[GRASS-user] Orthorectification of Historic Aerial Photographs

[Shaun & Melissa Busler]

Thank you so much for your response!  The resources you linked to were very
useful.  The Erdas paper is especially good.  I never heard of MapAnalyst.
I will have to give it a try.

Unfortunately, the focal length of the camera is not on the photo border.
The photo must be too old.  Do you have any recommendations on what focal
length I should try?  It was taken in 1939 for the USDA Agricultural
Adjustment Administration.  If it would help, I could send the image file.
It is about 7 mb in size.

I was using photo2.image as part of the i.ortho.photo UI when I was having
the problems.  It may be because I am using GIS-Knoppix.  If I use GIMP to
measure the fiducial mark coordinates, do I still need to use photo2.image
or do I just use photo.camera?

Thanks!

Shaun

On Sun, Apr 6, 2008 at 6:18 AM, Maciej Sieczka <tutey at o2.pl> wrote:

> Shaun & Melissa Busler pisze:
>
>  1) When is i.ortho.photo going to be available for the Windows binaries?
> >
>
> Dunno. It currently depend on X displays, not easily portable to else than
> Unix.
>
>  2) The historic aerial photos do not have camera calibration files.  I
> > have
> > searched all over and they do not seem to exist anymore.  Is there a way
> > to
> > orthorectify the images without the camera calibration files?  Can I
> > make
> > some assumptions?  If so, what parameters should I enter?
> >
>
> If the DPI at which photos have been scanned is known to you, you can
> measure the principal point and fiducial marks coordinates in any image
> editing software, like GIMP. Interior orientation results will depend on
>  how close is the geometry of the image plane to the geometry of camera's
> optical system, and if/how the photo scan is distorted.
>
> Idea, not tested: you might try using software like MapAnalyst [1] to
> asses the distortion of the image, which can help you guessing genuine
> fiducial marks coordinates.
>
> Then you need the focal length. It often is present on the photo border.
> Or guess it :).
>
>  3) When I tried using photo.2image, I was not prompted with "Look ok?
> > (Y/N)"  so I was not able to mark the fiducials.
> >
>
> photo.2image is not supposed to be used standalone. i.ortho.photo is the
> UI for photo.2image & friends.
>
> There's plenty of info you might find usefull on the net. eg. [2] [3].
>
> [1]http://mapanalyst.cartography.ch
> [2]http://support.erdas.com/focus3/files/Aerial_photo.pdf
> [3]
> http://www.pcigeomatics.com/services/support_center/faqs/oe_general_v10.html#no_fiducial
>
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