QGIS – Remove Unknown Shape from Polygon Shapefile

geometrymultipartoverlapping-featurespolygonqgis

I have a shapefile of the region of districts. When I zoomed in, I found a region under the district that shouldn't be here. I want to remove it and when I go down in toggle editing, delete part it removes the whole district.

Is it possible to remove only two small regions (shown in the figure) from the whole district? When I try to find its identified features they have nothing in it, just overlay shape that I want to remove. Is there any way to get get rid of these 2 shapes? I am doing this analysis in QGIS.

Update 1st:

Best Answer

Start editing
Select the part
Delete part
Draw a polygon on top of the hole
Select and merge

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Your shapefile contains a multipart single feature as mentioned by @HDunn. In order to delete separate polygons, you will need to convert this to singleparts by using the Multipart to Singleparts tool:

Vector > Geometry Tools > Multipart to Singleparts.

I ran this and saved the output as "Free space v2.shp". Now you can edit and delete those pesky polygons!

I noticed there's quite a few of those dangles in your layer. A good method may be to use GRASS's v.clean tool with the rmdangle option to remove them automatically. You can access this from:

Processing Toolbox > GRASS commands > Vector (v.) > v.clean*

I used the following parameters (note the fairly high threshold):

Before being cleaned:

After being cleaned:

If there are any more polygons you don't want, you can remove them manually as there should be a lot less of them now.

QGIS 3 Polygon Borders – Showing Only Outer Boundaries of Polygons

As an alternative approach using the "Geometry Generator" via RMC > Symbology > Symbol layer type: Geometry Generator. Keep in mind that this approach depends on the capabilities of your PC.

In the working window insert the following expression

buffer(
    collect(
        $geometry,
        group_by:="REGION_UN"
    ),
0)

Here the aggregation was done using the field "REGION_UN", however it can be any other.

So, there result will look like:

Keep in mind that in our world there are countries with some enclaves, overseas regions and territories, and other interesting areas. So, the usage of "Multipart to singleparts" can be also useful.

Additionally you can also simply duplicate the original layer and then getting rid of the country-boundaries within the regions.

References:

Styling polygon layer as dissolved with QGIS Geometry generator?

Best Answer

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[GIS] Deleting lines in QGIS

QGIS 3 Polygon Borders – Showing Only Outer Boundaries of Polygons

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