For slope calculations with lat lon coordinates and elevation units in meters or feet you have to be aware to set the proper "scale (ratio of vertical unit to horizal units)" value. Gdal help recomends using 111120 if vertical units are in meters and 370400 if they are in feet. Seehttp://www.gdal.org/gdaldem.html Hope it helps
Gerardo Jiménez Delgado Instituto de Investigaciones Antropológicas Universidad Nacional Autónoma de México Ciudad Universitaria s/n Coyoacan 04510 Mexico City Mexico 56 22 95 16 Date: Wed, 11 Jan 2012 19:18:51 +0530 From: [email protected] To: [email protected] CC: Subject: [Qgis-user] Slope and area/length calculations with Geographic CRS Respected All, When we have to calculate area/length in polygon/line vector layers we have to convert Geographic CRS of the layer in Projected CRS, and in raster DEM for slope calculations the same is to be done. I am providing continuous free practical trainings to the Government officials in India of 5-6 days on Application of Desktop QGIS in Watershed/Rural Development schemes and in this duration I don't want to put the trainees deep in the matter of Coordinate Reference System and want to do everything in GCS-WGS1984. Can there be any solution presently or in future for calculating area/length in vector and slope etc. in DEM with geographic coordinate system. Regards Harish -- Harish Kumar Solanki, Assistant Professor National Institute of Rural Development (NIRD), MoRD, GoI Jaipur, INDIA- 302006 Email- [email protected], [email protected], Tele-Fax-0141-2209904, Mo.- 09414291732, 09214446732 Website- http://www.nird.org.in, http://watershed.rajasthan.gov.in/ LinkedIn: www.linkedIn.com/in/hksolanki _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user
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