Need help merging aerial imagery

[ArianneBarton]

Hi everyone, mediocre GIS user here. I have some Ortho imagery files (jpeg2000) that I am trying to merge into one file and am having issues with this. I was able to merge three images from one year of data images together correctly using the Mosaic tool, but I have six images from another year that will not work. I used to Mosaic tool on these as well, and the process was supposedly successful, but now the image that I used as the Target Raster is much larger in size than it was before, but it still looks the same on the map as it did before I used the tool. I looked up different methods of how to perform this function and read about the Merge Raster tool, which by its name seems exactly like what I want, but it required opening the attribute table of the image, which I was unable to do (greyed out). I also tried Mosaic to New Raster, which came back unsuccessful stating that the Spatial Reference needs to be the same for the Target Raster and the Input Rasters. I used the same coordinate system and band numbers for the Target Raster, so I am not sure why I got this message. I tried Mosaic to New Raster again and this time it was successful, even though I changed nothing. Could a more knowledgeable person please explain why this happened and give advice on a more consistent method of achieving results? Thank you.

[SepheFox]

Hi Arianne, are you absolutely sure that the projection/coordinate system is the same for ALL your input rasters, as well as the target raster? When you used the mosaic tool, did you have an extent set in your geoprocessing environments? It may be limiting the result. When you load the rasters into a project, do they all line up correctly where you'd expect? Have you tried zooming in and out on the mosaic result? Sometimes the pyramids don't draw correctly, although the data is there.

[ArianneBarton]

Hi Sephe, thanks for your response. I imported the coordinates from one of the jpegs that I wanted to merge, and all of the jpegs have the same coordinate systems as each other so the information should have been exactly the same. In the successful merges, the images were in the right place, although I did notice some had a slight color change, but the color is not important for this project. I did zoom in on the images to make sure they were correct, and with the unsuccessful merges, the rest of the image did not load when I zoomed in. I don't believe I had an extent set; I just used the default setting for everything except number of bands and coordinate system. I made sure the number of bands in the target raster were equal to the number of bands in the input, and that the coordinate system was the same. Since posting this original question, I have tried to merge two more images using the same methods and have been unsuccessful as of yet.

[SepheFox · Accepted solution]

So, when you load the individual rasters from your unsuccessful merges, do they all appear correctly? Try changing your prcocessing extent to "union of inputs", and see if that helps.

[ArianneBarton]

Hi Sephe, it worked! I tried it with the Mosaic tool at first and got the 99999 error, but when I did it with Mosaic to New Raster, it worked fine. Thanks!