Hi All,
In GRASS Net-work analysis please help me build a
network of fire stations (for demonstration) in an
urban area such that the entire city is covered within
a 5 minutes reaction time.
The SCHEME:
1. The existing fire stations are located as point
data, on the existing urban-roads dataset for the
city.
2. The distance that can be covered in 5 minutes by
the fire-tenders will be plotted from each location of
the fire tender. The distance is not as a crow flies
but, on the existing roads.
3. This will show wide gaps in the urban sprawl where
a fire tender cannot reach within 5 minutes, thus a
scope for locating new fire tender stations such that
any fire accident is within 5 minutes from
fire-tender.
Present GRASS Networking:
1. v.net.iso must do the trick by making patches with
distance that can be traveled in 5 minutes, I believe.
Please let me know any existing examples.
Ravi Kumar
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On 07/06/07 07:16, RAVI KUMAR wrote:
Hi All,
In GRASS Net-work analysis please help me build a
network of fire stations (for demonstration) in an
urban area such that the entire city is covered within
a 5 minutes reaction time.
The SCHEME:
1. The existing fire stations are located as point
data, on the existing urban-roads dataset for the
city.
2. The distance that can be covered in 5 minutes by
the fire-tenders will be plotted from each location of
the fire tender. The distance is not as a crow flies
but, on the existing roads.
3. This will show wide gaps in the urban sprawl where
a fire tender cannot reach within 5 minutes, thus a
scope for locating new fire tender stations such that
any fire accident is within 5 minutes from
fire-tender.
Present GRASS Networking:
1. v.net.iso must do the trick by making patches with
distance that can be traveled in 5 minutes, I believe.
Yes, v.net.iso is precisely what you need.
If you need time distance you have to allocate time costs to the network first. You can create a column cost in your road map's attribute table (v.db.addcol) and thus assign costs to roads which you can then integrate into the v.net.iso calculations using the 'afcolumn' (and abcolumn if you work in two directions) option.
Please let me know any existing examples.
There is an example in the v.net.iso man page which should get you going. You can also check the initial introduction by Radim which is more detailed, but some elements are obsolete (such as using openoffice to add a new column):
http://grass.itc.it/grass57/tutorial/network.html
If these two are not enough, please tell us what precisely you need help with.
Moritz
On 11/06/07 15:34, Moritz Lennert wrote:
On 07/06/07 07:16, RAVI KUMAR wrote:
Please let me know any existing examples.
There is an example in the v.net.iso man page which should get you going. You can also check the initial introduction by Radim which is more detailed, but some elements are obsolete (such as using openoffice to add a new column):
http://grass.itc.it/grass57/tutorial/network.html
If these two are not enough, please tell us what precisely you need help with.
P.S. It would be great if, once you figure out how to do this, you could write up your experience in the wiki:
http://grass.gdf-hannover.de/wiki/GRASS_6_Tutorial#Vector_network_analysis_examples
Moritz