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Any body have ideas on how to delete a poly inside a poly? A tool, a method, a tip? If I click on the inside poly it also selects the outer poly. This is with QGIS.
Any ideas?
Any ideas?
-
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Way to delete a polygon inside a polygon?
- Thread starter Clutch Cargo
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Polys (AFAIK) don't contain other polys. A Poly can contain a hole, the hole being a child of a parent poly and you should be able to "unidentify" the hole (child) to a poly (parent).
Without wearing out my fingers trying to explain, the thought of there being a poly inside a poly leaves the question of which poly is handled in what manner...
Not familiar with QGIS, so not able to work out how that program handles things.
Without wearing out my fingers trying to explain, the thought of there being a poly inside a poly leaves the question of which poly is handled in what manner...
Not familiar with QGIS, so not able to work out how that program handles things.
Hello:
I have not used QGIS as I utilize other freeware and payware GIS utilities; but perhaps these links might help ?
https://www.google.com/#q=qgis remove polygon holes
FYI:
"fTools is now automatically installed and enabled in new versions of QGIS, and as with all plugins, it can be disabled and enabled using the Plugin Manager (See Section Loading a QGIS Core Plugin). When enabled, the fTools 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."
Of particular note is that the "FTools" utility set when utilized via QGIS, has "Geometry tools" ...including "Check Geometry", which can check polygons for intersections, closed-holes, and fix node ordering.
Also, there is reportedly a "GRASS" plugin which works inside QGIS during import of vector data which may "clean" up holes according to a user-configured minimum size for areas to be imported, and a snapping distance within which nearby boundaries are snapped together.
Resulting data sets can then be exported to 1 or more intermediate work output file(s):
"Once you are done you can export the GRASS vector in another format (ex: shapefile) by using the “save as…” QGIS function or the v.out.ogr GRASS module."
http://faunaliagis.wordpress.com/20...n-fixing-invalid-geometries-with-quantum-gis/
BTW: I'm not sure if Arno has yet implemented such functions within ScenProc during vector data import ?
If not, possibly there might be a way to save Arno the perhaps less 'FS-specific', un-necessary extra work of creating a native GUI and/or proprietary workflow in ScenProc, by initially generating a script or batch routine for ScenProc end users to utilize with QGIS / GRASS 'externally' to process specified vector source data file sets for a particular project ...before 'final' import and generation of output scenery files via ScenProc?
PS: Additionally, there is now another tool available:
"In QGIS 2.x you can now clean your vector geometries using a tool (for the Proxessing toolbox) that make use of the LWGEOM library, the one used by the PostGIS ST_MakeValid tool."
"In QGIS follow this steps:
*) install the lwgeom library with the osgeo4w installer
*) install the "Processing LWGEOM Provider" plugin
*) configure the Processing toolbox with the path to the LWGEOM library
NOTE: download "LWGEOM Provider" plugin via QGIS faunalia_processinglwgeomprovider · GitHub at:
https://github.com/faunalia/processinglwgeomprovider
Another advantageous feature of LWGEOM Provider is its preservation of all three X,Y,Z (Lon-Lat-Alt) data fields:
"This function supports 3d and will not drop the z-index."
"In polygon vector layers it is not unusual to find overlapped areas and gaps, especially if they were digitized without using the snapping or other editing tools that allow to avoid such errors.
If this kind of errors are not too big they can all be easily removed using the QGIS Processing toolbox, specifically using one of the GRASS modules and "snapping" import option. In the screencast a snapping tolerance of 1 meter is used, this will quickly remove all the overlapped areas (and close the gaps) that have a width of less than 1m."
NOTE: There are numerous other QGIS "plugins" available here:
http://plugins.qgis.org/plugins/?sort=author&per_page=180&dir=asc
[EDITED]
Another option: "The OSGeo4W package installs GDAL, OGR, QGIS, and some more things to your computer. It has it's own shell for command-line operation that is quite handy. It automates the install using the internet to download the separate programs."
http://www.fsdeveloper.com/forum/threads/osgeo4w.213311/
[END_EDIT]
Hope this might prove helpful !
