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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Spatial clustering with areas in QGIS or Python

I am working in QGIS with shapefiles containing several polygon features with various areas. I would like to cluster neighbor polygons in a way that results in clusters of approximately the same total ...
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Invalid GIS data provided to function st_polygonfromtext in MySQL

I have a table in MySQL with geometry data in one of the columns. The datatype is text and I need to save it as Polygon. I have tried a few solutions, but keep running into the error Invalid GIS data ...
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Creating polygon mask in QGIS

In QGIS 3.22.5, is there possible to use polygons for the masking layer? I want to use numerous little polygons to mask lines (only layer which consists of lines). In ArcGIS that works just by ...
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Selecting the maximum value from series of polygons that intersect with line in QGIS

Is there a way to select the cell (single) with the maximum value in a polygon layer using the intersection of a line? The first image is the grid (polygon) layer with the attribute field "VALUE&...
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  • 105
2 votes
1 answer
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Polygon boundary from shapefiles not in latitude/longitude format

I just downloaded the shapefiles for the County boundaries in Minnesota from here. Now I am expecting the boundaries of the Polygons/MultiPolygons to consist of latitude and longitudes (according to ...
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2 votes
1 answer
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Calculating cumulative sum of area values in attribute table by graphics in QGIS

In QGIS I have a set of polygons divided into plots, each polygon has a diameter and area. I would like to sum up the polygons per each plot area. From the attribute table, the polygons are not ...
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  • 49
3 votes
2 answers
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Finding nearest polygon in PyQGIS using QgsSpatialIndex

I am trying to write a custom processing tool for QGIS which joins the nearest attributes with some conditions. Therefore I'd like to use a QgsSpatialIndex to increase performance. This works ...
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Remove the longest segments of a polygon using QGIS

Is there an expression or tool that allows the user to remove the longest segments of a polygon? The end result would be two end segments (lines)
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How to make polygon shapefile from .csv file with ShapeSTArea and ShapeSTLength features?

I have a .csv file that includes x and y coordinates as well as ShapeSTArea and ShapeSTLength features. (see below) I'm hoping to turn this .csv file into a shapefile that instead of displaying ...
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1 answer
19 views

Enlarging gBuffer width changes polygon shape

I am having some issues with spTransform and the gBuffer function. I basically have a polygon that I want to buffer with gBuffer (not with st_buffer for other reasons). For some reason the shapefiles ...
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  • 9
2 votes
1 answer
32 views

Splitting feature into individual features in QGIS

In QGIS I have a layer that is made up of a large number of polygons that are merged together to form one feature. Is it possible to split this feature into the individual polygons that make it up so ...
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1 vote
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Selecting smaller polygons first into a QGIS Web map

Here is my issue, I am having a QGIS Map with polygons, I edited the symbology in order to stack the smaller area ones first so they can be clicked first to open the pop up window in the web map later....
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6 votes
6 answers
487 views

Selecting only one point in polygon using QGIS

I have two shapefiles: polygon(buffer) and point. How can I select only one point in each buffer in QGIS? If I use the "Select by Location", I will get all points inside the polygons, ...
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  • 521
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Draw polygon interactively in Python Dash and get zonal histogram/statistics

The problem I would like to be able to interactively draw a polygon on a choropleth map, where I can draw as many vertices as needed. After drawing the polygon, I would like to get back the zonal ...
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  • 45
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2 answers
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ArcGIS clip raster with polygon - keep only cells that are fully within the polygon

I am trying to clip a raster with a polygon. The raster has a very coarse resolution of 10m (and must remain with that). I would like to keep only the raster cells that are fully within the polygon (...
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4 votes
0 answers
66 views

Sorting points to create polygon in PyQGIS

I have list of points and I want to create a polygon. First I need to sort points for that I tried: Find the center point of all points Calculated angle from the center to each point, Based on angle ...
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11 votes
4 answers
555 views

Deleting small holes in polygons specifying the size with PostGIS

I have a big MultiPolygon layer in which I want to delete holes smaller than 100m². QGIS do it well and fast with the algorithm "native:deleteholes", but I need to use it as part of a SQL ...
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-1 votes
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Clip Line Layer to Polygon but retain the Lines outside the polygons

