Questions tagged [polygonize]
The process of producing a polygon feature layer from a raster or from lines.
262 questions
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Polygonize not registering line intersections
I am trying to turn contour lines into polygons but when I try the polygonize tool it registers most of the lines, but skips parts of others. It appears that all the skipped parts occur around ...
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How to create a best fit circle through polygon using QGIS
I have an approximately round, but still irregular polygon. I would like to use QGIS to approximate this polygon with a circle using the least squares method. I have currently only found the ...
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Convert vector (points, lines, polygons) data into one whole polygon layer
The vector data in the left image consists of traffic signs, road lines, sidewalks, etc.
I want to make a big polygon where all the datas are located.
I've tried "Convex Hull", "Minimum ...
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Obtaining an empty output when transforming raster to shapefile using Python
I am trying to convert a raster data to a shapefile. However, when I do it and I import the output (shapefile), my shapefile is empty. This is the code I am using:
import geopandas as gpd
from osgeo ...
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Getting line to polygons algorithm work in QGIS
I'm new to QGIS and trying to make a map of the Roman Empire. I first copy a select of the coast and then close it with a line. But even for islands that I don't touch, when I run the line to polygons,...
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"Geometry error: One or more input features have invalid geometry." error when polygonizing in QGIS
How do I fix this raster that I aim to polygonize via QGIS?
For context, the raster is created from DEM STRM data. I tried to check whether the reclassification is the issue but the general log ...
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Converting black and white pixel raster to lines or polygons
I have a black and white bitmap pixel image (gif) of historical election precincts in Germany. I don't know the coordinate system, but EPSG:3035 is coming relatively close.
But even if we just assume ...
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Cropping vector by raster in QGIS
I have a vector shapefile consisting of polygons and I want to crop it in QGIS by a raster layer of a smaller spatial extent, where the polygons do not extend beyond the raster edge. I have tried the ...
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"UnicodeDecodeError: 'utf-8' codec can't decode byte 0x82 in position 85: invalid start byte" error when polygonizing WMS in QGIS
I am trying to polygonize a raster layer but I have an error. Here is the log:
QGIS version: 3.36.3-Maidenhead
QGIS code revision: 2df96554
Qt version: 5.15.13
Python version: 3.12.3
GDAL version: 3.9....
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Raster to polygon in QGIS - How to Poligonize using a limit of vertices
In ArcGIS, when I use the Raster to Polygon tool, I can set the Maximum vertices per polygon feature parameter, where the algorithm subdivides a polygon into smaller polygons. For example:
The result ...
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Connect ends of parallel line features to form polygons
I have a shapefile consisting of many sets of parallel line features. Each set has a unique ID. I want to close the ends of each set of parallel lines and create polygons. Is there a way to do this ...
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Converting polygon annotations to vector layer in QGIS
In QGIS I mapped a large flood basin as a polygon annotation, not realizing that it would have strange properties. Is there any way I could convert this polygon annotation into a vector layer e.g. a ...
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"Could not load source layer for INPUT: memory: not found" error in Processing Script using PyQGIS
I have a workflow where a raster should be polygonized and afterwards simplified. The simplified vector should be saved as a shapefile. I am using the template script from QGIS to create a processing ...
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Create vector layer using specific cells from a raster
I need to create a point layer from a big raster layer in QGIS. I only want points on the pixels with a '1' value, rather than have a point in EVERY cell (which apparently will take a day to process ...
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Starting from a DEM raster, is it possible to arrive at a polygonal layer with a slope greater than 30% not in squares?
On this site it is possible to download DEM maps of Italy with an accuracy of 10 meters: https://tinitaly.pi.ingv.it/Download_Area1_1.html
Bringing this raster into QGIS and running the Slope command ...
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