[GRASS-user] rectifying digital images

[Markus Neteler]

On Jan 5, 2008 1:56 PM, Vincent BAIN <bain at toraval.fr> wrote:
>
> Le samedi 05 janvier 2008 à 13:44 +0100, Markus Neteler a écrit :
>
> > On Jan 5, 2008 1:35 PM, Markus Metz <markus_metz at gmx.de> wrote:
> > ...
> > > Anyway, digital cameras are apparently not supported in i.ortho.photo.
> >
> > Why this? I did so, using a handheld digital camera:
> >
> >   M. Neteler, D. Grasso, I. Michelazzi, L. Miori, S. Merler, and
> >   C. Furlanello, 2005. An integrated toolbox for image registration, fusion
> >   and classification. International Journal of Geoinformatics. Special Issue
> >   on FOSS/GRASS 2004 & GIS-IDEAS 2004, 1(1), pp. 51-61, March 2005.
> >   PDF: http://ojs.info.gscc.osaka-cu.ac.jp/IJG/index.php/IJG/article/view/103/42
> >
> > > I heard of some tools that can add fiducial marks to digital photographs
> >
> > You can use the photo corners and calculate things yourself using
> > "jhead" or other tools.
>
> You mean pointing corners of the image as four fiducials, then assigning
> them the dimensions of the sensor, in a coordinate system centered on
> the estimated principal point ? If you do that with i.ortho.photo what
> value would you give to the focal length, the one provided by the exif ?

OK, I have added my draft recipe here:
http://grass.gdf-hannover.de/wiki/Orthorectification_digital_camera

Feel free to improve the page.

Markus