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Why is the Union function not working in QGIS?
It seems that the bug may be more related to running multiple iterations of the union function in QGIS without addressing topological errors that are not immediately apparent (i.e., no errors get reported).
Is there an option to ignore null geometries in QGIS?
In QGIS 2.18, when I used the Vector > Geoprocessing Tools > Intersection tool, I was able to check an option which said “Ignore NULL geometries [optional]”. Now I’ve downloaded QGIS 3.2 and that option no longer exists.
Is it normal to run grass tools in QGIS?
@technoautotroph that is “normal”: GRASS is a fullly topological GIS. When we run GRASS tools in QGIS the inputs are (on the fly) translated to simple features to a fully topological ones, this means that even by default a lot of cleaning is done, then after the geoprocessing operation the result is spit out again in simple features.
What does the processing plugin do in QGIS?
When enabled, the Processing plugin adds a Vector menu to QGIS, providing functions ranging from Analysis and Research Tools to Geometry and Geoprocessing Tools, as well as several useful Data Management Tools. See QGIS processing framework for more information about the processing framework.
How can I create a Union of layers?
I’ve tried multiple times to create a union of layers and get: “GEOS geoprocessing error: difference failed” The data is available here: https://drive.google.com/file/d/15V8DMMz9e09JXkuNONt31CWLG26TbzfX/view?usp=sharing
Why is make valid not working in QGIS?
Related to #29400 (but does not fix it) just running “make valid” may not help with the topological error caused by numerical precision issues. As mentioned in #30114, one needs to do a combination of snapping with “make valid”: We have reliable processing algs for steps 1,2,4, but for step 3 we don’t have a good one.
Why was issue # 29400 closed on QGIS?
@technoautotroph it says it clearly, was closed in favor of https://issues.qgis.org/issues/17131 that was closed because the qgis native geoprocessing tools have been in general rewritten/improved.
Related to qgis#29400 (but does not fix it) I should have caught the missing .prj files – sorry I didn’t see this. It’s been updated. @technoautotroph your data has some (a lot) of nasty geometry errors and a bunch of zero area polygons.
Where to save the line intersection layer in QGIS?
One layer containing feature (s) to be combined. Second layer containing the feature (s) to be combined. Where to save the intersection layer. Can be saved to file, a temporary file or a memory layer. Where to save the line intersection layer.
How does the vector overlay-QGIS algorithm work?
This algorithm uses spatial indexes on the providers, prepared geometries and apply an intersection operation if the geometry isn’t wholly contained by the mask geometry. The layer containing the features to be clipped. The layer containing the features that are used to clip the features in the input layer.