[GRASS-user] Converting polygons to lines

GRASS GRASS user
,
1

Hi folks,

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?

Any hints beside famous "You have to digitize again"?

Thanks,
Maris.

2

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