[Qgis-user] Snapping options logic

[Gerardo Jimenez]

Hi the logic behind it is to create an overlap that covers your common border. This overlap must include the "initial" and "ending" node of the common border. If you do not do so you will receive the error message.

look at the pictures at the end of this thread, and notice the way the overlaps are digitized.

http://forum.qgis.org/viewtopic.php?f=2&t=9351&sid=a5887bde35ba046089071e671b354d7f

hope it helps

Gerardo Jiménez Delgado
Instituto de Investigaciones Antropológicas
Universidad Nacional Autónoma de México
Ciudad Universitaria s/n
Coyoacan 04510
Mexico City
Mexico

56 22 95 16

Date: Sat, 22 Oct 2011 13:04:30 +0100
From: gerhardus.geldenhuis at gmail.com
To: qgis-user at lists.osgeo.org
Subject: [Qgis-user] Snapping options logic

HiI am having a bit of trouble understanding the logic behind when I get an error message or not when I set snapping options.
I have taken the following steps:Create New Raster Layer
Create new Shapefile layer 01 (Polygon)Set snapping options for Shapefile to:Mode: to vertexTolerance:15Units: pixelsAvoid Int: Checked

Draw some vectors and get intersections working. ( very cool feature ! )
Create new Shapefile layer 02 (Polygon)toggle edit mode for layer 01select new Shapefile layer and toggle edit mode
draw a triangle
Now I get an error message:The feature could not be added because removing the polygon intersections would change the geometry type.
So I thought it might have to do with the snapping settings so I set the snapping settings for layer02 the be the same as layer01.

Draw triangle still get the same error.
Uncheck the Avoid Int checkbox for layer01
Draw Triangle, no error message.
I don't understand why that would cause the error message to go away. Is avoid intersections not supposed to be limited to a specific layer?

Regards
-- 
Gerhardus Geldenhuis



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