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v.lrs.where.1grass

NAME

v.lrs.where

DESCRIPTION

v.lrs.where identifies line id and real milepost+offset for points in vector map using linear reference system.

EXAMPLE

This example is written for the Spearfish dataset (it continues the example from v.lrs.create).

In this example, the 'route_lrs' shall be queried for unknown positions (points, stored in the map newpoints) along the LRS:
# generate query points
echo "590866.15|4926737.0
590933|4927133" | v.in.ascii out=newpoints

v.lrs.where lines=route_lrs points=newpoints rstable=route_lrs
pcat|lid|mpost|offset
pcat|lid|mpost|offset
1|22|4.000000+212.091461
2|22|6.000000+188.112093

# verification
g.region vect=route_lrs n=n+100 s=s-100 -p
d.erase
d.vect route_lrs
d.vect busstops disp=attr attr=cat size=10 bg=white lcol=blue yref=bottom
d.vect busstops icon=basic/circle fcol=blue
d.vect newpoints col=red

# measure distance to previous bus stop
d.measure

SEE ALSO

LRS tutorial,
Introducing the Linear Reference System in GRASS,
v.lrs.where, v.lrs.segment, v.lrs.label

AUTHOR

Radim Blazek, ITC-irst/MPA Solutions
Documentation update (based on above journal article and available fragments): Markus Neteler

Last changed: $Date: 2007/06/28 15:42:47 $

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