v.lrs.where(1)

NAME
v.lrs.where - Finds line id and real km+offset for given points in vector map using linear reference system.

KEYWORDS
vector, linear reference system, network

SYNOPSIS
v.lrs.where
v.lrs.where --help
v.lrs.where lines=name points=name [llayer=string] [player=string] [rsdriver=string] [rsdatabase=string] rstable=string [threshold=float] [--help] [--verbose] [--quiet] [--ui]

  Flags:

--help
    Print usage summary

--verbose
    Verbose module output

--quiet
    Quiet module output

--ui
    Force launching GUI dialog

  Parameters:

lines=name [required]
    Name of input vector map
    Input vector map containing lines

points=name [required]
    Name of input vector map
    Input vector map containing points

llayer=string
    Layer number or name
    Line layer
    Default: 1

player=string
    Layer number or name
    Point layer
    Default: 1

rsdriver=string
    Driver name for reference system table
    Options: dbf, mesql, mysql, ogr, pg, sqlite
    Default: sqlite

rsdatabase=string
    Database name for reference system table
    Default: $GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db

rstable=string [required]
    Name of the reference system table

threshold=float
    Maximum distance to nearest line
    Default: 1000

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 vector=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:
# use measuring tool in graphical user interface

SEE ALSO
v.lrs.where, v.lrs.segment, v.lrs.label

LRS tutorial,
Introducing the Linear Reference System in GRASS

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

SOURCE CODE

Available at: v.lrs.where source code (history)

Accessed: Saturday May 09 11:18:43 2026

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