Shaded relief map

Converts shaded relief .tif to .png and uses that for texture underneath a vector layer.

Sources

• http://bl.ocks.org/mbostock/4707858
• http://gis.stackexchange.com/questions/144535/how-to-create-transparent-hillshade
• http://www.mikejcorey.com/wordpress/2011/02/05/tutorial-create-beautiful-hillshade-maps-from-digital-elevation-models-with-gdal-and-mapnik/
• https://developmentseed.org/blog/2009/jul/30/using-open-source-tools-make-elevation-maps-afghanistan-and-pakistan/
• http://www.gdal.org/gdaldem.html
• http://www.gdal.org/gdalwarp.html
• https://github.com/dwtkns/gdal-cheat-sheet
• https://trac.osgeo.org/gdal/wiki/UserDocs/GdalWarp