[GRASS-user] Rotate a map display

[Hamish]

Vincent wrote:
> If you need to warp a map for a strict display purpose, IMHO it's
> not to be performed from within grass given that this operation
> makes no sense "geographically".

I agree,

> Don't know what the context is, but if you just have to rotate an
> image output of a map maybe you'd better look towards image
> manipulation tools (e.g. imagemagick and the -rotate option, which 
> can easily be integrated in a script process).

pnmrotate is another that I've used with d.out.gpsdrive and GpsDrive's
gdal_slice.sh script, together with 'g.region -n' to get the convergence
angle. (angle between local projection north vs true north)


render map with PNG driver in GRASS, read course-over-ground from Gpsd
(gpsd.berlios.de) in watcher mode, pnmrotate and pnmcrop, and then use
an image viewer which will update the display when the image changes.
(see grass 7 discussions about that).


Hamish