[GRASS-user] r.plane azimuth confusion

[Roger Mason]

Hello,

I'm using r.plane to specifiy the orientation of geological boundaries
as part of a method of producing fake geological maps.

According to the documentation for r.plane the azimuth is taken
counter clockwise from north.  If I specify azimuth=90 and, say,
dip=40 then I expect to produce a plane dipping west.  If the top of
the produced map is north that means the dip is towards the left of a
printed page.  This is indeed what I get.

When I specify azimuth=180 and dip=40 I expect to get a plane dipping
due south, which would be towards the bottom of the page if the top of
the page is north.  However, in this case the plane dips towards the
top of the page.  This seems inconsistent with the first example.

Am i misunderstanding something or is there an inconsistency?

Thanks,

Roger

Grass 6.3.0
Gentoo linux