Howto:Adding Cliffs To Terrain

(Under construction)

Terrain generated from height data on a grid (e.g. Shuttle mission SRTM data) will tend to smooth out abrupt changes in height, such as cliffs. This is because each point on the grid records the average height in the region of the point, and TerraGear will, by default, smoothly interpolate between these points. So even if the grid height points were true point heights, the change in height is spread over the distance to the next grid point and cliffs become steep (or not-so-steep) slopes. The following procedure describes how to add cliffs back to the terrain.

Step 1: extract cliff data

Open Street Maps records the location of cliffs by attaching the tag "natural=cliff" to line features. Extract these features into a shapefile:

osmosis --read-pbf ../australia-latest.osm.pbf --bounding-box top=-31 bottom=-36 left=114 right=119 completeWays=yes --lp --tf accept-ways ' natural=beach' --tf reject-relations --used-node --write-xml file='WAbeaches.osm'