#498: r.sun2 commissioning trials --------------------+------------------------------------------------------- Reporter: hamish | Owner: hamish Type: defect | Status: assigned Priority: major | Milestone: 6.4.2 Component: Raster | Version: svn-develbranch6 Keywords: r.sun | Platform: All Cpu: All | --------------------+-------------------------------------------------------
Comment(by hamish): Replying to [comment:19 dylan]: > The output looks correct when slope and aspect are specified. One thing I notice about sa_diff_rad.015.jpg is that the diffuse output there seems to incorporate the effects of direct shading, while diff_rad.015.jpg does not. I would ~ guess that the amount of diffuse light reaching a grid cell would be directly proportional to the visible sky. (stable throughout the day; should be independent of aspect (sa_diff.015.jpg is correlated with aspect); perhaps we should try a new r.surf.volcano surface and see how much diffuse light gets into a deep caldera or well, with the only visible sky a small amount directly above) Ultimately I think a formal verification of the model using (multiple) real light meters is going to be necessary, but to get the deployment design right we're going to have to become experts in the algorithm. (e.g. if a light meter is shaded by a reflective wall, its beam will be 0 but will it's diffuse be increased vs a black wall? how many bounces does reflected light follow? just one?) ... here's another pseudo-data test-case, I'll post results once it finishes. {{{ #spearfish (further north than NC so more defined shadows) g.region -d r.mapcalc "undulates = (2 + sin( row() * 2 ) + cos( col() * 2 )) * 500" r.colors undulates color=bcyr nviz undulates DAY=355 time r.sun -s elevin=undulates day=$DAY step=0.05 \ beam_rad=rad_test.und.355.beam \ diff_rad=rad_test.und.355.diff \ refl_rad=rad_test.und.355.refl }}} Hamish -- Ticket URL: <https://trac.osgeo.org/grass/ticket/498#comment:22> GRASS GIS <http://grass.osgeo.org>
_______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev