[Talk-in] Mapping the Indian Railway network using high resolution Landsat imagery

Arun Ganesh arun.planemad at gmail.com
Fri Apr 30 11:30:23 BST 2010


If nobody's noticed already, i've been adding a significant amount of
railway lines in Southern India. Infact the entire railway network of Tamil
Nadu and Kerala are in. It should start rendering in low zoom in a week i
guess. You can check out an extract of the railway network processed with
qgis here<http://en.wikipedia.org/wiki/File:Tamil_Nadu_Urban_Areas_and_Railway_Connectivity_Map_(openstreetmap).png>
.

How was the tracing done? Well, i seem to have uncovered a sharpened version
of landsat imagery with which it is possible to identify details like
railroads and major highways, especially if its running through fields/rural
areas. In JOSM, goto the WMS plugin preferences and add the following url to
access the sharpened global mosaic landsat tiles:

http://onearth.jpl.nasa.gov/wms.cgi?&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=global_mosaic&STYLES=visual_low&FORMAT=image/jpeg&

On important thing to note is that the landsat wms layer can be off by upto
100metres, so you might need to reposition the layer using gps tracks first.
The resolution of these tiles are far superior to the default landsat
imagery and you can mark highways, railroads, railway stations, airports,
villages/built up areas, farmlands and waterbodies. I wonder why its not
listed in the WMS plugin by default.

If we can manage to put in the skeletal network of the railways in OSM, it
will be easy to get members from IRFCA involved in adding more details.
There are many of them who are so well versed with the railway network that
they would be able to add station codes and station locations just by
looking at the geometry of the railway lines. And later possibly even set up
a dedicated Indian Railway OSM tile server, like whats available for the UK.
I'm sure a lot of travel sites would be interested in something like that.

-- 
http://j.mp/ArunGanesh
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