Hi Frank. Could please help me a bit (...two questions below) Frank Reekers wrote: > the global radiation, calculated with r.sun, seems to be very high in > comparison to PVGIS (Photovoltaic Geographical Information System). > - r.sun for 14. Feb: ~2363 Wh/m² per day > - PVGIS: 1330 Wh/m² per day Irradiation on horizontal plane for > february on average > > Below the detailed steps I did in GRASS and with PVGIS: > 1. PVGIS: > a) http://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php -> search for > location 'Osnabrueck, Germany' -> choose monthly radiation -> click > calculate -> the output table shows 1330 Wh/m² Irradiation on horizontal > plane for february. > > 2. GRASS > a) Take an existing DEM with the resolution of 1m and set all z-values > to 68m to have a completely horizontal plane: > GRASS 6.4.0RC6 (GRASS)> r.mapcalc dsxx94c68=dsxx...@permanent*0+68.00
What is the projection that defines the Location here? > b) Set Region > GRASS 6.4.0RC6 (GRASS)> g.region rast=dsxx94c68 > > c) Create slope & aspect: > GRASS 6.4.0RC6 (GRASS)> r.slope.aspect elevation=dsxx94...@permanent > slope=sdsxx94c68 aspect=adsxx94c68 --overwrite > > d) Run r.sun for day 45: > GRASS 6.4.0RC6 (GRASS)> r.sun elevin=dsxx94...@permanent > aspin=adsxx94...@permanent slopein=sdsxx94...@permanent > glob_rad=g45phxx94c68 day=45 --overwrite > > e) Get global radiation: > GRASS 6.4.0RC6 (GRASS)> r.what input=g45phxx94c68 > east_north=3435430.596,5794315.99 > 3435430.596|5794315.99||2362.9213867188 Searching for "Osnabrueck, Germany" in PGIS returns the coordinates: 52.267, 8.053 How were the coordinates transformed to metres (i.e. to 5794315.99, 3435430.596)? > Is there a reasonable explanation for this or did I something wrong? Could it be an location error problem? Kind regards, Nikos _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
