NAME

       v.lidar.growing   -  Building  contour  determination  and  Region  Growing  algorithm for
       determining the building inside

KEYWORDS

       vector, LIDAR

SYNOPSIS

       v.lidar.growing
       v.lidar.growing help
       v.lidar.growing input=name output=name first=name  [tj=float]   [td=float]   [--overwrite]
       [--verbose]  [--quiet]

   Flags:
       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name
           Input vector (v.lidar.edgedetection output

       output=name
           Name for output vector map

       first=name
           Name of the first pulse vector map

       tj=float
           Threshold for cell object frequency in region growing
           Default: 0.2

       td=float
           Threshold for double pulse in region growing
           Default: 0.6

DESCRIPTION

       v.lidar.growing  is  the  second  of three steps to filter LiDAR data.  The filter aims to
       recognize and extract attached and detached object  (such  as  buildings,  bridges,  power
       lines,  trees, etc.) in order to create a Digital Terrain Model.
       The  modules  identifies  which  is  the  internal  area  of every object on a LiDAR point
       surface. The classification categories from v.lidar.edgedetection are now rasterized.  For
       each  cell,  it  is  evaluated  if  it  (the  cell)  contains  a point with double impulse
       (difference between the first and last pulse greater than  a  given  threshold).  Starting
       from  cells classified as OBJECT and with only one pulse all linked cells are selected and
       a convex hull algorithm is applied to them. Simultaneously, the mean of the  corresponding
       heights  (mean edge height) are computed.  Points inside the convex hull are classified as
       OBJECT if their height is greater than or equal  to  the  previously  mean  computed  edge
       height. This last step is done only in case of high planimetric resolution.

NOTES

       The  input  data  should  be  the  output  result  of  the  v.lidar.edgedetection, module.
       Otherwise,  it  goes  to  error!  The  output  of  this  module  will  be  the  input   of
       v.lidar.correction module. The output will be a vector map which points are pre-classified
       as:
       TERRAIN SINGLE PULSE (cat = 1, layer = 2)
       TERRAIN DOUBLE PULSE (cat = 2, layer = 2)
       OBJECT SINGLE PULSE (cat = 3, layer = 2)
       OBJECT DOUBLE PULSE (cat = 4, layer = 2)
       The  final  result  of  the  whole  procedure   (v.lidar.edgedetection,   v.lidar.growing,
       v.lidar.correction) will be a point classification in the same categories as above.

EXAMPLES

   Basic region growing procedure

       v.lidar.growing input=edge output=growing first=firstpulse

SEE ALSO

        v.lidar.edgedetection, v.lidar.correction, v.surf.bspline

AUTHOR

       Original version of program in GRASS 5.4:
       Maria Antonia Brovelli, Massimiliano Cannata, Ulisse Longoni and Mirko Reguzzoni

       Update for GRASS 6.X:
       Roberto Antolin and Gonzalo Moreno

REFERENCES

       Antolin,  R.  et  al.,  2006. Digital terrain models determination by LiDAR technology: Po
       basin experimentation. Bolletino di Geodesia e Scienze Affini, anno LXV, n. 2, pp. 69-89.

       Brovelli M. A., Cannata M., Longoni U.M., 2004. LIDAR Data Filtering and DTM Interpolation
       Within GRASS, Transactions in GIS, April 2004,  vol. 8, iss. 2, pp. 155-174(20), Blackwell
       Publishing Ltd.

       Brovelli M. A., Cannata M., 2004. Digital Terrain model reconstruction in urban areas from
       airborne  laser  scanning  data:  the  method  and an  example for Pavia (Northern Italy).
       Computers and Geosciences 30 (2004) pp.325-331

       Brovelli M. A. and Longoni U.M., 2003. Software per il filtraggio di dati  LIDAR,  Rivista
       dell?Agenzia del Territorio, n. 3-2003, pp. 11-22 (ISSN 1593-2192).

       Brovelli  M.  A.,  Cannata M. and Longoni U.M., 2002. DTM LIDAR in area urbana, Bollettino
       SIFET N.2, pp. 7-26.

       Performances of the filter can be seen in the ISPRS WG III/3 Comparison of Filters  report
       by Sithole, G. and Vosselman, G., 2003.

       Last changed: $Date: 2012-09-06 01:21:33 -0700 (Thu, 06 Sep 2012) $

       Full index

       © 2003-2013 GRASS Development Team