Viewshed Analysis With GDAL

Question

I am looking to perform a simple (one observer location) viewshed analysis on a standard DEM using GDAL (either python or .NET bindings).

I have searched, but haven't found any readily available implementation. Can anyone point me in the right direction?

Answer 1

I've used python scripts to run both the r.los and r.viewshed grass commands that Peter mentioned.

The advantage with r.los is that it works straight out-of-the-box with grass6, but is slightly slower to run over large raster DEMs. r.viewshed is a bit of a pain to get running, but is a vast speed improvement on very large rasters. See if the times for your DEM are acceptable using r.los, then give r.viewshed a go if it's taking too long. Here's a quick python example using grass64 r.viewshed, but you'll need to get the python grass bindings working first (see http://grass.osgeo.org/wiki/GRASS_and_Python).

import grass.script as grass

grass.run_command('r.viewshed',
        input='standard.dem',
        output='viewshed',
        coordinate=[observer_x, observer_y],
        obs_elev=1.75,
        tgt_elev=0.0,
        memory=4098,
        overwrite=True,
        quiet=True
)

with a better description of the parameters available at http://grass.osgeo.org/gdp/html_grass70/r.viewshed.html

Answer 2

There is also SAGA-GIS which provides visibility analysis. It has Python bindings.

Answer 3

There is also a QGIS plugin that does this. I can not remember the name of the plugin at the moment, it works, but I find it a little slow.