Problem georeferencing old aerial images

10-31-2013 05:26 AM
New Contributor
They are just scans. Their resolution is between 2 and 3 ft. They seem to have been taken at 12,000 ft. They are black & white - 400 aerial images. We got them as Mr. Sid files. There are a lot of weird problems. I converted them to jpegs. Each tile (image) is 234 inches across! I resampled them down to a smaller size so each jpeg is 30 mb in size. I think this is still too big for what the images are. Even though the images are black and white, each image has 3 bands. I don't think I have ever seen a black and white image made of 3 bands - very odd. Each band is a little different so I think I need to merge the bands of each image. A co-worker georeferenced an image, saved it as a grid and the grid it became a large file impossible to work with. The georeferenced image would not export as a jpeg.

The bottom line. I want to have each tile as a georeferenced jpeg file (I think). Not everyone here is ready to use a mosaic dataset - so I will have to make the images available as a raster catalog and also mosaic them into a single Mr. Sid file. Now, I would like to use a mosaic dataset to help process the images. Even though I cannot use a mosaic dataset right now to publish the images (long story) I do want to use a mosaic dataset as a workspace and production tool. But the problem is, how do I convert the images to something I can work with? I can't resample the images to a reasonable file size and still have okay quality. I am sure I need to make each image so it is one band, not three (that should help with file size but I am wondering what else I should do). As I mentioned, we tried georeferencing an image and it could not be saved as a jpeg. We saved it as a grid but that became a very large file for some reason. I think each image should be under 10 mb and easy to manipulate. Besides turning the images from 3 band to 1 band, just what should I do to make the files a reasonable size before we georeference them? What things should I do that I might be overlooking?
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2 Replies
MVP Alum
Whenever I need to "reformat" image files from, say, 3 band RGB (24bit) to single band grey scale or pseudocolour (8bit) I tend to use Adobe Photoshop Essentials. Its good at that sort of stuff. Not sure that PS will read in sid files though.
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New Contributor II

I've been working with a similar system.  I've been downloading 1950's imagery of my area of interest from and they are scanned images of original aerial frames.  I've been processing them with agisoft photoscan to make them a seamless orthophoto by cropping out the frame edges and registration marks.  Once they are properly aligned in photoscan I add markers as ground control points.  I'm using GCPs in the older imagery that match my current imagery.  Once properly orthorectified in photoscan, I export the imagery with a world file.  I can drop that into ArcGIS and it matches quite well.

I expect that some of the issue may be that your imagery is true airphotography, and it has not been orthorectified yet.  Do you have some sample images that I could take a look at?

Good luck,