Interpolation spline step value in north direction
Default: 4
lambda_g=float
Regularization weight in gradient evaluation
Default: 0.01
tgh=float
High gradient threshold for edge classification
Default: 6
tgl=float
Low gradient threshold for edge classification
Default: 3
theta_g=float
Angle range for same direction detection
Default: 0.26
lambda_r=float
Regularization weight in residual evaluation
Default: 2
DESCRIPTION
v.lidar.edgedetection is the first of three step to filter
LIDAR data. It detects the edge of each single feature over the
terrain surface of a LIDAR point surface. First of all, those points
with a high gradient value are determined. Then, it is valued the
difference between the observation of those points and a generic
interpolated surface with splines. If the difference is positive, then
the point could supposed to be inside the object, else the point could
supposed to be outside the object. The final output will be a vector
map in which points has been classified as TERRAIN, EDGE or
UNKNOWN. This output will be the input of v.lidar.growing
module.
NOTES
In this module, an external table will be created which will be
useful for the next module of the procedure of LIDAR data
filtering. In this table the interpolated height values of each point
will be recorded.
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
TERRAIN DOUBLE PULSE
OBJECT SINGLE PULSE
OBJECT DOUBLE PULSE
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
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. e 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 ?2002, pp. 7- 26