[GRASS-user] grass : how to do Isochrone maps?

[Moritz Lennert]

On 04/12/14 10:12, image93 wrote:
> Hello,
>
>   I would like to make Isochrone maps with grass(time and distance
> calculations)
>
> 1 / Could you tell me how to do that with grass please?

In GRASS7 You can use the extension v.isochrones [1].

But this is just a script which provides some fancy packaging r.cost. 
You can look at the source code of the script [2] to see the details.

>
> 2 / A 'road graph' should be compulsory. Do you know where we can get one?
>

It all depends on the region you are working in, but as starters try 
OpenStreetMap.

Moritz


[1] http://grasswiki.osgeo.org/wiki/AddOns/GRASS7/vector#v.isochrones
[2] 
http://trac.osgeo.org/grass/browser/grass-addons/grass7/vector/v.isochrones/v.isochrones.py