v.outlier(1)

1v.outlier(1)                  Grass User's Manual                 v.outlier(1)
2
3
4

NAME

6       v.outlier  - Removes outliers from vector point data.
7

KEYWORDS

9       vector, statistics
10

SYNOPSIS

12       v.outlier
13       v.outlier help
14       v.outlier     input=name    output=name    outlier=name     [qgis=name]
15       [soe=float]      [son=float]      [lambda_i=float]      [thres_o=float]
16       [--overwrite]  [--verbose]  [--quiet]
17
18   Flags:
19       --overwrite
20           Allow output files to overwrite existing files
21
22       --verbose
23           Verbose module output
24
25       --quiet
26           Quiet module output
27
28   Parameters:
29       input=name
30           Name of input vector map
31
32       output=name
33           Name for output vector map
34
35       outlier=name
36           Name of output outlier vector map
37
38       qgis=name
39           Name of vector map for visualization in QGIS
40
41       soe=float
42           Interpolation spline step value in east direction
43           Default: 10
44
45       son=float
46           Interpolation spline step value in north direction
47           Default: 10
48
49       lambda_i=float
50           Thychonov regularization weigth
51           Default: 0.1
52
53       thres_o=float
54           Threshold for the outliers
55           Default: 50
56

DESCRIPTION

58       v.outlier  removes  outlier points. By default, the outlier identifica‐
59       tion is done by a bicubic spline interpolation of the observation  with
60       a high regularization parameter and a low resolution in south-north and
61       east-west directions. Those points that differ  in  an  absolute  value
62       more  than  the  given  threshold from a fixed value, reckoned from its
63       surroundings by the interpolation, are considered as  an  outlier,  and
64       hence  are  removed.   There  is  a flag to create a vector that can be
65       visualizated by qgis. That means that topology is build and the z coor‐
66       dinate is considered as a category.
67

EXAMPLES

69   Basic outlier removal
70
71       v.outlier  input=vector_map output=vector_output outlier=vector_outlier
72       thres_O=25
73        In this case, a basic outlier removal is done with a threshold  of  25
74       m.
75
76   Basic outlier removal
77
78       v.outlier  -q input=vector_map output=vector_output outlier=vector_out‐
79       lier qgis=vector_qgis
80        Now, the outlier removal uses the default threshold and there is  also
81       an    output    vector    available    for    visualizaton    in   QGIS
82       (http://www.qgis.org).
83

NOTES

85       This module is designed to work with LIDAR data,  so  not  topology  is
86       built but in the QGIS output.
87

AUTHORS

92       Original version of the program in GRASS 5.4:
93       Maria  Antonia Brovelli, Massimiliano Cannata, Ulisse Longoni and Mirko
94       Reguzzoni
95       Updates for GRASS 6:
96       Roberto Antolin
97
98       Last changed: $Date: 2006-09-05 01:58:47 +0200 (Tue, 05 Sep 2006) $
99
100       Full index
101
102       © 2003-2008 GRASS Development Team
103
104
105
106GRASS 6.3.0                                                       v.outlier(1)