NAME

       v.in.lidar  - Converts LAS LiDAR point clouds to a GRASS vector map with libLAS.

KEYWORDS

       vector, import, LIDAR

SYNOPSIS

       v.in.lidar
       v.in.lidar --help
       v.in.lidar                 [-ptoreib]                input=name                output=name
       [spatial=xmin,ymin,xmax,ymax[,xmin,ymin,xmax,ymax,...]]                    [location=name]
       [return_filter=string]    [class_filter=integer[,integer,...]]    [--overwrite]   [--help]
       [--verbose]  [--quiet]  [--ui]

   Flags:
       -p
           Print LAS file info and exit

       -t
           Do not create attribute table

       -o
           Override dataset projection (use location’s projection)

       -r
           Limit import to the current region

       -e
           Extend region extents based on new dataset

       -i
           Create the location specified by the "location" parameter and exit. Do not import  the
           vector data.

       -b
           Do not build topology

       --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:
       input=name [required]
           LAS input file
           LiDAR input files in LAS format (*.las or *.laz)

       output=name [required]
           Name for output vector map

       spatial=xmin,ymin,xmax,ymax[,xmin,ymin,xmax,ymax,...]
           Import subregion only
           Format: xmin,ymin,xmax,ymax - usually W,S,E,N

       location=name
           Name for new location to create

       return_filter=string
           Only import points of selected return type
           If not specified, all points are imported
           Options: first, last, mid

       class_filter=integer[,integer,...]
           Only import points of selected class(es)
           Input is comma separated integers. If not specified, all points are imported.

DESCRIPTION

       v.in.lidar  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.

       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.

       The  optional  spatial 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  -r  current region flag is
       identical, but uses the current region settings as the spatial bounds (see g.region).

       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 return_filter option allows selecting one of first, mid,
       or last returns.

       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 class_filter option allows selecting  one  or  more  classes,  as  numbers  (integers)
       separated by comma.

Location Creation

       v.in.lidar  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
       v.in.lidar will report an error message ("Projection of dataset does not appear  to  match
       current location") and then report the PROJ_INFO parameters of the source dataset.

       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 -o flag to override the projection
       check.

       If  the user wishes to import the data with the full projection definition, it is possible
       to have v.in.lidar 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 location 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 output name into the PERMANENT mapset.

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.

EXAMPLE

       This  example is analogous to the example used in the GRASS wiki page for importing LAS as
       vector points.

       The sample LAS data are in the file "Serpent  Mound  Model  LAS  Data.las",  available  at
       appliedimagery.com
         # print LAS file info
         v.in.lidar -p input="Serpent Mound Model LAS Data.las"
         # create location with projection information of the LAS data
         v.in.lidar -i input="Serpent Mound Model LAS Data.las" location=Serpent_Mound
         # quit and restart GRASS in the newly created location "Serpent_Mound"
         # real import of LiDAR LAS data, without topology and without attribute table
         v.in.lidar -tb input="Serpent Mound Model LAS Data.las" output=Serpent_Mound_Model_pts

REFERENCES

       ASPRS LAS format
       LAS library
       LAS library C API documentation

AUTHOR

       Markus Metz
       based on v.in.ogr

       Last changed: $Date: 2015-02-13 16:16:22 +0100 (Fri, 13 Feb 2015) $

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