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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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 ...
0 votes
0 answers
97 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 ...
1 vote
1 answer
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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, '...
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1 vote
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 ...
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2 votes
0 answers
76 views

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 ...
1 vote
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66 views

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&...
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3 votes
1 answer
95 views

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 ...
1 vote
0 answers
154 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 ...
2 votes
0 answers
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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 ...
4 votes
2 answers
644 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 ...
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4 votes
1 answer
365 views

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 (...
  • 157
3 votes
2 answers
2k views

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 ...
  • 613
2 votes
1 answer
285 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 ...
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4 votes
1 answer
222 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" ...
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4 votes
1 answer
115 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....
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0 votes
0 answers
315 views

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 ...
3 votes
1 answer
123 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 ...
0 votes
1 answer
188 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 ...