[GRASS-user] Orthorectification of Historic Aerial Photographs

[Markus Neteler]

On Thu, Apr 10, 2008 at 5:29 PM, Shaun & Melissa Busler
<buslers at gmail.com> wrote:
> 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.

You could try 150mm or 305mm. In fact, i.ortho.photo is quite robust,
just try and hope that it converges.

(and/or: Maybe someone on the PROJ4 list knows.)

Markus