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Questions tagged [polygonize]

The process of producing a polygon feature layer from a raster or from lines.

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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 ...
Freddy94's user avatar
1 vote
1 answer
45 views

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 ...
Phoebe's user avatar
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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 ...
andreaordonselli's user avatar
0 votes
1 answer
61 views

Raster to vector bunch of errors

I'm having a problem where I can't convert my raster file to vector using the raster menu, I'm kind of new to the area and some errors appear that I have no idea how to fix. I know I can do something ...
Leo's user avatar
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2 votes
1 answer
164 views

Polygonize error

I try to vectorize raster layer. Each pixel has value from 1 to 128. It the simplest and has only 1 band. I use polygonize tool and I get an error. Initially I got my raster from rasterize tool (...
grassu's user avatar
  • 53
1 vote
0 answers
36 views

Take colours from a raster image into shapefile

I have georeferenced an image in my project, it's a thematic map in PNG, then I have transformed it in shapefile (Poligonyze). I'm trying to take back the original thematism in the shp. Manually with ...
Bernardo Chiaravalli's user avatar
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20 views

Polygonize reclassified NDVI layer, how to remove sliver ploygons (QGIS)

I have calculated an NDVI layer, to create three categories (water, gravel, vegetation) that I can then polygonize. Now there is the issue that bright colored rocks and water have similar signatures, ...
beni 's user avatar
3 votes
0 answers
49 views

How to clean dangling ends from bathymetric lines so they can be polygonized? [duplicate]

Problem I want to turn bathymetric lines into polygons. However, the bathymetric line datasets have multiple dangling ends within them. Because of this, the 'Lines to polygons' or 'Polygonize' tools ...
Nick_K's user avatar
  • 31
5 votes
2 answers
118 views

ST_Polygonize creating single polygon

I have a situation that is very similar to the issue described here. However, the accepted answer does not work for me. I am essentially attempting to create polygons from contour lines generated ...
rumski20's user avatar
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0 votes
1 answer
308 views

QGIS Polygonize tool error

I am running into a error message with the Polygonize tool raster to vector. In taking an online course the instructor is asking us to use the Polygonize tool on a reclassified raster of a NDVI (...
user229443's user avatar
0 votes
1 answer
238 views

Raster to Vector GDAL raster conversion error QGIS 3.28

I'm trying to convert a raster layer with values 1 to 0 in vector layer using GDAL raster conversion - Polygonize (Raster to Vector) in QGIS 3.28. After processing i got an error at the Log window: ...
Iven Pepa's user avatar
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1 vote
1 answer
197 views

Raster to Vector using GDAL without dissolving vector data on like-features

Python beginner here. I am converting a raster to a vector in shapefile format. I am successful in doing this but my output isn't quite what I'm looking for. I need the output to have a "square&...
Connor Garrett's user avatar
1 vote
1 answer
181 views

Joining polygons from the same data source and create one smooth polygon in R

I would like to create on single polygon from multiple small polygons (see the image below which represents what I want) I need to connect the polygons and I found that purrr::st_connect might work ...
Camillionnaire's user avatar
1 vote
0 answers
53 views

Cannot call temporary layer while polygonizing a raster on PyQGIS

I been trying to call the resulting vector from the Raster Poligonization but it ends up telling me: Unable to execute algorithm. Could not load source layer for INPUT: */OUTPUT.tif not found ...
Roberto E.'s user avatar
1 vote
0 answers
78 views

QGIS: Should I convert raster dataset to vector and how?

I've a raster dataset of 20m² cells that show if a cell has been deforested and the year. I need to calculate the distance of each cell from a conservation project boundary, roads, canals (which are ...
sandy's user avatar
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5 votes
1 answer
323 views

QGIS: Lines to polygons not working

I have +1000 CityGML data with building height that I want to convert to a raster mask for deep learning. So far, I have converted the GML data into GeoJSON with its respective ID as linestring. Now I ...
user210818's user avatar
0 votes
1 answer
795 views

Intersect a set polygons/multi-polygons at once and get the intersected polygon

I have a Geopandas data frame with five multi-polygons geometries. Now, I want to intersect all the geometries at once and get the intersected polygon out of it. I tried using unary union and ...
data en's user avatar
  • 145
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0 answers
145 views

Merge many small polygons into larger shapes

I'm trying to build a landcover layer from the ESA Land Cover dataset. So far, I have been able to convert the image data to a bunch of very small polygons. But for my use, I really just want a "...
Craig Kochis's user avatar
2 votes
1 answer
327 views

Validation of Vector Geometries to OGC Standards

I'm currently using FME to validate geometries, coming from 3rd parties, making sure there to OGC Standards. I was hoping to be able to replicate these checks in QGIS, but find the tools available (...
Richard McDonnell's user avatar
2 votes
0 answers
874 views