GaryGB
I have not used QGIS as I utilize other freeware and payware GIS utilities; but perhaps these links might help ?
https://www.google.com/#q=qgis remove polygon holes
FYI:
"fTools is now automatically installed and enabled in new versions of QGIS, and as with all plugins, it can be disabled and enabled using the Plugin Manager (See Section Loading a QGIS Core Plugin). When enabled, the fTools 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."
Of particular note is that the "FTools" utility set when utilized via QGIS, has "Geometry tools" ...including "Check Geometry", which can check polygons for intersections, closed-holes, and fix node ordering.
Also, there is reportedly a "GRASS" plugin which works inside QGIS during import of vector data which may "clean" up holes according to a user-configured minimum size for areas to be imported, and a snapping distance within which nearby boundaries are snapped together.
Resulting data sets can then be exported to 1 or more intermediate work output file(s):
"Once you are done you can export the GRASS vector in another format (ex: shapefile) by using the “save as…” QGIS function or the v.out.ogr GRASS module."
http://faunaliagis.wordpress.com/20...n-fixing-invalid-geometries-with-quantum-gis/
BTW: I'm not sure if Arno has yet implemented such functions within ScenProc during vector data import ?
If not, possibly there might be a way to save Arno the perhaps less 'FS-specific', un-necessary extra work of creating a native GUI and/or proprietary workflow in ScenProc, by initially generating a script or batch routine for ScenProc end users to utilize with QGIS / GRASS 'externally' to process specified vector source data file sets for a particular project ...before 'final' import and generation of output scenery files via ScenProc?
PS: Additionally, there is now another tool available:
"In QGIS 2.x you can now clean your vector geometries using a tool (for the Proxessing toolbox) that make use of the LWGEOM library, the one used by the PostGIS ST_MakeValid tool."
"In QGIS follow this steps:
*) install the lwgeom library with the osgeo4w installer
*) install the "Processing LWGEOM Provider" plugin
*) configure the Processing toolbox with the path to the LWGEOM library
NOTE: download "LWGEOM Provider" plugin via QGIS faunalia_processinglwgeomprovider · GitHub at:
https://github.com/faunalia/processinglwgeomprovider
Another advantageous feature of LWGEOM Provider is its preservation of all three X,Y,Z (Lon-Lat-Alt) data fields:
"This function supports 3d and will not drop the z-index."
Code:
http://www.youtube.com/watch?v=BqJbVh_OqCE"In polygon vector layers it is not unusual to find overlapped areas and gaps, especially if they were digitized without using the snapping or other editing tools that allow to avoid such errors.
If this kind of errors are not too big they can all be easily removed using the QGIS Processing toolbox, specifically using one of the GRASS modules and "snapping" import option. In the screencast a snapping tolerance of 1 meter is used, this will quickly remove all the overlapped areas (and close the gaps) that have a width of less than 1m."
Code:
http://www.youtube.com/watch?v=t1ChPvsC4bUNOTE: There are numerous other QGIS "plugins" available here:
http://plugins.qgis.org/plugins/?sort=author&per_page=180&dir=asc
[EDITED]
Another option: "The OSGeo4W package installs GDAL, OGR, QGIS, and some more things to your computer. It has it's own shell for command-line operation that is quite handy. It automates the install using the internet to download the separate programs."
http://www.fsdeveloper.com/forum/threads/osgeo4w.213311/
[END_EDIT]
Hope this might prove helpful !
GaryGB
Last edited:
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WoW! Thank you for such a superb reply Gary. I will read up on it tonight when I get home from work. Yes, Nonew message, I do have polys inside polys or it might be I have one poly on top of another poly. Need to investigate further, but lot's of good stuff to read up on here.