importing vectors
Tim Szeliga
tim at snow.nohrsc.nws.gov
Tue Aug 10 17:08:12 EDT 1993
> I work with lat-lon coordinate files. I have been successful in importing
> both raster and site data into GRASS with the lat-lon coordinate system.
> The problem is in getting my vector files (state, country borders, rivers,...)
> into GRASS. I've looked at the output of v.out.ascii and tried mimicing
> its format but all I get is nothing in the vector binary file and
> v.in.ascii dumps <?? latvalue lonvalue> to the screen for all of my 30,000+
> points in my line segments.
>
Write a {perl,awk,c,emacs} program to shift each lat/lon pair over one column.
Leave column 1 open with a space.
While I have the lists attention:
I'm importing the USGS Lakes and Streams DLG datasets into Grass.
When done, (adding cr/lf where appropriate), there are vector
programs to run -
v.clean - remove dead lines
v.proj - convert the Albers to Lat/Lon
v.patch - merge vector sets
v.prune - thin vector lines by removing points
v.spag - rationalize haphazard digitization
v.trim - trim short lines and spurs
In what order should these be run? What are suitable values?
The original data is 1:200000, but will be used with 30-arc-sec
DEM on a fairly small scale. v.prune moves the data too much
to use for hydrologic modeling. Any thoughts?
Tim Szeliga tim at snow.nohrsc.nws.gov CURRENTLY READING - "Forty-Seventeen"
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
It's a rather pleasant experience to be alone in a bank at night.
Willie Sutton
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