v.lidar.correction(1grass) | Grass User's Manual | v.lidar.correction(1grass) |
v.lidar.correction - Corrects the v.lidar.growing output. It is the last of the three algorithms for LIDAR filtering.
vector, LIDAR
v.lidar.correction
v.lidar.correction --help
v.lidar.correction [-e] input=name
output=name terrain=name
[ew_step=float] [ns_step=float]
[lambda_c=float] [tch=float]
[tcl=float] [--overwrite] [--help]
[--verbose] [--quiet] [--ui]
v.lidar.correction is the last 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 module, which could be iterated several times, makes a comparison between
the LiDAR observations and a bilinear spline interpolation with a Tychonov
regularization parameter performed on the TERRAIN SINGLE PULSE points only.
The gradient is minimized by the regularization parameter. Analysis of the
residuals between the observations and the interpolated values results in
four cases (the next classification is referred to that of the
v.lidar.growing output vector):
a) Points classified as TERRAIN differing more than a threshold value
are interpreted and reclassified as OBJECT, for both single and double pulse
points.
b) Points classified as OBJECT and closed enough to the interpolated
surface are interpreted and reclassified as TERRAIN, for both single and
double pulse points.
The length (in mapping units) of each spline step is defined by ew_step for the east-west direction and ns_step for the north-south direction.
The input should be the output of v.lidar.growing module or
the output of this v.lidar.correction itself. That means, this module
could be applied more times (although, two are usually enough) for a better
filter solution. The outputs are a vector map with a final point
classification as as TERRAIN SINGLE PULSE, TERRAIN DOUBLE PULSE, OBJECT
SINGLE PULSE or OBJECT DOUBLE PULSE; and an vector map with only the points
classified as TERRAIN SINGLE PULSE or TERRAIN DOUBLE PULSE. The final result
of the whole procedure (v.lidar.edgedetection,
v.lidar.growing, v.lidar.correction) will be a point
classification in four categories:
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)
v.lidar.correction input=growing output=correction out_terrain=only_terrain
v.lidar.correction input=correction output=correction_bis terrain=only_terrain_bis
v.lidar.edgedetection, v.lidar.growing, v.surf.bspline, v.surf.rst, v.in.lidar, v.in.ascii
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
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: 2017-07-24 23:59:39 +0200 (Mon, 24 Jul 2017) $
Available at: v.lidar.correction source code (history)
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