Scanned imagery orthomosaic

Question

Dear all,

My case is:

I’ve got scanned aerial imagery taken in 1940s in Europe. There is no data about camera, lens, film farme size and external orientation. I attached example photo.

I georeferenced the imagery.

How to create na orthomosaic with such imagery? Missing camera and orientation data makes me stuck at the begining of the process. How to set fiducials?

Best regards

Michal

IMG_0161.jpg.jpg

progis99 · Answer

Hi friend !

In my case, my forest service has a lot of them that are very old like 1930's and up to 1950's and they have no  information, so that is why you don't see a lot of them out there... The only way for you is to just georeference in ArcGIS Pro or any other Structure in Motion software like Metashape...

Where did you got your scanned imagery ?

Here is what I found a few years ago when I first started working on aerial photos using ERDAS Imagine Autosync and I had to understand how aerial photos works especially overlap with basemap and maps...

My former co-worker says that some of the aerial photos doesn't align very well... so he did not like AutoSync..

Here is the link to the Switzerland (Swiss) Aerial Photos interactive map and you can play it around and give yourself an idea ... Really Neat https://www.swisstopo.admin.ch/en/maps-data-online/maps-geodata-online.html

University of Wisconsin Geography has really neat interactive map

https://www.sco.wisc.edu/maps/aerial-photography/

MichałWąsikowski · Answer

Thanks Robert.

Initialy I was georeferencing the imagery in a way you said. The downside of this way is you don’t get a perfect alignment this way and what is worst - even when you add a GCP perfectly aligned with ground features, it makes misalignment of one image with 2 or 3 others.

That is why I started to think about doing it in more scientific way.

Is there any way to poduce default data about camera and frames? 
How about external orientation? I guess if imagery is georeferenced then external orientation can be calculated for each image.

progis99 · Answer

Hi,  In the past I use Agisoft Metashape to do this scanned image because it is a lot more accuracy  compare to ArcGIS Pro.  If you don't have it, You still can use it without the information.  My agency had taken it away from me because Metashape is from Russia.  So , now I went back to ArcGIS Pro and keep going.. until my agency decides to restore it or not. They may  replace to a different Structure Motion program.

Basically you need to find the same features on both the scanned and the basemap as possible as you can...It is not perfect.

I usually use about 25 control points and use Spline to do this work..

Let me know if you need any question...