12
votes
Counting adjacent polygons using QGIS
Using the field calculator, you can use array_length( overlay_intersects( @layer,"")) to identify and count the intersecting geometries
- 43.4k
8
votes
Accepted
Creating list of adjacent polygons in QGIS
You can use SQL and join the layer to itself based on a maximum distance and where the ids are different (to prevent joining polygons to themselves).
Change mylayer to the name of your layer, and 30 ...
- 77.9k
7
votes
Accepted
How do I merge/dissolve two polygons within one shapefile in QGIS?
It's a little tricky given that the dissolve/union simply extracts separate shapefile. Here is how you could do that:
STEP 1: In the menu item go to: VIEW>TOOLBAR, and then toggle on "Advanced ...
- 510
7
votes
Creating list of adjacent polygons in QGIS
To complete the answers given so far: you can also use the field calculator to get a list of neighbours, with the expression:
array_to_string(
overlay_nearest(
layer:='polygons',
...
- 11.9k
6
votes
Determining if polygon not enclosed by other polygons
Assuming your polygons are topologically correct (no gaps, or overlaps), then a polygon A is enclosed by other polygons if its perimeter is equal to the sum of intersection length between its ...
- 13.2k
6
votes
Accepted
Make line from each polygon centroid to each adjacent polygon centroid in QGIS
Use this expression:
collect_geometries(
array_foreach(
overlay_intersects (@layer, centroid ($geometry)),
make_line (centroid($geometry), @element)
)
)
- 75k
5
votes
Dissolve (merge) polygons QGIS based on attribute values only when are adjacent
Option one: Merge features only when they belong to the same country.
The Dissolve tool allows you to select more than one attribute as the Dissolve field. Use these two fields for the Dissolve field:...
- 25.1k
5
votes
How to find neighboring polygons which share a common feature in ArcMap 10.4?
This can be done in ModelBuilder as you have asked to automate this.
Use a feature selection iterator to iterate over your regions. Output of that feeds into a select by location tool to select your ...
- 44.6k
5
votes
Accepted
Are contiguity matrix and adjacency matrix the same?
Yes.
An online comparer has this for "contiguous":
The state of being adjacent or contiguous; contiguity; as, the adjacency of lands or buildings.
I'd say "adjacent" was the ...
- 66.5k
5
votes
Accepted
Counting adjacent polygons using QGIS
The suggestion provided by @JGH is good but will only work in some instances, I'd suggest you to use nearest with an upper limit and a safe maximum distance.
In my example below I used array_length(...
- 682
4
votes
how to remove small water bodies in binary mask array that we get from ndwi values?
You can use gdal_sieve to remove small areas of noise. From the documentation:
gdal_sieve.py script removes raster polygons smaller than a provided threshold size (in pixels) and replaces them with ...
- 3,794
4
votes
Accepted
Merging polygons that share one vertex (node neighbors) using ArcGIS Desktop?
Suggestion in my comments "Convert back to integer raster, region group, to polygons, dissolve to multipart" will work for polygons derived from rasters.
However in general it's better to start with ...
- 23.3k
4
votes
Why do clipped polygon features (clipped with adjacent polygon tiles) still overlap with each other?
I can't say how to correct the topology automatically but these images should show what happens.
These are the vertices of the left side polygon (clipped1) and the location of the overlap.
These are ...
- 69.2k
4
votes
Accepted
Filtering polygons that share more than 2 vertices using QGIS
You can achieve this using a virtual layer.
It would select polygons from the layer where they intersect the source layer, then only for these, it would compute the intersection and if there is more ...
- 43.4k
3
votes
Ordering polygon neighbors in clockwise order using ArcMap
This workflow will create mid points of edges between polygons and delete outer ones called "LINKS":
arcpy.FeatureToLine_management(in_features="PGONS", out_feature_class="C:/...
- 23.3k
3
votes
Simplifying adjacent polygons on subset of vertices only
I hope that I understood your question correctly.
Let's assume there one layer "polygons" with its corresponding attribute table accordingly, see image below.
And of course there are some ...
- 34.1k
3
votes
Determining if polygon not enclosed by other polygons
I have an answer that should be logically correct but the SQL part is not complete. The idea is based on intersections of adjacent polygons. The intesections are either lines if polygons share segment(...
- 69.2k
3
votes
Identifying/exporting adjacent polygons in ArcGIS Desktop?
An approach is:
select the polygons with your agricultural data (e.g counties where wheat is only grown). You would do that with your select by attribute tool.
Then run the select by location tool ...
- 44.6k
3
votes
Accepted
Merging adjacent polygons in QGIS
You could ask the dissolve tool which you can select through the Vector tab, then Geoprocessing tools.
Then select the dissolve tool to open and input the dataset
You could also refer to QGIS ...
- 12.1k
2
votes
Accepted
Counting polygon neighbours and writing to table using PyQGIS?
The script from the linked website writes not the number of neighboring polygons but the summed up value for an attribute from the layer (e.g. the total population for all neighboring countries) to ...
- 2,351
2
votes
Accepted
Using Polygon Neighbors for boundary polygons to find boundary lengths in ArcMap?
The trick here is counting number of neighbors that share polygon edges. Workflow for that using spatial join one to many:
arcpy.Integrate_management(in_features="COUNTIES #", cluster_tolerance="0.01 ...
- 23.3k
2
votes
Simplifying adjacent polygons using PostGIS?
As of PostGIS 3.4.0, there is a dedicated function which does exactly this:
ST_CoverageSimplify(geometry winset geom, float8 tolerance, boolean simplifyBoundary = true)
ST_CoverageSimplify docs
...
- 1,713
2
votes
Identifying shared polygon boundaries in ArcGIS Desktop
To do this I would use the Polygon Neighbors tool which (with my bolding):
Creates a table with statistics based on polygon contiguity (overlaps,
coincident edges, or nodes).
- 65.4k
1
vote
ArcGIS Pro matching and dissolving neighbours
Without seeing the full dataset and understanding the topological relationships within your data we only have your isolated block of touching polygons to go by. What we don't know is the nature of ...
- 44.6k
1
vote
Why do clipped polygon features (clipped with adjacent polygon tiles) still overlap with each other?
So, your raw data in text format is shown below:
P1
MULTIPOLYGON(((
20.0857554080356 49.1905790194619,
20.0887585780746 49.1908207752517,
20.0913701395045 49.1907900830797,
20.0919317359928 49....
- 4,527
1
vote
Polygon Neighbors tool produces incorrect results
This is what tool does if you uncheck "Include both sides" option:
So if you'll decide to compute number of neighbors by counting frequency of src_OBJECTID, you'll end up with very few (...
- 23.3k
1
vote
Identifying shared polygon boundaries in ArcGIS Desktop
For example Intersect with
Polygon inputs and line output:
Then you can Select By Location to select the polygons that intersect the intersect lines.
- 77.9k
1
vote
Simplifying adjacent polygons on subset of vertices only
The job can be done with OpenJUMP but the method is generic and any software can be used. What matters is that the software must be able to create a planar graph and build polygons from closed areas ...
- 69.2k
1
vote
Simplifying adjacent polygons on subset of vertices only
Clarification - if you do not have an "id" field in your table, create it and use it to identify the right and left (upper and lower) adjacent polygons.
One of the ways to solve this ...
- 4,527
1
vote
Accepted
Checking if selected features are adjacent using OpenLayers
Using turf.js#intersect method you can find out if two features share a border.
from their docs:
Takes two polygons and finds their intersection. If they share a border, returns the border; if ...
- 201
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