Questions tagged [topology]
Topology describes non-metric relationships among geometric figures, such as adjacency, containment, and orientation. It is a branch of Mathematics, which deals in geometry without measurement.
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Preventing polygons from overlapping after splitting them in QGIS
I have a FileGDB with several polygons. When I split them using the Split Features-Tool, they overlap with other polygons within the same layer I did not split.
Here are some screenshots:
Original:
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How to create line topology from-node to-node table fields?
We are looking for a way to create line topology from-node and to-node attribute fields on a shape file as shown below. We know that ArcHydroTools GenerateFNodeTNode can do it, but want to avoid ...
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Bulk-removing self-overlapping polygons
Using QGIS 3.18, I ran the topology checker on a polygon layer (gpkg format). It found several thousands self-intersections.
I can see the errors, but I cannot seem to be able to delete the polygons ?
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Finding lines that fold over themselves
I'm working with a dataset provided by a third party and have found some lines that fold back on themselves (or in some cases, almost fold back on themselves)
For example, this line folds back over ...
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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 ...
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Node information in a PostGIS dataset
I am working in QGIS / PostGIS to plan the cable layout for a seismic array. The power distribution is from the green point with the white cross in the middle. The nine green points marked with a ...
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Topology checker won't highlight in red the overlaps
I´m using QGIS and trying to find overlaps in a shapefile.
When I use the Topology Checker I get 24 results for overlaps, but they are not highlighted in red as they used to the last times I did the ...
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Topology-aware "waviness" for polygons in QGIS
I am wondering if there is any chance to create "wavy" polygons that respect the topology. In a polygon-layer where the individual features shares boundaries you can easily style each ...
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ArcGIS Pro - routing, remove short network elements and reconnect edges
I am setting up an ArcGIS Pro network for use in Network Analyst. So far things work pretty well, depart from some 1600 errors due to this kind of problem: "
SourceName: linknetz, ObjectID: ...
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Select building facades that face the street
I have a set of buildings (building footprints) and a street network. The buildings have attribute
Use. I need to transfer the value of attribute Use as well as the length of the building façade that ...
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Are there ways to speed up building large topology datasets in PostgreSQL/PostGIS?
I used this stored procedure to create a topology for all Census block groups in the contiguous US. It took almost 136 hours to run (on a fast, dedicated workstation - Ubuntu 23.04, PostgreSQL 16, 128 ...
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Cryptic PostGIS/GEOS topology error
I'm attempting to determine 1) what "ring edge missing" means in the following PostGIS/GEOS error message, and 2) why ST_Intersection throws it for certain gridSize parameters but not for ...
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Vector layer is showing gap which is not marked in red, how to correct the problem [closed]
I am working in a QGIS layer with more than 450 polygons. When I am checking with the topology checker for any error, it shows two gaps, but they are not visible in red, and one polygon is being ...
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Quickly remove overlaps from two polygon layers in ArcGIS Pro
I have two polygon layers (both very large, up to 1 million rows). One is cadastre (lot boundaries) and the other is building footprints. The latter is rather inaccurate (MS / Daylight layers but is ...
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How to resolve dangling end between two lines using QGIS
(It goes without saying, I am a beginner with all of this!)
I have a QGIS (version 3.28.11-Firenze) file into which I imported a KMZ from Google Earth. The purpose of this is to produce a shapefile ...
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