[GRASS-user] r.sun problem

[Hamish]

Hi,

> I am using r.sun -s to calculate solarmaps for each month.
> I wrote a shell script which calculates every 10th day
> (including the shaddowing effect). But something is going
> wrong. I looks like the shaddows are displaced somehow (see
> attachement). Using r.sun2 -s didnt make any difference.
> Curiously once it worked! But although I'm using the same
> projection, location, mapset and DSM - it doesnt work
> anymore.
>  
> I hope anybody could help me out or have any ideas how I
> could solve this problem....I really need these maps.
..... 
> I am using Quantum Gis Version 1.0.2 and GRASS 6.4.0 svn
>   
>  
> The region  of my investigation area is:
>  
> $ g.region -p
> projection: 99 (Transverse Mercator)
> zone:       0
> datum:     
> towgs84=577.326,90.129,463.919,5.137,1.474,5.297,2.4232
> ellipsoid:  bessel
> north:      281981.20714553
> south:      281612.20714553
> west:       -29172.52857137
> east:       -28383.52857137
> nsres:      1
> ewres:      1
> rows:       369
> cols:       789
> cells:      291141


could you provide the exact command line you were using?
are you using r.horizon seeds, or slope and aspect seed maps?
what time step?

By chance I noticed in xpdf if I dragged with the left mouse
button instead of the middle one (to pan) I got an inverse
image which made the effect a bit clearer. With that I notice
that the center-southmost  building in the "ok" map actually
isn't.

how do you run the two different versions? did you compile the
old one? is this the latest SVN? (like younger than a week?)
is QGIS only used for visualization or do you run grass from
the toolbox?

lately we have been running some tests with it*, but in general
I think the new version (ie really upgrade) is in fact better
than the old, if just because you can avoid the slope/aspect
bug now.

[*] see http://grass.osgeo.org/wiki/r.sun
and https://trac.osgeo.org/grass/ticket/498



building shadows is something I'd always wanted to try with
r.sun, interesting to see some results! May I ask if it is
LIDAR elevations or simply by e.g. number of storeys?

also, may I suggest "r.colors map color=grey -e", where the -e
flag may help mute the contrasts a bit.


Hamish