v.lidar.growinggrass - Online in the Cloud

PROGRAM:

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]
[--help] [--verbose] [--quiet] [--ui]

Flags:
--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]
Name of input vector map
Input vector (v.lidar.edgedetection output)

output=name [required]
Name for output vector map

first=name [required]
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

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