[GRASS-user] Georeferencing old areal photography

James Keener jim at jimkeener.com
Wed Dec 30 07:36:52 PST 2015


I have many scans of old slides from areal photography from 30s/40s,
50s/60s, and 60s/70s. Being interested in rail lines, I (and I was going
to trick^Wask my dad and brother to help) trace out the rail lines found
in each areal photograph, with the goal being to align our traces with
current routes in order to georeference the old scans. While some of the
right-of-way has changed since those times, those cases should be small
enough that they can be handled by hand afterwards.

I realize that not all of these scans are in the exact same orientation,
scale, and skew and will need to use something like pHash (or anything
suggested!) to attempt to find overlap. Part of what I'm trying to
figure out right now is how to do the overlap with the GIS files since
phash would only work if I tile my maps of current lines.

Tiles that don't contain rail lines can be handled at a later date,
perhaps with a similar system attempting to align local roads or via
self-similarity with other tiles since they often overlap a little.

Any thoughts, suggestions, ideas, and advice would be greatly appreciated!

Thank you!

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