[GRASS-user] How to find intersection of two lines

[Moritz Lennert]

On 20/03/08 11:17, Jarosław Jasiewicz wrote:
> Hi I have lots of raster, thinned lines and second raster with with one 
> line. I must find all points where second line intersect with lines on 
> first raster
> it is very simple:
> 
> r.mapcalc points=if(raster_two==1&&raster_one==1,1,null())
> 
> but there is one exception:
> 
> AB
> BA
> 
> when lines intersect with 45 grades. There is intersection but without 
> common point. Naither buffor nor grow is not a solution because I need 
> exactly one point lying exactly on line from raster one
> 
> Any Ideas

Either ressample your rasters to coarser resolution to make them 
coincide, or convert to vector and use a combination of v.patch + 
v.clean (e.g. v.clean input=lines1 output=lines2 err=points tool=break)

Moritz