4

I have made a mosaic of several old orthoimages. If it's possible, I'd like to do two things with the mosaic.

First item is to remove the edges of the smaller rasters that show up in the mosaic, so that the mosaic is more continuous looking. The edges show up as black strips and kind of break up the mosaic along where individual rasters lay on top of other rasters.

The second item is to try to even out the "color" in the images. These images are black and white and they come from scanning in the original b.&w. photos. Likely an artifact of the film, or maybe the scanning process (although I scanned all of these and did everything the same), one run of the orthophotos appears darker in the mosaic. I don't know if this is possible to fix. And if it is, if it won't mess up the rest of the detail of the mosaic.

While researching this question, another question pointed out tools in Arc that seemed useful. I don't know a lot about working with rasters (or GIS for that matter) and I tried these, but they don't seem to have changed much.

I am open on tools, Arc, R, QGIS, but I need some specific instructions if there is any Python code involved. Here is an image of the mosaic and an inset to point out what I mean about the uneven "color" of the mosaic.

Raster and inset

I tried the methods suggested here and the raster images don't display. Instead, if I am at the full scale of the mosaic, 1:156,888, there is a framework, the "footprint", of the individual rasters, that kind of looks like a skeleton. If I zoom down to one raster, everything is the same shade of grey, no detail or features. FWIW, in the TOC, the Image has values between 2147483647 and -2147483648.

3

For remove black edge:

  1. Goto the layer property of your image layer.
  2. Then go to the symbology menustrip. Note: Do not compute histogram.
  3. Remove check from “Display background value” and “Apply gamma stretch”.
  4. Apply these settings then your black edges are removed.

For set the color of orthoimage Image:

There are two methods of set or change the color of high-resolution images.

  1. Add your image in “Effects toolbar” and set the image as per your requirement.
  2. Or you rectify your image to another format like IMG to TIFF
  • 1
    Thanks for the suggestions. The Symbology is Stretched and those options that you indicated were not selected as default. I tried the Effect Toolbar and it didn't really change the appearance as I hoped. The images are saved as TIFFs and I am not sure how else to edit them at this point. – shea Oct 9 '15 at 13:49
  • What software are you using. Sounds like you are trying to do them in ArcGIS , are you ? – PROBERT Oct 9 '15 at 14:47
  • @PROBERT yes, I am using ArcGIS currently. – shea Oct 9 '15 at 20:00
  • Do you have ERDAS or ENVI. These will take care of it. ArcGIS does not a good job if you do mosaic any imagines. – PROBERT Oct 10 '15 at 23:38
  • or you might want to try gdal that does that...Haven't tried that... – PROBERT Oct 10 '15 at 23:42

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.