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v.net.iso.1grass

NAME

v.net.iso

DESCRIPTION

v.net.iso splits net to bands between cost isolines (direction from centre). Centre node must be opened (costs >= 0). Costs of centre node are used in calculation. Supported are cost assignments for both arcs and nodes, and also different in both directions of a vector line. For areas cost will be calculated along boundary lines.

NOTES

Nodes must be on the isolines.

Center nodes have to be assigned to vector nodes. Nodes and arcs can be closed using cost = -1.

EXAMPLE

Subdivision of a network into areas:
The map must contain at least one center (point) on the vector network which can be patched into with v.patch.
# Spearfish

# start node:
echo "591280.5|4926396.0|1" | v.in.ascii out=startnode
g.copy vect=roads,myroads

#create line map connecting point to network
v.distance -p from=startnode to=myroads out=connect upload=dist column=dist
# fix missing category number:
v.category connect out=connect2 op=add

d.vect myroads
d.vect startnode col=red
d.vect connect2 col=green

v.patch in=myroads,connect2,startnode out=roads_n
v.clean roads_n out=roads_net tool=snap,break thresh=5,0

# specify range of center cats (easier to catch all):
v.net.iso input=roads_net output=isomap ccats=1-100000 costs=1000,2000,5000 nlayer=1
v.category isomap option=report
# ... reports 4 categories:
The network is 4 categories:
cat | distance from point
1 0 - 1000
2 1000 - 2000
3 2000 - 5000
4 > 5000
To see the result, run for example:
d.erase
d.vect isomap col=blue cats=1
d.vect isomap col=green cats=2
d.vect isomap col=yellow cats=3
d.vect isomap col=red cats=4

SEE ALSO

d.path, v.net, v.net.alloc, v.net.path, v.net.salesman, v.net.steiner, v.patch

AUTHOR

Radim Blazek, ITC-Irst, Trento, Italy

Last changed: $Date: 2007/07/22 23:54:59 $

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