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Geographic Information Systems

Questions tagged [polygon]

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On a map, a closed shape defined by a connected sequence of x,y coordinate pairs, where the first and last coordinate pair are the same and all other pairs are unique.

850 questions
Newest Active Bountied Unanswered
129 votes
8 answers
401k views

How do I calculate areas of an area shapefile in square meters (m²) or in acres (ha)? I didn't find that functionality in the Vector Tools.
desputin's user avatar
  • 2,381
27 votes
6 answers
29k views

I was wondering if there is a way to create center lines from polygons in QGIS? I have a polygon layer, but ideally need the centerlines as a separate file.
Alan Carr's user avatar
  • 2,469
60 votes
11 answers
71k views

I have a set of polygons representing administrative districts. The districts were digitized by hand, and there are small spaces (slivers) between polygons where the polygons should be touching. How ...
zoo's user avatar
  • 711
26 votes
6 answers
58k views

Is there an option in QGIS to fill holes in polygons automatically by setting parameters e.g. maximum area, distance between borderlines? I want to delete/fill holes that a very "thin"/small....
J-Man's user avatar
  • 269
50 votes
5 answers
104k views

Is it possible to smooth or generalize a polygon in QGIS, perhaps by using a plugin like the Generalizer Plugin for lines? I could convert my polygons to lines, smooth them and convert them back to ...
MartinMap's user avatar
  • 8,334
38 votes
4 answers
13k views

I have a PostGIS table of polygons where some intersect with one another. This is what I'm trying to do: For a given polygon selected by id, give me all of the polygons that intersect. Basically, ...
atogle's user avatar
  • 1,762
14 votes
2 answers
61k views

Using QGIS, if I load a polygon layer and make a new column, how do I fill that column with the area of each polygon and another column with the length of the perimeter of each polygon?
HealthMaps's user avatar
  • 1,035
10 votes
2 answers
10k views

I have two polygon layers, 'model' and 'ntem', whose features overlap and intersect one another. I would like to calculate the proportion of the area of the 'model' polygons which fit within each '...
Gonja's user avatar
  • 497
10 votes
4 answers
8k views

I have a shapefile with 3800 polygons representing the smallest administrative areas in Ireland. Many of these, in rural areas, have tiny populations, under 100 people. In urban areas, all would have ...
astaines's user avatar
  • 249
22 votes
5 answers
21k views

I am trying to find ways to quantitatively describe the shapes of various polygons. For my project, these polygons represent lakes, rivers, lagoons, and parks. So they can be almost any shape. One ...
user25201's user avatar
  • 381
20 votes
7 answers
27k views

There is a Plugin in QGIS 2.18 called "Polygon Divider" which divides an irregular polygon into smaller equal-area polygons of a specified/custom-sized but in QGIS 3.x version there is no &...
Kapildev adhikari's user avatar
  • 343
50 votes
11 answers
101k views

I'm creating a fictive map and so I need to create lots of points, lines and for sure polygons. Later on I export my data as geojson. But before that I aways have to go and give every element an ...
kwoxer's user avatar
  • 997
16 votes
4 answers
47k views

I have a polygon, imported from a shapefile in QGIS. I would like transform it to a linestring instead so I can save it as a GPX file later. How can I transform a polygon to a linestring in QGIS?
Jonas's user avatar
  • 2,231
15 votes
4 answers
3k views

I have a polygon layer and want to use a Virtual Layer that creates points from the vertices of the polygon layer. The question is how to write a query that does this? I am aware of the tool "...
Babel's user avatar
  • 81.1k
11 votes
3 answers
6k views

I have large single layers with many features overlapping. Simplified example with 50% transparency: Where the features overlap I want the attributes added together. I manually created the output I ...
Rx_'s user avatar
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