Hi All, I have a friction map, a start polygon and an end polygon and would like to find the least cost path, meaning not a corridor but a thin line. To now I've tried both r.cost and r.walk and r.drain eventually, but the result of this latter
r.drain input=friction@PERMANENT output=rdrain_out vector_points=start_line@PERMANENT is a path calculated *within* the start polygon (a closed line). I suppose this is because I don't provide a direction map to r.drain (I'm using GRASS 7). I read: If the *input* surface (a raster map layer) is a cumulative cost map generated by the *r.walk<http://grass.osgeo.org/grass70/manuals/r.walk.html> * or *r.cost <http://grass.osgeo.org/grass70/manuals/r.cost.html>* modules, the -d flag and a movement direction surface *"indir" *must be specified. I assume it's a kind of flow direction or aspect, but what is the physical meaning, and how can I calculate it? Could anyone please provide some further info. Thank you in advance Madi -- Margherita DI LEO Postdoctoral Researcher European Commission - DG JRC Institute for Environment and Sustainability (IES). Unit H03 – FRC Via Fermi, 2749 I-21027 Ispra (VA) - Italy - TP 261 Tel. +39 0332 78 3600 [email protected] Disclaimer: The views expressed are purely those of the writer and may not in any circumstance be regarded as stating an official position of the European Commission.
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