I want to clip a line layer to a polygon layer, but retain the lines outside the polygons. Can anybody assist me in doing this please? On the image included, the lines are in red and the polygon in ...
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Measuring length of polyline which overlaps polygon in ArcGIS Online

I want to measure the length of a polyline which is not completely within a selected polygon. I want only the length of the polyline which overlaps the polygon.
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QGIS 3.22.6 Add letters to check boxes instead of ticks when using value relation widget

I am using QGIS 3.22.6. I have added a species list to a polygon layer using the value relation widget. For each feature I am able to tick/select which species are present within the polygon. Rather ...
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0 votes
2 answers
17 views

Unable to join data from another layer

I have two polygon layers, I want to join the data based on the location from one layer to another layer. But only field is joining not the data. In image green is one layer and red is another layer. ...
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  • 259
2 votes
1 answer
77 views

How to get a list of lines, with a list of polygons that they intersect? [closed]

I am a new user in a PostGIS environment and don't even know where to start. I have two tables, one storing lines and the other storing polygons. I to create a query that can be used to get a separate ...
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2 votes
1 answer
72 views

Rotating by 90° one and more polygons in QGIS

I have a layer with many rectangles polygons, these should all be rotated by 90°. Can I do this in QGIS? I have not found a way so far.
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  • 159
0 votes
1 answer
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Split Polygon in one layer based on boundaries in second layer

I have two different polygon layers, 1 and 2. Now i want to split polygons in layer 1 taking reference from polygons in layer 2. Is it possible in qgis???? Please find attached image as reference ...
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  • 259
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1 answer
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Buffering polygons with Oracle Spatial 11 vs. 19

Does anyone have special knowledge about Oracle Spatial? I buffered polygons in Oracle-11 Database by making them slightly smaller (-50cm). The geometries are then delivered via a WFS as GML. With ...
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  • 1
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1 answer
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Wrong polygons displayed in QGIS spatial query

I have two polygons, one is a virtual layer that generates a buffer around a site, the other is a set of polygons representing locations of interest. I have tried to create a query that gives me only ...
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3 votes
2 answers
161 views

Selecting points which touch "boundaries" of another polygon using QGIS

I have an quite complicated polygon shapefile and a lot buffers around points (second shapefile). These small polygons are within and outside of the big polygon. I need to select those polygons which ...
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1 vote
1 answer
27 views

Looking for GeoPandas equivalents of PostGIS "ST_DumpRings" and "ST_Dump" tools

I have a GeoPandas DataFrame with a MultiPolygon geometry that I want to explode into separate line polygons. I do this by using: gdf.explode() I believe this equates to PostGIS's ST_Dump() but i ...
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  • 37
3 votes
1 answer
49 views

Split polygon by regard of distance to other shapefile

Is there some function that use distance to point/polyline layer to split a polygon layer In Sweden the law says that undivided water belongs to the nearest property so sometimes I need to calculate ...
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1 vote
1 answer
70 views

Read geo-spatial data in R via Leaflet

I have some site boundary data as follow: UNB_BDSB_SiBdry_v08_201028lico_25831.cpq UNB_BDSB_SiBdry_v08_201028lico_25831.dbf UNB_BDSB_SiBdry_v08_201028lico_25831.prj ...
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16 views

Polygon Vertices Pixel are not integers

In a GeoJSON dataset there is the column 'polygon_vertices_pixels'. It says it contains the pixel coordinates of the vertices of the polygon on the matching image. But these values are not integers. ...
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1 vote
1 answer
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Merging two polygon features (GeoJSON file) using QGIS

i've seen this tutorial that explains how to merge two polygon features in QGIS. Doing it works, but when I stop editing the layer, I got a message Could not commit changes to layer drawingPolygons ...
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  • 189
1 vote
0 answers
209 views

Shapely intersection between LineString and multiple Polygons

I am trying to get a function to return True when a LineString intersects with any polygon in a list of polygons. Currently, I am using a for loop to iterate through all the polygons and check one by ...
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0 votes
0 answers
22 views

Adjusting angles after drawing polygon in ArcMap

I need to adjust the angles of a polygon that I've drawn in the ArcMap environment. In fact, I've converted the polyline to polygon by using data management tools and features. Now I want to modify ...
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  • 1
3 votes
1 answer
64 views

