Le mercredi 22 avril 2015 12:59:53, Larissa Junek a écrit : > Hello, > I look for a GIS expert who can give a good description of the > trigonometric angle that can be produced when using the GDAL aspect > algorithm in Processing. > I need this description for the user manual 2.8..
Larissa, from the GDAL manual: http://gdal.org/gdaldem.html """ aspect This command outputs a 32-bit float raster with values between 0° and 360° representing the azimuth that slopes are facing. The definition of the azimuth is such that : 0° means that the slope is facing the North, 90° it's facing the East, 180° it's facing the South and 270° it's facing the West (provided that the top of your input raster is north oriented). The aspect value -9999 is used as the nodata value to indicate undefined aspect in flat areas with slope=0. The following specifics options are available : -trigonometric: return trigonometric angle instead of azimuth. Thus 0° means East, 90° North, 180° West, 270° South -zero_for_flat: return 0 for flat areas with slope=0, instead of -9999 By using those 2 options, the aspect returned by gdaldem aspect should be identical to the one of GRASS r.slope.aspect. Otherwise, it's identical to the one of Matthew Perry's aspect.cpp utility. """ Even -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user