[GRASSLIST:7033] Re: i.ortho photo help

Maciek Sieczka werchowyna at epf.pl
Mon Jun 6 16:38:13 EDT 2005

I had a similar problem. Here's what I did:
1 my photos where in written in tiff with correct DPI, so I just
2 opened one in Gimp
3 measured distances between fiducials
4 asked Prof. Pitagoras for help, because I had only 4 fiducials (in 
corners) and the photo was fairly rotated
5 image center is 0,0; coords to the left are negative, positive to the 
right; [mm] is the unit required in i.ortho.photo

If your DPI isn't properly stored in the image but you know it, measure 
distances in pixels, translate to inch -> mm.


----- Original Message ----- 
From: "Luca Penasa" <luca.penasa at email.it>
To: "GRASS Users list" <grasslist at baylor.edu>
Sent: Monday, June 06, 2005 8:11 PM
Subject: [GRASSLIST:7029] i.ortho photo help

> Hi everybody... i need some help.
> im going to rectify some ortho photos but i dont have the calibration 
> report of the camera. Clifford J. Mugnier (thanks) said me that the camera 
> that was used to take the photos is a "WILD Heerbrugg camera made in 
> Switzerlan". I really dont have the time to ask for the report that i need 
> but i want to try to rectify the photos anyway. Somebody said me that on 
> the Markus's book there is a section about the matter but i neither have 
> the time to find that book (i need to finish the work im doing as soon as 
> possible). I only have the focus leght of the camera. I also have the DTM 
> to use for rectify. Particullary i dont have coordinates of the fiducials 
> marks that are required by the command i.ortho.photo, i want to try to 
> rectify the images anyway. Is there a way to do that? Is there the 
> possibility to use a similar report? is there anybody that can send me a 
> similar camera calibration report? Is there a "place" where i can find 
> sample information to use?
> At the moment for me is not really important the accuracy of the work, i 
> only need to finish it. How can i do?
> thaks everybody for the help
> Luca P.
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