I'm interested in determining the shortest distance from each point
in a table of points to the boundary of a polygon which surrounds
them, in a different layer. (These are hundreds of points
representing locations of schools in the greater Los Angeles
are and I need to know the distance from each to the coast, which
could be the boundary of the state, or of the U.S., etc.)
Ideally, the output would be the distance for each filling the values
of a new field in the table for the school locations.
Unfortunately, I haven't ever messed with MapBasic. Is this
something that would even be possible in MapBasic? There are a
couple of .mbx programs available from the archive site that measure
distance from a point to an object in another layer, although I'm not
sure that they're really built for something like this. In any case,
they allow determination of distance from only a single selected
point rather than batch processing.
At least one of these programs seems to try to work, as far as I can
see, by drawing a circle of x radius around the point, then
increasing the radius by a given increment, and continuing to
increase the radius until the circle becomes tangent to a line or a
polygon boundary. The radius is the distance to the point of
tangency. There are issues regarding whether the point is within or
outside the polygon, I believe.
Any suggestions?
thanks,
Mark
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Mark Thomas / Public Documents & Maps / Perkins Library
Duke University / Durham, NC 27708-0177
[EMAIL PROTECTED] / voice: 919-660-5853 / FAX: 919-684-2855
The train ...
traditional, yet environmentally sound. --Lisa Simpson
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