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Questions tagged [polygon]

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.

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1 answer
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New flow direction attribute for sub-catchment layer in QGIS

I have a polygon layer in QGIS with self-created sub-catchments. I also have a DEM, a flow-direction raster and a raster with the corresponding stream network and stream order. I would like to create ...
Fabi's user avatar
  • 33
1 vote
0 answers
21 views

How to deal with concurrency when inserting polygons in a SQL table in a way that they don't intersect with each other

Problem: I have a table X, in which I am inserting polygons (ex: geometry data for a city). Before inserting them, I check if the input polygon intersects with any existing polygon in the table and ...
xorrax's user avatar
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1 vote
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QGIS - Synchronize polygons changes between layers

I'm working with two distinct SpatiaLite layers, each with specific fields (they are not duplicates of each other). While working on HABITATS_POLY, I aim to update ZONES_HUMIDES_POLY based on field ...
Giene's user avatar
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27 views

QGIS: Further subdivide sub-catchments based on DEM

I have a DEM and a vector layer with existing hydrological sub-catchments. Is there a way in QGIS to further subdivide the sub-catchments based on the DEM?
Fabi's user avatar
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1 answer
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Calculating width for non perfectly aligned polygon in ArcGIS Pro

I have a non perfectly aligned polygon feature (blue) for which I want to calculate the minimal width: Now when I run the “minimum boundary geometry”-tool in ArcGIS Pro, the area for which the width ...
Foeke Boersma's user avatar
7 votes
3 answers
598 views

Removing polygons that look like lines in QGIS

I calculated the difference between 2 massive polygon layers with the Difference tool in QGIS. I get the result I wanted...more or less. The problem is that there are a bunch of lines that appear in ...
vivjmin's user avatar
  • 111
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0 answers
13 views

How to generate the mean of each SOA polygon

I have air pollution data for each different year in shapefile format. I imported each year into QGIS and the shapefiles are in points format and then I added an Esri layer for the air pollution ...
RAWAN AHMAD ALHATTAB's user avatar
1 vote
0 answers
20 views

Calculate surface area of a geography instance using StArea() in T-SQL

In my (Azure SQL Server) database I have stored polygons in the format "MULTIPOLYGON (((longitude1 latitude1, longitude2 latitude2, etc)))". I want to calculate the total surface area of ...
user11453289's user avatar
4 votes
2 answers
162 views

Problem with ST_Difference in PostGIS

I'm testing various SQL queries to do a seemingly easy ST_Difference in PostGIS. It needs to be done in SQL as I'm testing to later use the query on quite large datasets. Original code I tried: CREATE ...
vivjmin's user avatar
  • 111
5 votes
3 answers
170 views

Segmentation of a network at branches from one complex boundary polygon

If I have the polygon defining boundaries of a river network, is there any way to directly segment the tributaries out using geospatial data analysis? To elaborate, I am looking for a workflow more ...
MathX's user avatar
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1 answer
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Get centroid xy of selected polygon feature for UTM

Building a Script Tool that will take a selected polygon feature iterating through a 1 deg x 1 deg grid feature class. The tool creates a new geodatabase with name from [GEOCELL] field of selected ...
atv5150's user avatar
  • 63
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Buffer around outer edge of polygon

I'm working in QGIS. I have a multipolygon layer and I want to create a 1.5 mile buffer around the outer edge of each polygon. The output of the Buffer tool (set to 1.5 miles) doesn't quite reach 1.5 ...
csft306's user avatar
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0 votes
1 answer
54 views

Fill holes in polygon that does not connect with surroundings

I have created a vectorization from a raster of a sea model of Denmark as suggested here https://gis.stackexchange.com/a/478370/240539 using QGIS. I get this vectorization: I wish to fill the holes in ...
Lukas Eliassen's user avatar
3 votes
2 answers
208 views

QGIS: Removing overlapping features in one layer

I have a dataset in QGIS with polygon features that partially overlap completely. I would like to delete the overlapping polygon features so that each area is only covered by one feature. The decision ...
Fabi's user avatar
  • 33
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0 answers
38 views

How to clip satellite base map into polygons [duplicate]

I'm trying to create a model to detect trees within the boundary of a country in QGIS 3.34. So far, I'm using the Google Maps Satellite base map from QuickMapServices. I created a vector layer where I ...
Bartek's user avatar
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0 answers
73 views

Convert polygons to lines that are split depending on borders being shared

I have a file containing polygons that delineate the boundaries of municipalities within a specific region. I want to convert the polygon boundaries to lines. The resulting lines should be split ...
Dimitar's user avatar
  • 11
2 votes
1 answer
77 views

Mark overlapping areas in QGIS

I have one layer in QGIS with many polygons (drawn in different colors) that partially overlap. How can I mark the areas that overlap separately (e.g. dashed)? Here is an example: The colors of the ...
leberkas-lover55's user avatar
0 votes
1 answer
36 views

How do I calculate kernel density home ranges of animals in QGIS?

