On Aug 25, 2010, at 12:35 PM, Markus Neteler wrote:
On Wed, Aug 25, 2010 at 4:27 PM, Dwight Needels <need...@translucida.com
> wrote:
Is there a straightforward way to encode a survey description of a
parcel in
a text file that can then be imported into GRASS as a vector? The
type of
description I am talking about looks something like this (where the
numbers
are degrees/.minutes/seconds)...
"Beginning at [a defined point], thence running North 40-35-00 East
1,125.90
feet to a point, thence turning and running South 01-01-13 West
288.89 feet
to a point, thence turning and running South 58-18-45 West 179.33
feet to a
point, [...] , thence turning and running South 83-41-12 West 36.69
feet to
the point of beginning."
m.cogo comes to mind:
http://grass.osgeo.org/grass64/manuals/html64_user/m.cogo.html
for turning this into to true coordinates, then perhaps v.in.ascii.
Markus
Fantastic!
I can bring the survey description in as a series of points by piping
the output of m.cogo to v.in.ascii, as described in the manual.
However, I had some difficulty running the shell script to import as a
vector line map (I am running William Kyngesburye's 6.4RC6-3 on Mac OS
X Leopard). It fails (as does the v.in.lines script) because 'tac' is
not available on Mac OS.
I found a 2 year old defect report (Ticket #181) that discusses this
problem in some detail. As described there, I replaced the tac command
with 'tail -r', which worked. What is the status of a general fix for
v.in.mapgen, v.in.lines and v.in.garmin? If it will be awhile, it
would be nice to include the 'tail -r' tip for Mac OS users on the
m.cogo manual page. Also, a m.cogo | v.in.lines piping example would
be useful for non-Mac OS users.
One other thing that I have not been able to figure out is how to
automatically close the line vector into a polygon to create an area
for the parcel. Given the small number of vectors involved it is easy
enough to manually edit each vector to close it, add a centroid, and
convert lines to boundaries. However, is there a good way to
accomplish the closing automatically? If so, is this something that
could be added as an option in m.cogo (or perhaps a v.in.areas wrapper
script that automatically takes care of all of the steps to close and
generate areas)? Or perhaps even a general v.in.cogo script that
imports a cogo.dat formatted file with options for bringing it in as
points, a line, or an area.
Thanks, -Dwight
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