NAME
v.spag - Process spaghetti-digitized binary vector file.
(GRASS Vector Program)
SYNOPSIS
v.spag
v.spag help
v.spag [-i] map=name [threshold=value]
DESCRIPTION
This program will fix vector data that were not digitized
in correct GRASS vector format. It will create a node at
every line crossing, and will delete all hanging lines of
length less than the specified threshold.
OPTIONS
Flag:
- -i
- Only do identical line removal pass.
- -s
- Snap nodes.
- -p
- Prompt user for threshold value.
Parameters:
- map=name
- Name of the binary vector file to be fixed.
- threshold=value
- Node-snapping threshold value.
NOTES
The user must run
v.support
after running v.spag to correct
the topology (dig_plus) file.
v.spag generally deletes many lines from the input
vector map layer. Because deleted lines are not eliminated
from a vector data (dig) file, but are only marked
as deleted, the user will probably wish to run
v.clean
on the vector file after running v.spag to
eliminate any deleted lines from the dig file and
decrease its size.
BUGS
This program contains several known bugs. It will
sometimes get stuck in a loop in which it creates the same
line over and over again. It will occasionally create an
incorrect line. Users are strongly urged to back-up their
vector data files before running this alpha version of
v.spag.
Update Note:
1/93: For GRASS Release 4.1, the
-i flag has been added and bugs fixed. It works better than the
4.0 release.
6/00: The -s and -p flags has been added.
One reason for loop fixed, please report if you get into the loop after this date.
SEE ALSO
v.clean,
v.digit,
v.support
AUTHOR
Dave Gerdes, U.S.Army Construction Engineering
Research Laboratory