Scanned Oblique Aerials

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05-12-2020 06:17 AM
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New Contributor

Hi there -

I am a research librarian with some skills in GIS but I have a problem I am not sure how to solve. I have approximately 150 oblique aerials from 1958-1960 that have been scanned as TIFFs. Each photo is approximately 50MB. I would like to create a web based atlas that genealogists or researchers could use that would deliver these images, like in an oriented imagery catalog. However, I don't know the best way to go about preparing such a project. Some of the questions I have are:

  • Should I convert the TIFFs to jpgs?
  • Should I reorient the images 90 degrees so they reflect a true north orientation? Since the aerials were taken at a certain angle, I find in rotating them they become more difficult to interpret.
  • I need to geo reference them and are there good tutorials for handling an oblique image?

Are there any good tutorials for working with older images. Oh, the coverage of these aerials is not continuous across an area. These were aerials created in the City of Tampa for specific properties that were either being annexed or under some type of government review. The aerials are piecemeal in their coverage. 

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Esri Notable Contributor

Hi Terry Eagan‌ 

Hopefully somebody in the Imagery and Remote Sensing‌ space can provide some tips, guidance, and/or resources!

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Regular Contributor

The optimum solution to this would be to perform 'resection' based on measuring a set of control points. This would then compute the camera frame center and orientation angles. With these the images could be added to oriented imagery. Resection for oblique imagery is currently not available (but something I'm hoping we can add soon). In the mean time the best is to use the georeferencing tools in ArcGIS Pro and for each image measure at least 4 control points (preferably near the corners of the image) and then use the projective transform.  (Use Save not SaveAs to append the images with the transform). This way you will be able to approx georefererence the images and in Pro be able to see them in the correct place. Once we add the resection function it should then be possible to publish as Oriented Imagery. In the mean time you could serve as an image service.  (Don't loose the aux.xml that will be put next to the images).  I'll try to add to this post when the resection is added.

Concerning the format. I would suggest for the time being just leaving them as TIF. Ensure you allow the system to build pyramids (use Bilinear sampling). Later when publishing you can change to a better format.