Hi All
I'm doing some tests for scoping a large digitisation project of historical aerial photographs (20,000 6"x6" negatives) and figured I should include steps in the workflow to prepare them for use in Photoscan or similar applications.
Digitised at 16bit greyscale
Levels adjustment (image of clock adjusted separately as it's quite dark)
Align images to template (we'll be using PTGui for this. Only offset and rotation will be optimised)
Output aligned images at fixed pixel dimensions
Keep at 16bit or convert to 8bit?
Anything else I should consider?
Regarding masking in Photoscan, I've done a reconstruction using only the central portion of the image. Is there any significant value in including the side and bottom sections as well? I've only got 4 negatives from a single flight path so I don't have much scope for testing. I can probably get PTGui to calculate a correction for falloff of the lens as well.
And while not related to Photoscan, any recommendations on scanning equipment or services that might do this with specific relevance to photogrammetry? The collection is in Georgia
Quick test :
https://skfb.ly/DNUp