.TH v.in.lidar 1grass "" "GRASS 7.2.0" "Grass User's Manual"
.SH NAME
\fI\fBv.in.lidar\fR\fR  \- Converts LAS LiDAR point clouds to a GRASS vector map with libLAS.
.SH KEYWORDS
vector, import, LIDAR
.SH SYNOPSIS
\fBv.in.lidar\fR
.br
\fBv.in.lidar \-\-help\fR
.br
\fBv.in.lidar\fR [\-\fBpruvetcboi\fR] \fBinput\fR=\fIname\fR \fBoutput\fR=\fIname\fR  [\fBid_layer\fR=\fIstring\fR]   [\fBreturn_layer\fR=\fIstring\fR]   [\fBclass_layer\fR=\fIstring\fR]   [\fBrgb_layer\fR=\fIstring\fR]   [\fBspatial\fR=\fIxmin,ymin,xmax,ymax\fR[,\fIxmin,ymin,xmax,ymax\fR,...]]   [\fBzrange\fR=\fImin,max\fR]   [\fBreturn_filter\fR=\fIstring\fR]   [\fBclass_filter\fR=\fIinteger\fR[,\fIinteger\fR,...]]   [\fBmask\fR=\fIname\fR]   [\fBmask_layer\fR=\fIstring\fR]   [\fBskip\fR=\fIinteger\fR]   [\fBpreserve\fR=\fIinteger\fR]   [\fBoffset\fR=\fIinteger\fR]   [\fBlimit\fR=\fIinteger\fR]   [\fBlocation\fR=\fIname\fR]   [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-p\fR" 4m
.br
Print LAS file info and exit
.IP "\fB\-r\fR" 4m
.br
Limit import to the current region
.IP "\fB\-u\fR" 4m
.br
Invert mask when selecting points
.IP "\fB\-v\fR" 4m
.br
Use only valid points
.br
Points invalid according to APSRS LAS specification will be filtered out
.IP "\fB\-e\fR" 4m
.br
Extend region extents based on new dataset
.IP "\fB\-t\fR" 4m
.br
Do not create attribute table
.IP "\fB\-c\fR" 4m
.br
Do not automatically add unique ID as category to each point
.br
Create only requested layers and categories
.IP "\fB\-b\fR" 4m
.br
Do not build topology
.br
Advantageous when handling a large number of points
.IP "\fB\-o\fR" 4m
.br
Override projection check (use current location\(cqs projection)
.br
Assume that the dataset has same projection as the current location
.IP "\fB\-i\fR" 4m
.br
Create the location specified by the \(dqlocation\(dq parameter and exit. Do not import the vector data.
.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 "\fBinput\fR=\fIname\fR \fB[required]\fR" 4m
.br
LAS input file
.br
LiDAR input files in LAS format (*.las or *.laz)
.IP "\fBoutput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name for output vector map
.IP "\fBid_layer\fR=\fIstring\fR" 4m
.br
Layer number to store generated point ID as category
.br
Set to 1 by default, use \-c to not store it
.IP "\fBreturn_layer\fR=\fIstring\fR" 4m
.br
Layer number to store return information as category
.br
Leave empty to not store it
.IP "\fBclass_layer\fR=\fIstring\fR" 4m
.br
Layer number to store class number as category
.br
Leave empty to not store it
.IP "\fBrgb_layer\fR=\fIstring\fR" 4m
.br
Layer number where RBG colors are stored as category
.br
Leave empty to not store it
.IP "\fBspatial\fR=\fIxmin,ymin,xmax,ymax[,\fIxmin,ymin,xmax,ymax\fR,...]\fR" 4m
.br
Import subregion only
.br
Format: xmin,ymin,xmax,ymax \- usually W,S,E,N
.IP "\fBzrange\fR=\fImin,max\fR" 4m
.br
Filter range for z data (min,max)
.IP "\fBreturn_filter\fR=\fIstring\fR" 4m
.br
Only import points of selected return type
.br
If not specified, all points are imported
.br
Options: \fIfirst, last, mid\fR
.IP "\fBclass_filter\fR=\fIinteger[,\fIinteger\fR,...]\fR" 4m
.br
Only import points of selected class(es)
.br
Input is comma separated integers. If not specified, all points are imported.
.IP "\fBmask\fR=\fIname\fR" 4m
.br
Areas where to import points
.br
Name of vector map with areas where the points should be imported
.IP "\fBmask_layer\fR=\fIstring\fR" 4m
.br
Layer number or name for mask option
.br
Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
.br
Default: \fI1\fR
.IP "\fBskip\fR=\fIinteger\fR" 4m
.br
Do not import every n\-th point
.br
For example, 5 will import 80 percent of points. If not specified, all points are imported
.IP "\fBpreserve\fR=\fIinteger\fR" 4m
.br
Import only every n\-th point
.br
For example, 4 will import 25 percent of points. If not specified, all points are imported
.IP "\fBoffset\fR=\fIinteger\fR" 4m
.br
Skip first n points
.br
Skips the given number of points at the beginning.
.IP "\fBlimit\fR=\fIinteger\fR" 4m
.br
Import only n points
.br
Imports only the given number of points
.IP "\fBlocation\fR=\fIname\fR" 4m
.br
Name for new location to create
.SH DESCRIPTION
\fIv.in.lidar\fR converts LiDAR point clouds in LAS format to a GRASS
vector, using the libLAS library.
The created vector is true 3D with x, y, z coordinates.
.PP
For larger datasets, it is recommended to not build topology (\-b flag).
Also, creating a table with attributes can take some time for larger datasets.
.PP
The optional \fBspatial\fR parameter defines spatial query extents.
