[GRASSLIST:4934] Re: distance
glynn.clements at virgin.net
Mon Nov 11 15:09:53 EST 2002
J.c.m. van der Kwast wrote:
> Is it possible to fill a raster of an irregular shaped area with
> distance values perpendicular to a part of the edge of the same area, so
> that hat every cell has a distance value perpendicular and relative to a
> part of the edge?
> I've been trying some things with mapcalc but without succes. So far
> according to me, the only way to do it would be to raster the line, and
> then buffer it with mask set to that polygon. Very tedious job if areas
> are big (maybe script?). Another approach was to draw parallel lines in
> a CAD program, depicting them as heightlines in Grass and then putting
> them thru v.surf.contours or s.surf.contours. This is not working to my
> satisfaction. I'll hope you'll have some insights, if it's possible at all.
If you create a map where the inside of the polygon has value 1 while
the outside has value 0, running r.cost with a start coordinate which
is outside of the polygon will give approximately the right result.
Glynn Clements <glynn.clements at virgin.net>
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