I am trying to calculate the kernel density home ranges of some animal occurrences in QGIS. I found the following website with a model, how do I import it and run it in QGIS? https://plugins.qgis.org/...
MapDeath's user avatar
  • 333
3 votes
1 answer
62 views

Dissolve neighbour polygons when distance is below X meters

I like to dissolve polygons in QGIS which are separated by small gaps (streets or paths...). As shown in the picture below, the two polygons in the north should be dissolved, excluding the one in the ...
BAE_23's user avatar
  • 667
0 votes
1 answer
34 views

Inconsistent plot behaviour between geopandas/folium/leaflet and plotly

I need to plot an interactive map of German postal code regions. For this I would like to employ a plotly.express.choropleth map. For roughly ~7500 of the 8300 regions this works like a charm. ...
J Berz's user avatar
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2 votes
1 answer
35 views

I have polygon data saved as a long text string of coordinates saved as .csv. How can I add it into QGIS?

The data provided to me are saved as .csv files, and are listed in this manner: {"type":"Polygon","coordinates":[[[120.9919351,14.5451086],[120.9939584,14.545671],[120....
Mike's user avatar
  • 21
0 votes
0 answers
34 views

Computing spatial (zonal) statistics of gridded data (NetCDF file) for polygons in a shapefile (EU NUTS2 regions)

I have the shapefile of NUTS2 region, with crs:EPSG:4326 I also have a NetCDF file which is a 950*1000 cell. I want to compute mean per polygon based on the data in the NetCDF file with Python. I'm ...
Anis's user avatar
  • 1
1 vote
2 answers
56 views

QGIS - Creating a polygon from a section of a different line

I would like to create a polygon layer using a section of a different line layer. I selected the line component (orange highlight) which came from a high tide line shapefile and would like to use that ...
Lane Simkin's user avatar
-2 votes
1 answer
74 views

QGIS - trying to draw polygons [closed]

I´m complety new in this game, so unfortunately I havent figured out how I get my data into QGIS onto a map. I got my data delievered in a Excel sheet (no words need) and it looks like this. I have ...
Maverick13.1988's user avatar
0 votes
1 answer
29 views

Median value within polygon of a data layer like NDVI- iterate over multiple polygons defined in map interface

I have a script below that will calculate the median NDVI for any polygon, store it, and chart it for export, over a range of dates. The script also performs some cloud masking prior to NDVI ...
SteveV's user avatar
  • 21
0 votes
1 answer
59 views

Select point features within same polygon AND with same field value QGIS

The situation I have a point layer ("Beobachtungen") and a single part polygon layer ("Single parts"). For both layers, every feature has a unique id. As shown in the image, some ...
Hannes's user avatar
  • 129
1 vote
0 answers
34 views

QGIS 3.22.16 using a unique color for each category

I am using QGIS 3.22.16. I am trying to symbolize multiple land owners using the categorize option. However, the random selection brings similar color for different landowner. I tried to use different ...
GIS Noh's user avatar
  • 321
1 vote
1 answer
37 views

Extract polygons from TIFF file of depth model

I am trying to create a shapefile of polygons from a TIFF file using QGIS. The TIFF file represents a depth model of Denmark. I want to create the polygons based on a particular depth (-2 meters), ...
Lukas Eliassen's user avatar
2 votes
0 answers
56 views

Why are there so many slivers in my polygon shapefile?

I georeferenced a map and then traced a vector polygon shapefile over it, but when I dissolve it I am left with an enormous amount of slivers. All the vertices are snapped as far as I'm aware. What ...
MapDeath's user avatar
  • 333
3 votes
3 answers
66 views

Intersection without cutting off whole polygon using QGIS

I am trying to intersect a larger map of MSOAs with a 50km ring to create a set of MSOAs within the ring. However, I would like to keep the MSOAs whole, even if not all of it lies within the 50km ring....
user240401's user avatar
0 votes
1 answer
19 views

Calculating group area percentages in ArcGIS Pro using Summarize Within

I have a grid (vector file) in ArcGIS Pro, and I want to calculate the percentages of the area of different anthrome types in another vector file (Anthromes 12K DGG Dataverse) for each grid cell. I ...
cloudberry's user avatar
0 votes
0 answers
11 views

Multidimensional Poverty Index Subnational Geographies

I am looking to merge data from Oxford's Multidimensional Poverty Index (MPI) at a subnational level with GADM boundaries, but I'm finding only about 60% match rates. Does anyone know either the ...
Thomas Hampton's user avatar
1 vote
1 answer
129 views

Creating radial lines from center of polygon to edge in QGIS

I have a set of polygons for which I need 16 radial lines each from the centroid of the polygon to the edge (see image). So far I have only found a python script to create radial points for a circle (...
Denise's user avatar
  • 91
0 votes
0 answers
45 views

Area of intersection between two polygons: TopologyException: Input geom 0 is invalid