How to create a boundary polygon around raster extent (.tif) in QGIS

I would like to create a polygon around the raster (.tif) extent so I can calculate for instance the area in m2 within the polygon. When I try to Polygonize or Clip raster by extend (and delete the 0 ...
Aurora's user avatar
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57 views

Polygonize a vertical plane defined by a MultiLineString Z in PostGIS

I have to polygonize a vertical plane defined by a MultiLineString Z: SELECT ST_AsText((ST_Dump(ST_Polygonize(ST_GeomFromText( 'MULTILINESTRING Z (( 0 0 3, 1 1 3, 2 2 0, ...
swiss_knight's user avatar
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2 votes
1 answer
313 views

Remove small pixels in raster without leaving a gap

I have converted a raster to shapefile (polygonize) in QGIS and now have some areas that are salt and pepper with small points. I want to absorb these into the large polygon around the pixel (polygon)....
RJM's user avatar
  • 21
2 votes
1 answer
813 views

Shapely polygonize over a MultiLineString returns 0 geometry

I need to polygonize a linestring feature. To this end, I'm using the polygonize function of Shapely '1.8.5.post1' in Python 3.10.6. from shapely import wkb, ops as sp_ops wkb_str = '...
swiss_knight's user avatar
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-1 votes
1 answer
374 views

Creating polygons from an RGB image in QGIS

I scoured the QGIS documentation and couldn't find anything. What I am trying to achieve is a polygon covering a certain area, in my case, it's a glacier. The imagery of the glacier comes in the form ...
TooShort's user avatar
1 vote
1 answer
320 views

Filter small raster areas computationally efficient (with R/gdal)

I have a large geotiff with NDVI differences (values -10'000 to +10'000), that I use to create polygons. My workflow currently is to polygonize a binary mask of it and then filter areas that are too ...
Honeybear's user avatar
  • 2,474
2 votes
1 answer
335 views

QGIS - How do I select features in a particular location precisely, the location is a raster

I have polygon data that is data retrieved across whole world, how do I focus this data on a raster map. Basically I want to select the features only in this area but I want it to match exactly this ...
AhmedTech's user avatar
3 votes
2 answers
369 views

QGIS - Converting Vector to Raster and back to vector to resample resolution of vector data

I would like to convert my polygon data into a raster file to change the pixel resolution and then would like to convert it back to polygon data since this will allow it to be resampled to another ...
AhmedTech's user avatar
1 vote
0 answers
40 views

Transform Lines to Polygons QGIS - FEMA SFHA

I am very new to GIS. Using QGIS LTR 3.22 I have downloaded the FEMA SFHA Shape files from FEMA's website. There are a few layers but the specific one I am working with is the S_FLD_HAZ_LN layer. ...
Avraham Schwalb's user avatar
1 vote
1 answer
138 views

no feature ID when polygonizing raster with python GDAL

I'm trying to polygonize the following binary raster: The output is a polygon layer (ESRI shapefile) that looks good, however, doesn't have FIDs for the features and thus I am not able to iterate ...
mnowatzki's user avatar
2 votes
0 answers
246 views

Polygonize tool error "Process gdal_polygonize.bat failed to start"

I am trying to use the Polygonize (Raster to Vector) tool on QGIS-LTR on Windows 11. When I launch the tool on a layer I get the following error. Input parameters: { 'BAND' : 1, 'EIGHT_CONNECTEDNESS' :...
Elia's user avatar
  • 21
0 votes
1 answer
402 views

Polygonize/Vectorize large raster

A raster(.tif) of 6.70GB needs to be converted into polygons. The raster is binary (0 & 1), currently I am using Polygonize (raster to vector) and its taking a considerable amount of time and the ...
N_LLC's user avatar
  • 615
0 votes
0 answers
132 views

QGIS Polygonize not working on large dataset

I have a 1.3 gigabyte shapefile I am trying to run through the vector polygonizer in QGIS. The lines intersect each other yet when I run it through it gives me "No polygons were created." Is ...
strayberry's user avatar
0 votes
1 answer
180 views

Polygonizing global raster using Python/GDAL?

