[GRASS-dev] grass6.2?

[Glynn Clements]

Wolf Bergenheim wrote:

> > georectifier: C script for RMS error, updates to v.transform so that it can
> > read or ignore a 5th column (use gcp) in a points file, creation of v.group
> > (if everyone thinks this is a good idea). The last two are for consistency,
> > but not required for functionality. I have everything running as is now
> > except for RMS.
> 
> I haven't followed the discussions about this so closely. Would you mind 
> telling me what it is that you way, then I could maybe whip up a module 
> to do the calculations. Do we have some sort of equation(s)?

See compute_transformation() in imagery/i.points/analyze.c.
Compute_equation() is in imagery/i.points/equ.c. The two I_* functions
which are used are in lib/imagery/georef.c.

However, the use of the I_* functions should be replaced by
GDALCreateGCPTransformer(), GDALGCPTransform() and
GDALDestroyGCPTransformer(). Unlike the I_* functions, the GDAL
functions support 2nd- and 3rd-order transformations, and are based
upon the same code which i.rectify uses.

-- 
Glynn Clements <glynn at gclements.plus.com>