.TH v.outlier 1grass "" "GRASS 6.4.2" "Grass User's Manual"
.SH NAME
\fI\fBv.outlier\fR\fR  - Removes outliers from vector point data.
.SH KEYWORDS
vector, statistics
.SH SYNOPSIS
\fBv.outlier\fR
.br
\fBv.outlier help\fR
.br
\fBv.outlier\fR [-\fBe\fR] \fBinput\fR=\fIname\fR \fBoutput\fR=\fIname\fR \fBoutlier\fR=\fIname\fR  [\fBqgis\fR=\fIname\fR]   [\fBsoe\fR=\fIfloat\fR]   [\fBson\fR=\fIfloat\fR]   [\fBlambda_i\fR=\fIfloat\fR]   [\fBthres_o\fR=\fIfloat\fR]   [--\fBoverwrite\fR]  [--\fBverbose\fR]  [--\fBquiet\fR] 
.SS Flags:
.IP "\fB-e\fR" 4m
.br
Estimate point density and distance
.br
Estimate point density and distance for the input vector points within the current region extends and quit
.IP "\fB--overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB--verbose\fR" 4m
.br
Verbose module output
.IP "\fB--quiet\fR" 4m
.br
Quiet module output
.PP
.SS Parameters:
.IP "\fBinput\fR=\fIname\fR" 4m
.br
Name of input vector map
.IP "\fBoutput\fR=\fIname\fR" 4m
.br
Name for output vector map
.IP "\fBoutlier\fR=\fIname\fR" 4m
.br
Name of output outlier vector map
.IP "\fBqgis\fR=\fIname\fR" 4m
.br
Name of vector map for visualization in QGIS
.IP "\fBsoe\fR=\fIfloat\fR" 4m
.br
Interpolation spline step value in east direction
.br
Default: \fI10\fR
.IP "\fBson\fR=\fIfloat\fR" 4m
.br
Interpolation spline step value in north direction
.br
Default: \fI10\fR
.IP "\fBlambda_i\fR=\fIfloat\fR" 4m
.br
Tykhonov regularization weight
.br
Default: \fI0.1\fR
.IP "\fBthres_o\fR=\fIfloat\fR" 4m
.br
Threshold for the outliers
.br
Default: \fI50\fR
.PP
.SH DESCRIPTION
\fIv.outlier\fR removes outliers in a 3D point cloud. By default, the outlier
identification is done by a bicubic spline interpolation of the
observation with a high regularization parameter and a low resolution
in south-north and east-west directions. Those points that differ in
an absolute value more than the given threshold from a fixed value,
reckoned from its surroundings by the interpolation, are considered as
an outlier, and hence are removed.
There is a flag to create a vector that can be visualizated by
qgis. That means that topology is build and the z coordinate is
considered as a category.
.SH EXAMPLES
.SS Basic outlier removal
\fC
.DS
.br
v.outlier input=vector_map output=vector_output outlier=vector_outlier thres_O=25
.br
.DE
\fR
In this case, a basic outlier removal is done with a threshold of 25 m.
.SS Basic outlier removal
\fC
.DS
.br
v.outlier -q input=vector_map output=vector_output outlier=vector_outlier qgis=vector_qgis
.br
.DE
\fR
Now, the outlier removal uses the default threshold and there is also
an output vector available for visualizaton in QGIS
(http://www.qgis.org).
.SH NOTES
This module is designed to work with LIDAR data, so not topology is
built but in the QGIS output.
.SH SEE ALSO
\fIv.surf.bspline\fR
.SH AUTHORS
Original version of the program in GRASS 5.4:
.br
Maria Antonia Brovelli, Massimiliano Cannata, Ulisse Longoni and Mirko Reguzzoni
.br
Updates for GRASS 6:
.br
Roberto Antolin
.PP
\fILast changed: $Date: 2011-09-27 11:02:59 +0200 (Tue, 27 Sep 2011) $\fR
.PP
Full index
.PP
© 2003-2011 GRASS Development Team