I'm looking to polygonize a global raster with 29 different categories. However, when I try to run it in QGIS, it either crashes or takes forever to load. I'm now trying to run it in python. import ...
user2031's user avatar
  • 221
0 votes
1 answer
104 views

Classifying areas after feature to polygon

I am trying to classify areas based on the polygons created from using two separate lines as input in ArcGIS Pro's Feature to Polygon tool. The input looks like this first column in the image from the ...
bashful_creature's user avatar
3 votes
1 answer
63 views

Polygons from lines with manually completed lines using vertex tool and snapping

I have a vector layer of lines (contours) which was a model output. Some contours are incomplete due to land barriers (necessary for the model) which produces something like this I have used the ...
Jojo's user avatar
  • 141
2 votes
1 answer
772 views

Converting complex depth contours to polygons in sf and R

I have a large dataset of depth contours downloaded from an open database. At the time of writing, these contours appear to contain the best available continuous depth model for my region of interest. ...
Mikko's user avatar
  • 374
2 votes
1 answer
2k views

Convert area between LineStrings to Polygon in shapely

I need to create a Polygon from the area enclosed by four LineStrings with real world data in shapely. In this example, I want to polygonize the area between b1, b2, t1 and t2. import shapely.wkt b1 = ...
eimes's user avatar
  • 43
3 votes
1 answer
458 views

Joining a very large raster and shapefile in QGIS

I am using a very detailed 30 m x 30 m raster on deforestation (found here: https://storage.googleapis.com/earthenginepartners-hansen/GFC-2020-v1.8/download.html), I want to do all my analysis at this ...
Neha's user avatar
  • 31
2 votes
1 answer
5k views

How to extract the boundaries of Shapely MultiPoint? [closed]

I have a shapely MultiPoint object but need to extract the boundaries into a Polygon object. I'm currently using the convex_hull of the MultiPoint object but my MultiPoint sets can have sharp inward ...
jorrebor's user avatar
  • 221
4 votes
2 answers
976 views

Extracting polygons from scanned GeoRef images based on colours in QGIS

I would like to extract a polygon based on it's colour from a scanned map georeferenced in QGIS. In the image, I would like to extract all of the blue as a separate shapefile/GeoPackage instead of ...
Jasper Mowatt's user avatar
1 vote
2 answers
10k views

How to apply GDAL polygonize?

I am desperately trying to vectorize raster files in a loop for which I came across GDAL's polygonize function (https://gdal.org/programs/gdal_polygonize.html). However, I don't get the hang of it. To ...
Stücke's user avatar
  • 539
0 votes
2 answers
600 views

How to polygonize NDVI raster using GDAL?

I have raster with NDVI values. I would like to polygonize the raster to get vector where each polygon is a pixel. I have tried gdal.Polygonize as described in the documentation and that runs without ...
ReutKeller's user avatar
  • 2,169
2 votes
1 answer
639 views

PostGIS: Split polygons into intersecting and non-intersecting and grouping on overlap

I have a big query that I am looking to optimize. I am matching millions (expanding daily) of rows with Points against a mostly read-only table of (tens of thousands of) areas with (Multi)Polygons. ...
Goddesen's user avatar
2 votes
1 answer
49 views

Saving polygonized raster file to shapefile failed

I have a raster that I have polygonized (raster to vector) with QGIS 3.20.3. The result is a temp layer that can be displayed in the canvas. When I try to save the features to shapefile it runs until ...
oppia04's user avatar
  • 735
2 votes
1 answer
1k views

How to get float values instead of integers when polygonizing rasters using QGIS?

I'm using QGIS 3.16.13-Hannover to convert a TIF file (solar radiation grid cells) into a vector like a Geojson or Shapefile. I was confused that everytime I ran the polygonize workflow in QGIS, I was ...
Kyle Pennell's user avatar
0 votes
2 answers
1k views

Calculate area for each raster value within a polygons (python) [duplicate]

I have a raster file and polygon shapefile. I need to calculate area for each raster value within a polygons. Example: the polygon below Total area = 1000 ha. I need an area for each raster value in ...
g123456k's user avatar
  • 600
0 votes
1 answer
341 views

How to add a border around a GeoTIFF?

I have a 200x200 GeoTIFF from which I am trying to create multiple polygons. I am using different range values to generate different polygons. However, the inverse of the polygons I want are being ...
Vid1324's user avatar
  • 21
3 votes
1 answer
271 views

gdal_polygonize / QGIS Polygonize creates

The original data is a pdf converted to tiff then georeferenced. Then i did the sum of the 3 colors band to simplify the calculus When i launch the polygonise (raster to vector), this is very slow ...
jlSta's user avatar
  • 1,096
3 votes
1 answer
339 views

Looking for QGIS equivalent of ArcGIS "Feature to Polygon" tool

I am looking for a tool (a workflow) in QGIS that does exactly the same as the "Feature To Polygon" in ArcGIS available with the Advanced license. I have seen a related question Seeking ...
Taras's user avatar
  • 33.3k
1 vote
1 answer
221 views

Extract altitude bands (polygon) from DEM (GeoTIFF)

I'm trying to extract altitude polygons from a DEM - 0 to 1000m, 1000 to 2000m, etc. I'm not sure what this is called (noob question, yes I know), and can't find help that points in the right ...
Werafa's user avatar
  • 138

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