xenial (1) v.in.lidar.1grass.gz

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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