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Questions tagged [v.clean]

v.clean is a Grass GIS algorithm which allows the user to automatically fix topology of vector maps.

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How to associate point to most recent date in overlapping polygons? (Union & v.clean is giving errors.)

I am trying to associate presence points (where a bird was sighted) in a given month (e.g. December 2022) to the most recent fire that occurred in that area. I am planning on generating a raster (5km ...
Frek's user avatar
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1 answer
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QGIS Having an issue with v.clean/snap removing existing geometries when trying to snap undershoots

I'm running v.clean on a merge of 2 vector layers of pipeline data. I initially found the issue trying to clean undershot laterals not properly attached to main lines, scale is undershot by about 1 ...
Derek_P's user avatar
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Use v.clean function from GRASS in Jupyter Notebook

I want to automate a process which involves using v.clean tool from GRASS inside a Jupyter Notebook. I've read documentations on how to use Python with GRASS, but it seems impossible to do it or I don'...
Freestyle Season's user avatar
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v.clean (GRASS) creates additional features

I am working with a large road dataset (approx. 1 million features) with a high number of overshoots and dangles. To address the overshoots and dangles, I am using the v.clean tools (break, snap, ...
Julia Cardwell's user avatar
1 vote
1 answer
289 views

Removing gaps between line features with v.clean in QGIS

I want to fill gaps between line features with v.clean. It works for the small gap (0,015m) but the 10-meter gap will not be closed. These are my parameters: Test available here: data shapefile
Barrylim_work's user avatar
2 votes
1 answer
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Aggregate (dissolve) polygons leaving internal lines - R

After dissolving polygons, some of the internal lines remain. It seem to be a problem common also to ther softwares (ArcGis and Qgis at least). The dissolve result is this: To dissolve using R, I'm ...
Oalvinegro's user avatar
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177 views

How to delete gaps but not change polygon boundaries with v.clean in QGIS?

So I am trying to get rid of gaps between a large number of polygons in QGIS using v.clean. I am able to successfully run the tool but the boundaries of very thin polygons end up changing quite ...
Ian Moffit's user avatar
1 vote
1 answer
115 views

v.clean rmarea resulting in empty result

I got some issues with v.clean in QGIS. I try to get rid of small polygons in a vectoriced raster layer. The Layer got one column with integers with value 0 or 1. I use: { '-b' : True, '-c' : False, '...
sfetan's user avatar
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1 answer
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What am I doing wrong with v.clean in QGIS 3.22 LTR?

I am trying to use v.clean to fix small overlaps and gaps in a polygon dataset. However, I always get an empty output. What am I doing wrong? I've tried different thresholds but the result is always ...
parallax's user avatar
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2 votes
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Why does Dissolve tool create little holes in the resulting polygon?

I tried to dissolve a couple of polygons and found out that it creates little holes in the Polygon (see: QGIS Dissolving and holes). I knew how to 'fill' the holes (with v.clean) but I am wondering ...
eagleadmiral's user avatar
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Unable to aggregate line segments while summing values

I've a layer with multilines, overlapping to a various degrees. I need to merge/dissolve them "downwards" while summing their values for the overlapping segments. I made it to "Union&...
edge's user avatar
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3 votes
1 answer
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Using v.clean crashes QGIS

I am working on a shapefile depicting English administrative divisions in QGIS 3.16.15. I began first by using the 'Fix geometries' tool to remove invalid geometries. Then, I used the topology editor ...
Calum Loftus's user avatar
1 vote
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297 views

Generating line features with "must not have dangles" constraint in QGIS

I am making line features in QGIS and sometimes, if I work inaccurate, they have dangels (loose ends). That is what I want to avoid. There are ways to detect dangles after creating a feature (topology ...
Quarantäne's user avatar
2 votes
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70 views

How to automatically clean hollow lines in middle of polygons in QGIS?

I am trying to correct automatically this kind of errors. I already tried the tools v.clean (maybe I have to tune some parameters?) and correct geometries. I also tried dissolving, but since there is ...
Alvaro Morales's user avatar
4 votes
2 answers
2k views

Why is v.clean not working?

I’m trying to clean the snapping errors from my line layer. I have a problem with running the tool and the outputs. During the run, many errors and warnings arise. I tried to use the tool in both UTM ...
OpalK's user avatar
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1 answer
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Fixing dangles (lines) with v.clean and "fix geometries"

I need help with fixing my two dangle-errors: there are 2 dangles on the top right and one small hole on the top-left corner. I can deduct them with the Geometry Checker, but I cannot fix it (...
Carina's user avatar
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3 votes
2 answers
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How to use v.clean in QGIS to fix polygon topology

I have QGIS 3.18 Zurich with GRASS 7.8.5 installed on my 64bit Windows machine. I have digitized 1600+ polygon boundaries that now have sliver polygons, gaps, and overlaps which I've confirmed via the ...
BenW's user avatar
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2 votes
1 answer
844 views

v.clean cleaning topology

I'm doing some tests with the v.clean but getting some results that I don't really know if I am the one doing something wrong or what. As you can see in the image bellow I created 3 features, one with ...
Felippe M.'s user avatar
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4 votes
1 answer
526 views

Problems with cleaning the topology of a shapefile using GRASS tools and snapping tools

I have a shapefile with almost 1000 polygons (each polygon representing a farm). There are a lot of topological errors (gaps/slivers and overlaps between polygons). Below is a "zoomed in" ...
Stef's user avatar
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4 votes
1 answer
444 views

Automatically join lines by snap

After I smoothed a layer of lines I lost the connection with some vertices. Is there an automatic way to connect the various lines to avoid doing it manually? I think the best thing is to use v....
ddomizia's user avatar
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V.Clean is not giving output In QGIS 3.14 Pi

I was trying to clean by removing sliver lines between set of polygons in my KML file. But unfortunately I am getting following error: QGIS version: 3.14.15-Pi QGIS code revision: d5114d2cfa Qt ...
Manoj K E Manoj's user avatar
3 votes
1 answer
254 views

v.clean is stuck at 0%

So I have a layer with thousands of gaps and overlaps that I want to tidy up, but when I go to run v.clean in order to do so, it just sits there at 0%. I have no warnings or errors in the system, and ...
Spencer Brownlee's user avatar
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1 answer
326 views

R: read and clean layer with v.clean (using rgrass7)

I'm trying to execute some rgrass7 processing from R but I can't even get the first process done. I would like to clean a vector line layer. The goal here is not just to clean the topology, that's ...
César Arquero Cabral's user avatar
7 votes
1 answer
2k views

Cleaning small artefacts from polygon shapefile

With some success, I've been generalising and cleaning Ordnance Survey OpenData VectorMap District woodland polygon shapefiles to make them fit for mid-scale mapping. However, the resulting shapefiles ...
nhopton's user avatar
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