Using the 25m EU-DEM for shading OpenStreetMap layers

Inspired by Vaclav Petras posting about “Did you know that you can see streets of downtown Raleigh in elevation data from NC sample dataset?” I wanted to try the new GRASS GIS 7 Addon r.shaded.pca which creates shades from various directions and combines then into RGB composites just to see what happens when using the new EU-DEM at 25m.

To warm up, I registered the “normally” shaded DEM (previously generated with gdaldem) with r.external in a GRASS GIS 7 location (EPSG 3035, LAEA) and overlayed the OpenStreetMap layer using WMS with GRASS 7’s r.in.wms. An easy task thanks to University of Heidelberg’s www.osm-wms.de. Indeed, they offer a similar shading via WMS, however, in the screenshot below you see the new EU data being used for controlling the light on our own:

OpenStreetMap shaded with EU DEM 25m

OpenStreetMap shaded with EU DEM 25m (click to enlarge)

Next item: trying r.shaded.pca… It supports multi-core calculation and the possibility to strengthen the effects through z-rescaling. In my example, I used:

r.shaded.pca input=eu_dem_25 output=eu_dem_25_shaded_pca nproc=3 zmult=50

The leads to a colorized hillshading map, again with the OSM data on top (50% transparency):

eu_dem_25m_PCA_shaded_OSM_trento_rovereto_garda_lake

OpenStreetMap shaded with r.shaded.pca using EU DEM 25m (click to enlarge)

Yes, fun – I like it :-)

Data sources:

This entry was posted in Blog, Cartography, data, DEM, elevation, GRASS, OpenStreetMap on by .

About neteler

Markus Neteler , a founding-member of the FOSSGIS.de (D-A-CH), GFOSS.it (Italy), and the Open Source Geospatial Foundation (OSGeo), was head of the GIS and Remote Sensing Unit at the Research and Innovation Centre of the Fondazione Edmund Mach, Trento, Italy from 2008-2016. Since then he is CEO of mundialis company located in Bonn, Germany, a startup specialized in open source development and massive data processing. He is author of several books and chapters on GRASS and various papers on GIS applications. Being passionate about Open Source GIS, he became a GRASS GIS user in 1993 and a developer in 1997, coordinating its development since then.

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