v.import: do not snap by default

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@71577 15284696-431f-4ddb-bdfa-cd5b030d7da7

scripts/v.import/v.import.html

@@ -37,12 +37,11 @@ errors.
 
 <h3>Topology cleaning</h3>
 
-When importing polygons, non-topological polygons are converted to
-topological areas. By default, a very small snapping threshold is applied
-(1e-13 map units) to avoid topological errors caused by numerical inaccuracy
-of the input data format. If the original polygons contain errors (unexpected
-overlapping areas or small gaps between polygons), the import might
-need to be repeated using a larger <em>snap</em> value.
+When importing polygons, non-topological polygons are converted to 
+topological areas. If the input polygons contain errors (unexpected 
+overlapping areas, small gaps between polygons, or warnings about being 
+unable to calculate centroids), the import might need to be repeated 
+using a <em>snap</em> value as suggested in the output messages.
 
 <!-- TODO: add hints for latlong -->
 

scripts/v.import/v.import.py

@@ -63,8 +63,8 @@
 #% key: snap
 #% type: double
 #% label: Snapping threshold for boundaries (map units)
-#% description: '-1' for no snap
-#% answer: 1e-13
+#% description: A suitable threshold is estimated during import
+#% answer: -1
 #% guisection: Output
 #%end
 #%option