[GRASS-user] Converting polygons to lines

[Maciej Sieczka]

Maris Nartiss wrote:

> I just some vector data (shapefile) from someone who does not
> understand a lot from GIS. There are digitized contours as polygons
> and they height is assigned as attribute. As those polygons are
> digitized in correct order (bottom->top), data looks good for printout
> in i.e. QGIS. Polygons do not overlap (almost), they have common
> boundaries.
> 
> Is there any way how to get DEM from such data?
> 
> Any other ideas how to convert those polys to lines and not to lose
> height information?

I guess v.to.db option=sides should let you assign the attributes of
polygons to it's boundaries. If that works, you can v.extract the
boundaries next, transform them into lines (v.type) and interpolate DEM
from them with your fave module.

Maciek