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

[Micha Silver]

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 
err=crossings

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