[GRASS5] Datum transformation with r.proj

[Paul Kelly]

On Tue, 5 Oct 2004, Joel Peter William Pitt wrote:

> (Note, perhaps the man page for r.proj should be changed to
> mention that it automatically does datum transformation,
> rather than "supporting" it. Since I wasn't sure if there were
> meant to be some missing parameters or what....)

It 'supports' it in the sense that if the projection information files for 
both locations define a datum, then a datum transformation will take 
place. But there is no easy way for r.proj to know whether a datum 
transformation is happening or not---it all takes place inside the PROJ.4
library.

You can use 'g.proj -d' (in 5.7) to verify if a location supports datum 
transformation (i.e. has a datum correctly defined).

Paul K