Multiple band composite. How do you know which band is which in composite product?

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02-02-2016 11:36 AM
ChrisM
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@I'm returning to a project I began over a year ago. Of course, this means starting from scratch on a few things. I have several VHR satellite images over an area. My ultimate goal is to have them all together, orthocorrected and pansharpened. These latter tasks are relatively easy, but cumbersome. For example, I had to orthosharpen each separate band image and the panchromatic image separately for each coverage given the nature of the rpc file. My next step is to pansharpen them. However, I need to create a composite. As you know, I can create a file that has all the images linked up (i.e., red, green. blue, nir) and select its output based on what I send through the channels. However, here's the issue, and it seems to be a real issue and not just me. Is there a record that tracks which band is which with the composite product? For example, once I create the composite, I have to tell the pansharpen tool which bands to send through the RGB channels. To keep it simply, I'd just assume create a True Color Composite. However, when you create a composite it does not automatically state where the bands are going and where they are. I've been assuming that they become associated with a number based on how they are loaded into the tool? So, if you list the red band first, it will be 1. But I've never actually seen documentation of this.

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CodyBenkelman
Esri Regular Contributor

Christopher

The short answer, I'm afraid, is "no" - this is one of the many disadvantages to saving intermediate files.  What version of ArcGIS are you using?  Are you familiar with the Mosaic Dataset?  I believe you can do all of your steps in the mosaic dataset to go from raw input to final output in a single step.  That is preferred, especially if there is any resampling involved. 

I would say I don't understand the comment about "...orthosharpen each separate band image and the panchromatic image separately for each coverage given the nature of the rpc file..." so perhaps you have something really unique, but for any standard satellite scenes with RPCs, the ability to extract specific bands, orthorectify, pansharpen, and mosaic (all on-the-fly) is built into the Mosaic Dataset.

If you started down this path but weren't sure what to do, focus on the Raster Type.  If you have data from a specific satellite, you need to load it into the Mosaic Dataset using the correct Raster Type (not the default "Raster Dataset" selection).   Let me know if you need further info on this -

Cody B

ChrisM
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Hi Cody,

Please excuse my delayed reply. I literally haven't tapped the ESRI community since the older forum format. I appreciate your advice on the Mosaic dataset option. I'll give that a shot. Thanks! I figured there was no obvious way to track the images. However, I have found that if you load them into the tool individually and in order then 1, 2, 3, and 4, for example, should be red, green, blue, and nir. But I'll try your suggestion. As to my ambiguous comment, sorry I wasn't clear. I have a bunch of individual coverages I was going to mosaic together over a region. However, the rpc file is specific for the band images for each coverage. So, at least through the steps I was taking, I had to orthocorrected each image separately before the regional mosaic. I suppose I could have also first created a composite and then orthocorrected that product, which would have taken me much less time. But at least now I have a bunch of orthosharpened images. Anyway, I'll try your mosaic method.

Best,


Chris

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