Finding change between two sets of polygon data in QGIS

Say that I have two sets of polygon data: one depicting world borders in 1990 one depicting world borders in 2020. I have ensured that both data sets are under the same projection. Both sets of data ...
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  • 131
1 vote
0 answers
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Finding intersection between polygons in one shapefile using Shapely

I'm trying to repair invalid geometries in my shapefile. Before using object.buffer(0) method to repair them I need to extract geometries that intersect in-between with their whole surface cause I ...
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  • 33
2 votes
2 answers
81 views

Joining two polygons where they overlap the most in QGIS

I have two layers: district (with lots of districts) and an object layer. I want to add the information where the object lies in the most to the object. For example: this object lies the most in ...
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  • 23
1 vote
1 answer
137 views

Create sf polygon from sf linestring and bounding box

I want to create a polygon using a linestring within the sf universe. I am generating a map of a coastline and I want the area that is water to be blue and the area that is land to be tan. Because ...
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  • 2,006
0 votes
0 answers
75 views

Spatial indexes with RTree for polygons

I am trying to understand about how R-tree works for polygon data. In other words, polygon is a list of vertices (points), however, I am wondering how spatial index can recognize the order of points ...
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2 votes
2 answers
267 views

Using Shapely methods (explain_validity and make_valid) on shapefile

I'm trying to find and repair invalidity in my polygons. I have already found out that 10 polygons have self-intersection problems in QGIS, trying the same thing with shapely. This is my code: import ...
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1 vote
0 answers
17 views

How to cut polygons in ArcMap using manually entered coordinates?

I would like to cut polygons with a line determined by coordinates. I have the coordinates in a separate pdf file (for reasons beyond my control) and I would like to manually enter them during the ...
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  • 305
1 vote
0 answers
15 views

Polygon clipping with percentage tile membership

Let me setup the problem: I have a tiled world map (0.1° x 0.1°) with values assigned to each tile. I want to assign the values to each country, and I'm doing so by clipping to their ZEE mask. But ...
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4 votes
1 answer
102 views

Adding lines to polygons in QGIS

I'm mapping quick clay risk areas and have extracted areas which could trigger slides (slope > 1:2.5; height (min/max) > 5m). The areas are separated into zones of roughly equal aspect (30 deg), ...
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0 votes
1 answer
40 views

Extracting polygon features based on single layer attribute polygons using ArcGIS Pro [closed]

I have a single-point shapefile with gauging locations all around the world, and I also have a shapefile with country boundaries. See picture of files. How can I extract the point files that are ...
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  • 307
2 votes
1 answer
47 views

Speeding up a TIN to MultiPolygonZ conversion in PostGIS

I have a TIN record in a PostGIS database. It contains between 50'000 and 100'000 triangles: Based on this answer: https://gis.stackexchange.com/a/209845/65370 I'm trying for the moment to dump the ...
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3 votes
1 answer
272 views

How to get polygon coordinates of a searched place in GoogleMaps?

When you search a town on GoogleMaps , it shows a highlighted polygon area. How can i get coordinates of that polygon?
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  • 151
1 vote
1 answer
120 views

Identifying n-nearest polygons to point in GeoPandas

I have a dataset of fire polygons, and a user inputted lat/lon coordinate. I'm hoping to write a function to subset the 3 nearest polygons to the inputted coordinate, in order to report out their ...
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2 votes
1 answer
26 views

How to find which raster cells are overlapped by polygons

(QGIS 3.22) I'm trying to compare a raster layer with a vector layer and find all the raster cells overlapped by a vector. Unfortunately, the polygons are much smaller than the pixels of the raster, ...
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3 votes
1 answer
79 views

Appropriating ID for all lines inside polygon in QGIS

I have 12 Polygons with a lot of lines in every Polygon. The Polygon have each its own "ID". I would like to add the "ID" of the polygon to the lines it is containing.
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  • 41
2 votes
1 answer
52 views

Point feature class to multiple polygons

In my job, I am currently getting excel files with multiple polygon features in point format. Converting this to points, and then to a line feature class works absolutely fine when using the ID as the ...
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