[GRASSLIST:2945] Re: Photo.camera reference file

[Markus Neteler]

On Fri, Jan 18, 2002 at 09:15:54AM -0500, Kirk Schmidt wrote:
> The command photo.camera is used to set up a camera reference file that 
> provides the camera
> details prior to using orthorectifying an image.
> 
> The format allows the user to set up the fiducial mark coordinates but I 
> am not certain of the units and what they are oriented against?
> Could they be in mm and their distance from the image center (Principle 
> Point)?
> 
> Thanks
> 

Hi Kirk,

please have a look at
http://grass.itc.it/gdp/html_grass5/html/photo.camera.html

Yes, it's mm (as written in the menu).
For the order of fiducial mark you may use your private order.
You just have to be consistent, when you later reference these
fiducial mark with mouse in the screen.
I use to start at bottom left, going around clock-wise. But
that's just a personal preference.

Note, that in GRASS 5.0.0pre3 the precision of i.ortho.photo
was improved in the case, that you use a floating point
elevation model. The former versions where rounding elevations
to whole numbers. However, you need a FP DEM to benefit from
the change.

Hope this helps,

Markus Neteler