checked, and, in the Pyramid Levels, enter �??0�?� (zero).

Click okay, and okay, again, to execute the tool.

Step (2)  Rebuild the pyramids.  After step one is done, run the same tool again, with the same raster, but this time, make sure the �??Build pyramids�?� check box is checked, but leave the pyramid levels blank.

Click okay, and okay, again, to execute the tool.

I know, it�??s weird.  First time, with �??0�?� levels means �??delete pyramids�?�; the second time, with �??blank�?� for levels, means, �??rebuild them�?�.  [/INDENT]


Maybe this will work for you.  Good luck.

Cheers,
-Bruce
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BryanFeger
New Contributor
All - Thank you for all of your replies and suggestions to fix my issue. I greatly appreciate it.

So I messed around with the imagery a little more last night with no luck. If anything, I may have gone backwards. Before, I could zoom in to a large scale and see the black and white checkerboard. After last night, when I zoom to a larger scale than 1:4000 the checkerboard pattern is completely gone, and no image. Before, I could see at least the checkerboard.

So I decided to run the "Analyze Mosaic Dataset" this morning to see what kind of warnings and errors would be reported. I have attached an image of the results. I understand that all of these can definitely be an issue; but, if there is anything in this list that catches someone's eye as the glaring issue I would greatly appreciate someone pointing that out to me.

mvolz47 - So, based on what you are saying, I should see two paths when I run the "Repair Mosaic Dataset Paths"; one for the .tif images and one for the overviews. The problem is, when I run the "Repair Mosaic Dataset Paths" I only see one path, and can only choose one path. On top of that, it doesn't give any indication as to what path it is suppose to be; .tif images or the overviews. So, I don't know how to set the paths for each of these items when it seems like I have to option to set one path. I apologize for my lack of ability to better describe what I am seeing. I hope you understand what I am trying to say. Thank you for the help.

Bruce - Thank you for the suggestion. I may have to give that a try. So, do all mosaic datasets have pyramids? The only reason I ask is I believe I was reading a forum thread last week that someone said they don't use pyramids with their mosaic datasets, or there are times when you should use them and times you should not. If this is the case, how can someone tell if their mosaic dataset has pyramids?

Neil - So, looking at the files that contain the raw images, I have somewhere around 65 GB of images!! I imagine that is going to take a significant amount of time to make my own. Any thoughts on how long this could take? The only reason I am asking is because the office I work in has one ArcMap license, and it needs to be shared. If this is something that could take all day to make, I may put off trying to make my own until the weekend when no one will be using it. Thanks for the help.
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MichaelVolz
Esteemed Contributor
Bryan:

You have a lot of issues with your Mosaic Dataset, all of which I have never seen before.  I would try to take a few images that you know are adjacent to each other and make a small mosaic dataset from just those images including creating new overviews which I would store in a new file geodatabase.  I would then see if the images display correctly at all scales.  You could then begin adding more images to this mosaic dataset and then update the overviews to reflect the additional images.  I would recommend this approach as a way to learn mosaic datasets since you are a beginner and I would not dive into the deep end of the pool if I did not at least know how to swim.
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BryanFeger
New Contributor
mvolz47 - What is funny about that (at least it is in its own way) is this list is quite a bit shorter than it was before. It seems like you have had some experience working with mosaic datasets. In your opinion, do you think the errors and warnings that I am seeing would have been caused by me copy this mosaic dataset from an external hard-drive from another company, placing the geodatabase with the mosaic dataset in my .mxd, and running the "Repair Mosaic Dataset Paths" multiple times? Or, do you think these would have manifested at the time the mosaic dataset was created?

Also, based on what you have seen, do you believe that I would be better off to try and slowly make my own mosaic dataset? Start with a few of the images, make a mosaic dataset, build the overviews and see if I can get it to work in my .mxd? If it works, I can then start adding more of the images and rebuilding the overviews to incorporate them? I am only asking because the project manager is going to be asking me today if it something I think I can do myself or if we need to start asking people some questions. I need to be able to definitively give an answer of either I can do this, or we need help.

I have two folders that contain the .tif image files, but these aren't the only file types in there. In one of the folders each .tif image has multiple file types associated with it. For example, one of the tif images is named Segment-10_corridor_10682_2836.tif. The other files associated with this .tif image are:

Segment-10_corridor_10682_2836.aux
Segment-10_corridor_10682_2836.rrd
Segment-10_corridor_10682_2836.tif.xml

In the other folder, as an example, I have a file called I5_corridor_fy13_0001_.tif. Associated with this file are:

I5_corridor_fy13_0001_.tfw
I5_corridor_fy13_0001_.tif.aux.xml
I5_corridor_fy13_0001_.tif.ovr
I5_corridor_fy13_0001_.tif.xml

Are these associated files there because they are part of the existing mosaic dataset? Will the associated files have any affect if I read the .tif files directly from these folders for the mosaic dataset I will create? If so, do I need to copy all of the .tif files into a new folder and then start adding the images to a mosaic dataset from the new file?

I apologize for asking all of these questions (of which may seem stupid or trivial) but I need to have a pretty good idea of how much work I am going to have to put into this to make it work. The project manager is going to be asking me these questions and I want to have some better answers than "I don't know" or tell them that it won't be that much work and then it takes me days to get it done.

So again, I apologize for all of the "beginners questions" and thank you all for your help and suggestions.

Bryan
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MichaelVolz
Esteemed Contributor
Bryan:

I would create a mosaic dataset with just a few images (5-7) and build the overviews, making sure it is viewable in ArcCatalog and ArcMap at all scales so you know if was built correctly.  Then extrapolate the time for that number of images to the total number of images to give your manager an estimate of how long it will take you to rebuild the complete mosaic dataset.
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BryanFeger
New Contributor
mvolz47 - Thank you for the suggestion. My biggest concern at this point is the questions I have about the .tif files and the other files that are associated with them that I asked about in my last post. Can I reference those files directly from the existing folders, or do I need to copy the .tif files into their own folder and then reference them from the new folder?

Bryan
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MichaelVolz
Esteemed Contributor
You should just be able to add files from a workspace (directory containing the tif file and the other associated files) and they should all be automatically utilized by the mosaic dataset.
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BryanFeger
New Contributor
Okay, so I can create a new mosaic dataset and reference the .tif files from the existing folders. Sounds like a plan. I will give it a try and see what happens. Thank you very much for all of the help.

Bryan
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