Frank,
Some years ago I wrote a module (also called r.horizon) which I
think does what you want. I never got around to formally
contributing it (must compare with the existing r.horizon and do
so some time). Anyhow, have updated for GRASS 7 and will send you
the code direct - it compiles as r.horizon2 to avoid collision
with the existing module.
Regards,
Mark
Frank David <frank.da...@geophom.fr> writes:
Ho yes, why not. I could use r.viewshed to find the farest part
of the
topography able to see my point and get it's angle mode. The
trick to
find is how to get that cell ?
Best regards,
frank
Le 30/07/2018 à 11:18, balotti....@gmail.com a écrit:
Il 30/07/2018 09:24, Frank David ha scritto:
Hi Andrea,
Thanks for your message. But what is the ground plane ?
r.horizon use
the topography, so nothing is plane (and the earth curvature
tends to
lower the ground).
Yes, what you explain below is what I mean with "ground plane".
I guess as the calculation is done at ground level, the
minimum
viewable horizon cannot be lower than zero. The calculation
should be
done higher than ground level to "see" negatives horizon.
Have you taken a look to r.viewshed? I never tried it but maybe
is
useful for your purposes.
Never mind I will try to create my own r.horizon with
r.transect or
r.profile.
Best regards,
Frank
Best regards,
Andrea
Le 30/07/2018 à 08:47, balotti....@gmail.com a écrit:
Hi Frank,
just my opinion but r.horizon I suppose is targeted to solar
radiation modules and because of that returns only the
line-of-sight
"obstacles" above the ground plane, where direct sunlight may
be
obstructed by obstacles.
best regards,
Andrea Balotti
Il 28/07/2018 15:59, Frank David ha scritto:
Dear all,
It seems that r.horizon in does not return negative
heights. How
it's possible in case of the given point from the
calculation is
done is located on mountain and the horizon around is below
zero
??. I miss something may be...
Thank you for your explanations
Regards
Frank
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Dr Mark Lake
Senior Lecturer in Archaeology
UCL Institute of Archaeology
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