v.outlier(1)

1v.outlier(1)                  Grass User's Manual                 v.outlier(1)
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NAME

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

9       vector, statistics
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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]
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18   Flags:
19       --overwrite
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21   Parameters:
22       input=name
23           Name of input vector map
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25       output=name
26           Name for output vector map
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28       outlier=name
29           Name of output outlier vector map
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31       qgis=name
32           Name of vector map for visualization in qgis
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34       soe=float
35           Interpolation spline step value in east direction Default: 10
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37       son=float
38           Interpolation spline step value in north direction Default: 10
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40       lambda_i=float
41           Thychonov regularization weigth Default: 0.1
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43       thres_o=float
44           Threshold for the outliers Default: 50
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DESCRIPTION

47       v.outlier  removes  outlier points. By default, the outlier identifica‐
48       tion is done by a bicubic spline interpolation of the observation  with
49       a high regularization parameter and a low resolution in south-north and
50       east-west directions. Those points that differ  in  an  absolute  value
51       more  than  the  given  threshold from a fixed value, reckoned from its
52       surroundings by the interpolation, are considered as  an  outlier,  and
53       hence  are  removed.   There  is  a flag to create a vector that can be
54       visualizated by qgis. That means that topology is build and the z coor‐
55       dinate is considered as a category.
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EXAMPLES

58   Basic outlier removal
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60       v.outlier  input=vector_map output=vector_output outlier=vector_outlier
61       thres_O=25
62        In this case, a basic outlier removal is done with a threshold  of  25
63       m.
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65   Basic outlier removal
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67       v.outlier  -q input=vector_map output=vector_output outlier=vector_out‐
68       lier qgis=vector_qgis
69        Now, the outlier removal uses the default threshold and there is  also
70       an    output    vector    available    for    visualizaton    in   QGIS
71       (http://www.qgis.org).
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NOTES

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

81       Original version of the program in GRASS 5.4:
82       Maria  Antonia Brovelli, Massimiliano Cannata, Ulisse Longoni and Mirko
83       Reguzzoni
84       Updates for GRASS 6:
85       Roberto Antolin
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87       Last changed: $Date: 2007/04/16 21:36:04 $
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89       Full index
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93GRASS 6.2.2                                                       v.outlier(1)