This parameter allows the user to restrict the region to a spatial subset
while importing the data. All LiDAR points falling into this rectangle
subregion are imported. The \fB\-r\fR current region flag is identical,
but uses the current region settings as the spatial bounds
(see \fIg.region\fR).
.PP
A LiDAR pulse can have multiple returns. The first return values can be
used to obtain a digital surface model (DSM) where e.g. canopy cover is
represented. The last return values can be used to obtain a digital
terrain model (DTM) where e.g. the forest floor instead of canopy
cover is represented. The \fBreturn_filter\fR option allows selecting one of
first, mid, or last returns.
.PP
LiDAR points can be already classified into standardized classes. For example,
class number 2 represents ground (for other classes see LAS format specification
in references). The \fBclass_filter\fR option allows selecting one or more
classes, as numbers (integers) separated by comma.
.PP
Note that proper filtering of the input points in not only critical for
the analysis itself but it can also speed up the processing
significantly.
.SS Decimation
Table with selected percentages of points to keep with corresponding
decimation parameters:
.TS
expand;
lw60 lw1 lw60.
T{
percentage
T}	 	T{
parameters
T}
.sp 1
T{
0.1%
T}	 	T{
preserve=1000
T}
.sp 1
T{
1%
T}	 	T{
preserve=100
T}
.sp 1
T{
5%
T}	 	T{
preserve=20
T}
.sp 1
T{
10%
T}	 	T{
preserve=10
T}
.sp 1
T{
20%
T}	 	T{
preserve=5
T}
.sp 1
T{
25%
T}	 	T{
preserve=4
T}
.sp 1
T{
50%
T}	 	T{
skip=2
T}
.sp 1
T{
75%
T}	 	T{
skip=4
T}
.sp 1
T{
80%
T}	 	T{
skip=5
T}
.sp 1
T{
90%
T}	 	T{
skip=10
T}
.sp 1
.TE
Table with selected fractions of points to keep with corresponding
decimation parameters:
.TS
expand;
lw60 lw1 lw60.
T{
ratio
T}	 	T{
parameters
T}
.sp 1
T{
1/3
T}	 	T{
preserve=3
T}
.sp 1
T{
1/4
T}	 	T{
preserve=4
T}
.sp 1
T{
1/5
T}	 	T{
preserve=5
T}
.sp 1
T{
1/6
T}	 	T{
preserve=6
T}
.sp 1
.TE
Table with selected fractions of points to throw away with corresponding
decimation parameters:
.TS
expand;
lw60 lw1 lw60.
T{
ratio
T}	 	T{
parameters
T}
.sp 1
T{
1/3
T}	 	T{
skip=3
T}
.sp 1
T{
1/4
T}	 	T{
skip=4
T}
.sp 1
T{
1/5
T}	 	T{
skip=5
T}
.sp 1
T{
1/6
T}	 	T{
skip=6
T}
.sp 1
.TE
.SH Location Creation
\fIv.in.lidar\fR attempts to preserve projection information when importing
datasets if the source format includes projection information, and if
the LAS driver supports it.  If the projection of the source dataset does
not match the projection of the current location \fIv.in.lidar\fR will
report an error message (\(dqProjection of dataset does not appear to
match current location\(dq) and then report the PROJ_INFO parameters of
the source dataset.
.PP
If the user wishes to ignore the difference between the apparent coordinate
system of the source data and the current location, they may pass the
\fB\-o\fR flag to override the projection check.
.PP
If the user wishes to import the data with the full projection definition,
it is possible to have \fIv.in.lidar\fR automatically create a new location based
on the projection and extents of the file being read.  This is accomplished
by passing the name to be used for the new location via the \fBlocation\fR
parameter.  Upon completion of the command, a new location will have been
created (with only a PERMANENT mapset), and the vector map will have been
imported with the indicated \fBoutput\fR name into the PERMANENT mapset.
.SH NOTES
The typical file extensions for the LAS format are .las and .laz (compressed).
The compressed LAS (.laz) format can be imported only if libLAS has been compiled
with laszip support. It is also recommended to compile libLAS with GDAL,
needed to test for matching projections.
.SH EXAMPLE
This example is analogous to the example used in the GRASS wiki page for
importing LAS as vector points.
.PP
The sample LAS data are in the file \(dqSerpent Mound Model LAS Data.las\(dq,
available at
appliedimagery.com
.br
.nf
\fC
  # print LAS file info
  v.in.lidar \-p input=\(dqSerpent Mound Model LAS Data.las\(dq
  # create location with projection information of the LAS data
  v.in.lidar \-i input=\(dqSerpent Mound Model LAS Data.las\(dq location=Serpent_Mound
  # quit and restart GRASS in the newly created location \(dqSerpent_Mound\(dq
  # real import of LiDAR LAS data, without topology and without attribute table
  v.in.lidar \-tb input=\(dqSerpent Mound Model LAS Data.las\(dq output=Serpent_Mound_Model_pts
\fR
.fi
.SH SEE ALSO
\fI
r.in.lidar,
r3.in.lidar,
g.region,
v.vect.stats,
v.in.ogr
\fR
.SH REFERENCES
ASPRS LAS format
.br
LAS library
.br
LAS library C API documentation
.SH AUTHOR
Markus Metz
.br
Vaclav Petras,
NCSU GeoForAll Lab
(decimation, cats, areas, zrange)
.br
based on \fIv.in.ogr\fR by various authors
.PP
\fILast changed: $Date: 2016\-08\-27 12:53:22 +0200 (Sat, 27 Aug 2016) $\fR
.SH SOURCE CODE
.PP
Available at: v.in.lidar source code (history)
.PP
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.PP
© 2003\-2016
GRASS Development Team,
GRASS GIS 7.2.0 Reference Manual