Our systems expect polygon shapefiles, representing a collection of non-intersecting and geometrically valid (multi)polygons. Specifically, farm fields. We often receive our representations of farms and their fields as polyline shapefiles containing the field boundary polylines, typically with some small geocoding errors like dangling ends.
Is there a reliable way to transform the polyline layer into a polygon layer, where the polygons perimeters are calculated as minimal loops around polylines in the shapefile? I understand I'll probably have to tidy up the polylines first.
I am primarily interested in solutions involving Quantum GIS or other free tools, since my company doesn't buy any of the professional packages.