NAME
v.to.sites - Converts point data in a binary
GRASS vector map layer into a GRASS site_lists
file.
(GRASS Vector Program)
SYNOPSIS
v.to.sites
v.to.sites help
v.to.sites [-acCid] input=name
output=name
[dmax=value]
DESCRIPTION
The v.to.sites program extracts data from a GRASS vector map layer
and stores output in a new GRASS site_lists file.
If -a flag is selected, v.to.sites extracts all vertices from
a vector file, if not selected, it extracts site (point) features only,
ignoring lines and areas.
If -i flag is selected then, for each line, if the distance between
any two vertices on this line is greater that dmax, additional
points are added to keep the distance withing dmax range.
The resulting sites map layer can be used with such programs as
d.sites.
The user can run the program non-interactively by
specifying the names of an existing vector input map
layer and a new site list file to be output on the
command line. The program will be run interactively if the
user types v.to.sites without arguments on the
command line. In this case, the user will be prompted to
enter parameter values through the standard user interface
described in the manual entry for
parser.
OPTIONS:
Flags:
- -a
- Outputs all vertices (instead of site data only) from
vector file to site file
- -c
- The Category NUMERIC data is used instead of attribute as a
site description
- -C
- The Category TEXT data is used instead of attribute as a
site description
- -i
- Additional sites are added between each 2 points on a
line if the distance between them is greater than specified
dmax. (valid only when -a is used)
- -d
- Write attribute as double instead of cat.
If any of the sites have been labeled in
v.digit,
then the resultant site list will contain category
information (or attribute in case -a was used but
-c was not). If none of the sites are labeled, a
binary (0/1) site list file will be produced.
Parameters:
- input=name
- Name of an existing binary vector map layer from which
site data are to be extracted.
- output=name
- Name to be assigned to the resultant site_lists file.
- dmax=value
- Maximum distance between points (valid only when
-a and -i are used)
NOTES
Vector lines must be labeled.
If the flag -i is selected, a spline function is used to generate
additional points along the line. To avoid the generating of lots of points
along contours, dmax= should be really large so that v.to.sites
does not add any addtional sites to the data. On the other hand, if
additional sites data are desired, dmax= should be smaller than the
distances between existing data points.
SEE ALSO
d.sites,
v.digit
and
parser
AUTHOR
Dave Gerdes,
Irina Kosinovsky,
U.S.Army Construction Engineering
Research Laboratory
Last changed: $Date$