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# v.outlier.1grass

Langue: en

Autres versions - même langue

Version: 331533 (ubuntu - 24/10/10)

Section: 1 (Commandes utilisateur)

## NAME

v.outlier - Removes outliers from vector point data.

## KEYWORDS

vector, statistics

## SYNOPSIS

v.outlier
v.outlier help
v.outlier [-e] input=name output=name outlier=name [qgis=name] [soe=float] [son=float] [lambda_i=float] [thres_o=float] [--overwrite] [--verbose] [--quiet]

### Flags:

-e

Estimate point density and distance
Estimate point density and distance for the input vector points within the current region extends and quit
--overwrite

Allow output files to overwrite existing files
--verbose

Verbose module output
--quiet

Quiet module output

### Parameters:

input=name

Name of input vector map
output=name

Name for output vector map
outlier=name

Name of output outlier vector map
qgis=name

Name of vector map for visualization in QGIS
soe=float

Interpolation spline step value in east direction
Default: 10
son=float

Interpolation spline step value in north direction
Default: 10
lambda_i=float

Tykhonov regularization weight
Default: 0.1
thres_o=float

Threshold for the outliers
Default: 50

## DESCRIPTION

v.outlier removes outlier points. 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.

## EXAMPLES

### Basic outlier removal

v.outlier input=vector_map output=vector_output outlier=vector_outlier thres_O=25
In this case, a basic outlier removal is done with a threshold of 25 m.

### Basic outlier removal

v.outlier -q input=vector_map output=vector_output outlier=vector_outlier qgis=vector_qgis
Now, the outlier removal uses the default threshold and there is also an output vector available for visualizaton in QGIS (http://www.qgis.org).

## NOTES

This module is designed to work with LIDAR data, so not topology is built but in the QGIS output.

v.surf.bspline

## AUTHORS

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