--- name: "v.lrs.create" section: "1grass" platform: "linux" package: "grass-doc" version: "8.4.1-1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/v.lrs.create" --- # v.lrs.create(1grass) Creates a linear reference system. ## NAME **v.lrs.create** - Creates a linear reference system. ## 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** Allow output files to overwrite existing files - **--help** Print usage summary - **--verbose** Verbose module output - **--quiet** Quiet module output - **--ui** Force launching GUI dialog ### Parameters: - **in\_lines**=*name* **\[required\]** Name of input vector map\ Input vector map containing lines - **out\_lines**=*name* **\[required\]** Output vector map where oriented lines are written - **err**=*name* Output vector map of errors - **points**=*name* **\[required\]** Name of input vector map\ Input vector map containing reference points - **llayer**=*string* Layer number or name\ Line layer\ Default: *1* - **player**=*string* Layer number or name\ 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 reference system table\ Options: *dbf, mysql, odbc, 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 table where the reference system will be written\ New table is created by this module - **threshold**=*float* Maximum distance of point to line allowed\ Default: *1* ## DESCRIPTION *v.lrs.create* generates a LRS (Linear Reference System) from vector line and point data. It is highly recommended to work with polylines instead of segmented vector lines. 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. 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. When creating a LRS with this module, any existing *rstable* will be replaced. ## EXAMPLE This example is written for the Spearfish dataset. 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) Accessed: Monday Feb 24 17:51:17 2025 Main index \| Vector index \| Topics index \| Keywords index \| Graphical index \| Full index © 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual