On 09/23/2010 06:46 PM, nunosousa84 wrote:
yes you're right, my distraction. Well i was able to work it out much more
relaxed now :-) I still think the results from the shaded relief are a bit
odd. For example if use 130º azimuth the river valleys appears above the
near mountains, but if i use degrees between 270 and 0º or between 0 and 90º
the river valleys appear below the rest like it should be. Is it normal? I
We're used to perceiving shadows below and highlights above what is
being lit. The same holds for a hill-shaded terrain. When we see shadows
on a slope, it seems to be south facing, and highlights appear north
facing. So if you "place" the sun at 130° (SE) then you are lighting the
south facing slope, and making it appear north facing, thus causing the
valleys to appear to be hills, and the peaks appear as valleys. We have
a set of ortho-photos that were shot early in the morning (sun in the
east) and a colleague always turns the maps "upside down" (N pointing
down) so that the hills and valleys look right.
The most "natural" looking hillshading is with azimuth between 270 -
315° (W to NW).
will try to post a picture here. Im a bit concerned about this cause i will
create the hidrographic system also (basins, ...). By the way GRASS as any
map composer like QGIS to be able to finish the work (put scale bar, north,
legend, title,...)?
Yes, QGIS is a good choice. GRASS does have a full set of map composer
tools, but some graphic elements require a bit more fiddling to get them
right. Mind you, the results can be quite rewarding.
--
Micha Silver
Arava Development Co. +972-52-3665918
http://surfaces.co.il
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