I am trying to compute the area of the intersection of two polygons as follows: inter = geomap_ilot.sjoin(df_final_quartiers_arrond) def f(frame): """A function to calculate ...
bravopapa's user avatar
  • 475
2 votes
2 answers
91 views

Selecting points which are not in polygons using GeoPandas

I have got two geodataframes: df1 which has got points as geometry type and has around 2.5 million rows, df2 has got polygons/multipolgyons as geometry type and has over 2.6 million rows. I want to ...
user2293224's user avatar
1 vote
1 answer
66 views

Performing a zonal statistics looping over rasters and over polygons

I have a shapefile with overlapping polygons and a set of rasters. I would like to summarize some statistics on my polygons. However, as my polygons are overlapping, to avoid issues with zonal_stats, ...
OgeiD's user avatar
  • 556
1 vote
0 answers
82 views

QGIS ellipsoidal area values changing very slightly between calculations while planimetric values stay the same

I have a number of vector shapefiles that I need to calculate the geodesic/ellipsoidal area for. These shapefiles are accessed and updated regularly, with the area recalculated each time they are ...
ecoQs's user avatar
  • 57
0 votes
0 answers
15 views

Model designer QGIS question - Function toggles

I just recently started using the model designer and I was wondering if anyone knows of a way to switch between the paths the process goes through. As in some kind of toggle that would allow us at the ...
user238820's user avatar
1 vote
1 answer
102 views

Finding rectangular polygons in a multipolygon

I'm trying to do some analysis that requires finding rectangular gardens of a certain size. At present, I only have access to a data set of property extents with buildings punched out with the ...
CitizenFish's user avatar
1 vote
1 answer
71 views

Finding shortest distance from one point to each polygon and the distance from that point of the polygon to any of the points in the polygon in QGIS

I'm trying to find the shortest distance from a point (point A uploaded as a CSV) to a polygon uploaded as a shapefile (polygon 1) and then the distance from that point of the polygon to any of the ...
QHNL's user avatar
  • 21
1 vote
0 answers
63 views

Removing the split between merged polygon in QGIS

I merged two polygons within one shapefile and then aligned all the vertices so that they were adjacent, but how do I remove the former edges that bisect the polygon so that the geometry is continuous?...
MapDeath's user avatar
  • 333
1 vote
0 answers
47 views

Converting Leaflet polygon to GeoJSON?

I have the following piece of code of my Leaflet application (Typescript): getPolygonMarker(): GeoJSON { let itemShape: any = [ wktToGeoJSON(item['contour'],) ]; const p = new ...
smartmouse's user avatar
3 votes
1 answer
111 views

Combining multiple Polygons into one MultiPolygon in QGIS

QGIS 3.34.3 has a processing function "Multipart to singleparts". But what about the other way around? What is the easiest way to create a MultiPolygon from several polygons?
christoph's user avatar
  • 5,645
3 votes
1 answer
189 views

How do I merge/dissolve two polygons within one shapefile in QGIS?

I have a shapefile composed of many polygons. I want to merge/combine/dissolve some adjacent polygons that I have selected within the shapefile into one polygon without any slivers or lines left in ...
MapDeath's user avatar
  • 333
0 votes
0 answers
50 views

Merging Points and Polygons

I'm very new to using QGIS and I'm struggling with one aspect of creating a set of polygons by land tenure. Essentially I have four sets of landowners each with parcels of land - I have converted the ...
Luca's user avatar
  • 1
2 votes
1 answer
88 views

Get the outline of badly optimized polygons (too many vertices?)

I'm trying to get the area of some flooding data. Overall, the dataset is huge and hardly to handle in QGIS. The dataset comes in several shapefiles ranging from 60 Mb to 4 Gb and include several ...
Waynenation's user avatar
0 votes
1 answer
58 views

Some polygons are loading incorrectly as terra SpatVect but not SpatialPolygonsDataFrames

I am seeing an issue with some polygon features loading incorrectly as terra SpatVectors. I cannot replicate this issue yet, but here is an example polygon as an rds on Google Drive. If I load this ....
Scott Z's user avatar
  • 141
0 votes
0 answers
37 views

Creating automatic page size from polygons

I am new to QGIS, so I will try my best to describe what I am trying to do. I have a line feature, along which I have created an array of the same sized polygons/grey squares. I am trying to create a ...
CaptainFishboy's user avatar
0 votes
1 answer
66 views

Remove internal boundaries from a polygon in QGIS

I'm currently trying to retrieve XY coordinates from the perimeter of a polygon (using MMQGIS). When I have a single continuous polygon I face no issues. However, when the polygon is a mix of land ...
Buce1's user avatar
  • 23
0 votes
1 answer
48 views

KML file polygon rendering weirdly in Google Earth

I'm trying to write KML that displays a polygon with the north point at the north pole, the south point at the south pole, and the east and west points on the equator with 15° longitude separation. I ...
SteveJonesMO's user avatar

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