v.lrs.create(1grass)

📦
version 8.5.0 · 11 versions
, in alpine 3.24, ubuntu stonking

💖 v.lrs.create — the GRASS User's Manual glow-up 💖

okay so bestie, welcome to the GRASS User's Manual entry for v.lrs.create, and yes it's giving ✨ vector, linear reference system, network ✨ energy, iykyk.

✨ NAME ✨

v.lrs.create — creates a linear reference system. that's it, that's the whole job, and it ate 💅

🔑 KEYWORDS 🔑

vector, linear reference system, network

📜 SYNOPSIS 📜

v.lrs.create
v.lrs.create --help
v.lrs.create in_lines=name out_lines=name  [err=name]  points=name
[llayer=string]   [player=string]  lidcol=string pidcol=string
[start_mp=string]   [start_off=string]   [end_mp=string]
[end_off=string]   [rsdriver=string]   [rsdatabase=string]
rstable=string  [threshold=float]   [--overwrite]  [--help]  [--verbose]
[--quiet]  [--ui]

🚩 Flags 🚩

  • --overwrite — bestie this one lets output files just bulldoze right over existing files, no cap. use with intention fr fr.
  • --help — prints the usage summary so you're not out here guessing 💀
  • --verbose — verbose module output, aka the module tells you everything it's doing 🗣️
  • --quiet — quiet module output, aka shhh 🤫
  • --ui — forces the GUI dialog to launch, main character energy for your mouse girlies 🖱️✨

🎀 Parameters 🎀

  • in_lines=name [required] — name of input vector map. this is the input vector map containing lines.
  • out_lines=name [required] — output vector map where the oriented lines get written 🦋
  • err=name — output vector map of errors. if stuff goes sideways, the receipts land here.
  • points=name [required] — name of input vector map. this is the input vector map containing reference points.
  • llayer=string — layer number or name, the line layer. Default: 1
  • player=string — layer number or name, the point layer. Default: 1
  • lidcol=string [required] — column containing line identifiers for lines 🔥
  • pidcol=string [required] — column containing line identifiers for points 🔥
  • start_mp=string — column containing milepost position for the beginning of next segment. Default: start_mp
  • start_off=string — column containing offset from milepost for the beginning of next segment. Default: start_off
  • end_mp=string — column containing milepost position for the end of previous segment. Default: end_mp
  • end_off=string — column containing offset from milepost for the end of previous segment. Default: end_off
  • rsdriver=string — driver name for the reference system table. Options: dbf, mysql, odbc, ogr, pg, sqlite. Default: sqlite
  • rsdatabase=string — database name for the reference system table. Default: $GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db
  • rstable=string [required] — name of the table where the reference system will be written. a new table is created by this module, so don't come in expecting an old one to be reused 💅
  • threshold=float — maximum distance of a point to a line that's allowed. Default: 1

🌸 DESCRIPTION 🌸

v.lrs.create generates a LRS (Linear Reference System) from vector line and point data. literally building the whole reference system for you, iconic.

It is highly recommended to work with polylines instead of segmented vector lines — please bestie, listen to the module on this one. The command v.build.polylines creates this map structure. 🧚

📝 NOTES 📝

The mileposts (point) vector map columns start_mp, start_off, end_mp, end_off must be of 'double precision' type. like, non-negotiable. For milepost ordering, it is sufficient to enter increasing numbers into the start_mp column indicating the order along the vector line.

The lidcol and pidcol columns contain the line IDs which relate mileposts and vector line(s) to each other. 🔗

⚠️ heads up bestie: when creating a LRS with this module, any existing rstable will be replaced. it's gone. replaced. no take-backs, periodt.

🍓 EXAMPLE 🍓

This example is written for the Spearfish dataset. let's goooo 🚌

As first step, bus route data are prepared.

# break into segments for correct route selection
v.clean roads_net out=busroute_tmp tool=break
# make polyline for easier line selection by coordinate pairs
v.build.polylines busroute_tmp out=busroute_tmp2
# reverse delete: reduce route map to bus route (enter in one line)
v.edit -r busroute_tmp2 tool=delete coords=590273,4927304,\
590346,4927246,590414,4927210,590438,4927096,590468,4926966,\
590491,4926848,590566,4926798,590637,4926753,590701,4926698,\
590830,4926726,590935,4926751,590993,4926830,590972,4926949,\
590948,4927066,590922,4927182,590957,4927251 threshold=5
# vector line needs to be polyline
v.build.polylines busroute_tmp2 out=busroute_tmp3
v.category busroute_tmp3 out=busroute op=add
g.remove -f type=vector name=busroute_tmp,busroute_tmp2,busroute_tmp3

The result can be visualized:

g.region vector=busroute n=n+100 s=s-100 w=w-100 e=e+100
d.mon x0
d.vect roads_net
d.vect busroute col=red width=2

The vector map 'busroute' needs have an attribute table which contain an integer column lidcol with value be '22' for this example (bus route):

v.db.addtable busroute col="lid integer"
v.db.update busroute col=lid value=22
v.db.select busroute
cat|lid
1|22

A new point map 'busstops' shall contain mileposts (bus stops) along this line (use thresh to define maximal accepted deviation from this line):

# generate points map
echo "590263|4927361
590432|4927120
590505|4926776
590660|4926687
590905|4926742
590972|4926949
591019|4927263" | v.in.ascii out=busstops
d.vect busstops icon=basic/triangle col=blue
d.vect busstops disp=cat lcol=blue

The milepost attributes table needs to be created with specific columns:

v.db.addtable busstops col="lid integer, start_mp double precision, \
            start_off double precision, end_mp double precision, \
            end_off double precision"
v.db.update busstops col=lid value=22

Since the digitizing order of v.in.ascii above reflects the bus stop order along the route, we can simply copy the category number as milepost order number in column start_mp:

v.db.update busstops col=start_mp qcol=cat
# verify table
v.db.select busstops
cat|lid|start_mp|start_off|end_mp|end_off
1|22|1|||
2|22|2|||
3|22|3|||
4|22|4|||
5|22|5|||
6|22|6|||
7|22|7|||
# visualize with start_mp to check order
d.erase
d.vect roads_net
d.vect busroute col=red width=2
d.vect busstops icon=basic/triangle col=blue
d.vect busstops disp=attr attrcol=start_mp lcol=blue

Offsets (start_off, end_off) can be later used in case the route or mileposts get modified. 💫

As second step, the linear reference network is created:

v.lrs.create busroute points=busstops out=route_lrs err=lrs_error \
             lidcol=lid pidcol=lid rstable=route_lrs threshold=50

This creates the maps 'route_lrs' containing the LRS and 'lrs_error' containing the errors if any. The resulting LRS table and map can be shown:

# show LRS table
db.select table=route_lrs
d.vect route_lrs col=blue width=2

👀 SEE ALSO 👀

v.build.polylines, v.lrs.segment, v.lrs.where, 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.create source code (history)

Latest change: Friday May 09 14:33:40 2025 in commit: b356c7e108fcbeca77474c8e83ebec8f1e7b3e4a

Main index | Vector index | Topics index | Keywords index | Graphical index | Full index

okay that's the whole page bestie, you made it to the end and you ate fr fr 💅✨ so here's the cute sign-off: this is all © 2003-2026 GRASS Development Team, the GRASS 8.5.0 Reference Manual, and we were running GRASS 8.5.0 the whole time 🫶🌈⭐ bye ily go build that LRS 👑

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