## 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 $