Micha wrote: > 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).
note that in most places GRASS uses the cartesian convention of theta as degrees counter-clockwise from the positive x-axis, not navigational convention of degrees being measured clockwise from north. (convert between the two with '90-angle') > > 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. (see the help pages for the d.* modules and ps.map, and the cartography section of the grass web site) Hamish _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
