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I have about 30 or so composite rasters in IMG format that I need to 1.) Preserve the date that the raster was created and 2.) Combine all of them. My workflow is:

Step 1: raster calculator, multiply floating raster by 10 so that decimal values are not lost in integer conversion Step 2: convert floating raster to integer Step 3: create attribute tables for the rasters Step 4: Add a field Step 5: Calculate field to add the date which will be taken from the name (the datetimes are in the names) Step 6 create raster mosaic - make sure it is still an integer.

This seems easy enough, but I'm not the best informed when it come to rasters. After step 2 (or step 1 if I multiply it by an integer) I get the raster with an attribute table, but it has lost its RGB coloring scheme. I thought that perhaps I could assign RGB based on pixel values as a step 7 once everything is done (somehow) but the pixel values do not quite match the RGBN individual bands. The range of the values of the new integer dataset is 3760-16180 (meaning the range was 376-1618 before Calculate Raster), which are the same values as the first band only (Red I think) and the composite stretched value range. Why is this? Why does the composite band use only these values as well when there are values lower and higher than this in the other bands? How can I classify the pixels as RGB if the full range for each is not there? Also, if you have alternatives or suggestions to my workflow, please let me know.

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I would just add all of the rasters to a mosaic dataset (requires at least an ArcGIS Standard license), without any conversion. If you want to add info about the date, you can add a field to the attribute table of the mosaic's footprints (not even necessary if the name of the raster file is enough: it is added to the attribute table of the footprints when you load the raster to your mosaic).

Pixel values aren't modified this way, so you shouldn't lose your RGB symbology.

You can then set rules to define which rasters are shown on top, create animations with the Time Slider window, etc. See the Time in a mosaic dataset help topic for details.

  • I created the dataset but when I finished adding rasters to it, the RGB image portion does not show up, though the boundary and footprint do. Do you have any ideas? – Tiffany Oct 27 '14 at 20:35
  • Normally the rasters should be visible if you zoom closer. If they don't, try recalculating the statistics on the mosaic. There is an option to determine at which scales the Image layer of the mosaic is visible, but I don't remember where and can't test this today... – GISGe Oct 30 '14 at 11:55

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