Provided by: grass-doc_6.4.3-3_all
v.outlier - Removes outliers from vector point data.
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
v.outlier 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.
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).
This module is designed to work with LIDAR data, so not topology is built but in the QGIS output.
Original version of the program in GRASS 5.4: Maria Antonia Brovelli, Massimiliano Cannata, Ulisse Longoni and Mirko Reguzzoni Updates for GRASS 6: Roberto Antolin Last changed: $Date: 2011-09-27 02:02:59 -0700 (Tue, 27 Sep 2011) $ Full index © 2003-2013 GRASS Development Team