[GRASS-user] Orthorectification of tilted digital camera images

[Markus Neteler]

On Tue, Aug 11, 2015 at 11:37 PM, Blumentrath, Stefan
<Stefan.Blumentrath at nina.no> wrote:
> Dear all,
>
> Although there is a lot of relevant information regarding the
> orthorectification of tilted digital camera images in GRASS GIS online
> (here:
...
> Does up-slope direction of the photo or sky in the photo conflict with the
> orthorectification algorithm?

I have no idea... in general the algorithm is very robust but was
really written for aerial photos.

>
> When it comes to the GCPs I am in principle quite confident that they are
> placed OK. Or do you think that GCPs measured by a hand held GPS are too
> imprecise?

They should be fine.

> However, depending on initial camera settings RMS something like 268, which
> indicates that something is wrong here. If I do not use i.photo.init, the
> image is placed much better (RMS around 10-20), but still pretty poor…

About 10 years have passed that I tried the last time, memory is fading...

Did you figure it out?

...
> Btw: Some of the submodules of i.ortho.photo are not linked to the /bin
> folder in GRASS 6.4.5svn, so I have to start them like this:
> /usr/local/grass-6.4.5svn/etc/i.photo.init

To my knowledge they are intentionally hidden in order to be run from
the i.ortho.photo main menu (in GRASS GIS 6).

Markus