[GRASS-user] Re: QGIS GRASS plugin shadedrelief issue

Micha Silver micha at arava.co.il
Mon Sep 20 09:43:20 EDT 2010

nunosousa84 wrote:

> Good question Micha. Well i remember i checked the vector lines after
> completing them (things like not crossing, not touching and confirming that
> all of the lines has attributes to them, in this case altitude values). Then
> i checked overlapping raster contours in relation to the vector lines to see
> if there was any deviance from the original vector lines. I cant find any
> problem with this. mmm... what could it be? Somekind of overlapping cells? 
The way you can check is with v.clean. It has an option to break line 
vector at all line crossings and create a point vector of the crossings:
v.clean <your contour line vector> out=contour_clean tool=break 

If the resulting crossings vector has any points, compare them with the 
"black spots".

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