.TH v.lrs.create 1grass "" "GRASS 8.3.2" "GRASS GIS User's Manual"
.SH NAME
\fI\fBv.lrs.create\fR\fR  \- Creates a linear reference system.
.SH KEYWORDS
vector, linear reference system, network
.SH SYNOPSIS
\fBv.lrs.create\fR
.br
\fBv.lrs.create \-\-help\fR
.br
\fBv.lrs.create\fR \fBin_lines\fR=\fIname\fR \fBout_lines\fR=\fIname\fR  [\fBerr\fR=\fIname\fR]  \fBpoints\fR=\fIname\fR  [\fBllayer\fR=\fIstring\fR]   [\fBplayer\fR=\fIstring\fR]  \fBlidcol\fR=\fIstring\fR \fBpidcol\fR=\fIstring\fR  [\fBstart_mp\fR=\fIstring\fR]   [\fBstart_off\fR=\fIstring\fR]   [\fBend_mp\fR=\fIstring\fR]   [\fBend_off\fR=\fIstring\fR]   [\fBrsdriver\fR=\fIstring\fR]   [\fBrsdatabase\fR=\fIstring\fR]  \fBrstable\fR=\fIstring\fR  [\fBthreshold\fR=\fIfloat\fR]   [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBin_lines\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input vector map
.br
Input vector map containing lines
.IP "\fBout_lines\fR=\fIname\fR \fB[required]\fR" 4m
.br
Output vector map where oriented lines are written
.IP "\fBerr\fR=\fIname\fR" 4m
.br
Output vector map of errors
.IP "\fBpoints\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input vector map
.br
Input vector map containing reference points
.IP "\fBllayer\fR=\fIstring\fR" 4m
.br
Layer number or name
.br
Line layer
.br
Default: \fI1\fR
.IP "\fBplayer\fR=\fIstring\fR" 4m
.br
Layer number or name
.br
Point layer
.br
Default: \fI1\fR
.IP "\fBlidcol\fR=\fIstring\fR \fB[required]\fR" 4m
.br
Column containing line identifiers for lines
.IP "\fBpidcol\fR=\fIstring\fR \fB[required]\fR" 4m
.br
Column containing line identifiers for points
.IP "\fBstart_mp\fR=\fIstring\fR" 4m
.br
Column containing milepost position for the beginning of next segment
.br
Default: \fIstart_mp\fR
.IP "\fBstart_off\fR=\fIstring\fR" 4m
.br
Column containing offset from milepost for the beginning of next segment
.br
Default: \fIstart_off\fR
.IP "\fBend_mp\fR=\fIstring\fR" 4m
.br
Column containing milepost position for the end of previous segment
.br
Default: \fIend_mp\fR
.IP "\fBend_off\fR=\fIstring\fR" 4m
.br
Column containing offset from milepost for the end of previous segment
.br
Default: \fIend_off\fR
.IP "\fBrsdriver\fR=\fIstring\fR" 4m
.br
Driver name for reference system table
.br
Options: \fIdbf, mysql, odbc, ogr, pg, sqlite\fR
.br
Default: \fIsqlite\fR
.IP "\fBrsdatabase\fR=\fIstring\fR" 4m
.br
Database name for reference system table
.br
Default: \fI$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db\fR
.IP "\fBrstable\fR=\fIstring\fR \fB[required]\fR" 4m
.br
Name of table where the reference system will be written
.br
New table is created by this module
.IP "\fBthreshold\fR=\fIfloat\fR" 4m
.br
Maximum distance of point to line allowed
.br
Default: \fI1\fR
.SH DESCRIPTION
\fIv.lrs.create\fR generates a LRS (Linear Reference System) from
vector line and point data.
.PP
It is highly recommended to work with polylines instead of segmented vector
lines. The command \fIv.build.polylines\fR creates this map structure.
.SH NOTES
The mileposts (point) vector map columns \fIstart_mp\fR, \fIstart_off\fR,
\fIend_mp\fR, \fIend_off\fR must be of \(cqdouble precision\(cq type. For
milepost ordering, it is sufficient to enter increasing numbers into the
\fIstart_mp\fR column indicating the order along the vector line.
.PP
The \fIlidcol\fR and \fIpidcol\fR columns contain the line IDs which
relate mileposts and vector line(s) to each other.
.PP
When creating a LRS with this module, any existing \fIrstable\fR will be
replaced.
.SH EXAMPLE
This example is written for the Spearfish dataset.
.PP
As first step, bus route data are prepared.
.br
.nf
\fC
# 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,\(rs
590346,4927246,590414,4927210,590438,4927096,590468,4926966,\(rs
590491,4926848,590566,4926798,590637,4926753,590701,4926698,\(rs
590830,4926726,590935,4926751,590993,4926830,590972,4926949,\(rs
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
\fR
.fi
The result can be visualized:
.br
.nf
\fC
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
\fR
.fi
The vector map \(cqbusroute\(cq needs have an attribute table which contain an integer column
\fIlidcol\fR with value be \(cq22\(cq for this example (bus route):
.br
.nf
\fC
v.db.addtable busroute col=\(dqlid integer\(dq
v.db.update busroute col=lid value=22
v.db.select busroute
cat|lid
1|22
\fR
.fi
A new point map \(cqbusstops\(cq shall contain mileposts (bus stops) along
this line (use \fIthresh\fR to define maximal accepted deviation from this line):
.br
.nf
\fC
# generate points map
echo \(dq590263|4927361
590432|4927120
590505|4926776
590660|4926687
590905|4926742
590972|4926949
591019|4927263\(dq | v.in.ascii out=busstops
d.vect busstops icon=basic/triangle col=blue
d.vect busstops disp=cat lcol=blue
\fR
.fi
The milepost attributes table needs to be created with specific columns:
.br
.nf
\fC
v.db.addtable busstops col=\(dqlid integer, start_mp double precision, \(rs
            start_off double precision, end_mp double precision, \(rs
            end_off double precision\(dq
v.db.update busstops col=lid value=22
\fR
.fi
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 \fIstart_mp\fR:
.br
.nf
\fC
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
\fR
.fi
Offsets (\fIstart_off\fR, \fIend_off\fR) can be later used in case the route or
mileposts get modified.
.PP
As second step, the linear reference network is created:
.br
.nf
\fC
v.lrs.create busroute points=busstops out=route_lrs err=lrs_error \(rs
             lidcol=lid pidcol=lid rstable=route_lrs threshold=50
\fR
.fi
This creates the maps \(cqroute_lrs\(cq containing the LRS and \(cqlrs_error\(cq
containing the errors if any. The resulting LRS table and map can
be shown:
.br
.nf
\fC
# show LRS table
db.select table=route_lrs
d.vect route_lrs col=blue width=2
\fR
.fi
.SH SEE ALSO
\fI
v.build.polylines,
v.lrs.segment,
v.lrs.where,
v.lrs.label
\fR
.PP
\fI
LRS tutorial,
.br
Introducing the Linear Reference System in GRASS
\fR
.SH AUTHORS
Radim Blazek, ITC\-irst/MPA Solutions
.br
Documentation update (based on above journal article and available fragments): Markus Neteler
.SH SOURCE CODE
.PP
Available at:
v.lrs.create source code
(history)
.PP
Accessed: Thursday Mar 07 18:15:45 2024
.PP
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.PP
© 2003\-2024
GRASS Development Team,
GRASS GIS 8.3.2 Reference Manual