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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19 views

Automatically Remove Overlap using Error Inspector

I use Topology-rules and Error Inspector to remove errors in my map, duplicate lines etc. I often have hundreds of small errors. When available fixes are "Split" I can select all rows and ...
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0answers
38 views

Adjusting tolerance of topology checking using QGIS

I have a problem, the topology checker shows very tiny overlaps between polygons (under 0,000001 qm). For our project we just want to see detect the relevant overlaps, which are more than 0,01 qm. ...
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1answer
82 views

Allow overlapping polygons in QGIS [closed]

When I draw a polygon in QGIS that overlaps an existing polygon from the same layer, QGIS automatically clips the overlapping area from the new polygon. Is there a setting to preserve the shape that I ...
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3answers
277 views

Redistributing duplicated points inside the polygon

I have a point layer with real estate data, obtained after geocoding by addresses. In case of multi apartment housing all points with data for several apartments in one building has identical ...
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59 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 ...
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2answers
146 views

Topological editing of vertices that are common in two adjacent polygons in QGIS

How do you edit vertices that are common in two adjacent polygons in QGIS? I tried to select both polygons but when editing the vertex moves only in one polygon and not in both.
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1answer
78 views

Maintaining topology on MultiLineString

I'm trying to get topological movement of lines with Leaflet-Geoman plugin using TopoJSON. There is a method called topojson.mesh , which Returns the GeoJSON MultiLineString geometry object ...
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1answer
45 views

Showing the exact overlap area in Topology Checker QGIS

I am using the Topology checker in QGIS 3.10.11 to find overlaps in a large polygon layer. How can you get it to show you exactly where the overlap is? It just shows me there is an overlap somewhere ...
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1answer
58 views

Unique attribute value across multiple layers

We are in the process of cleaning up our asset database which contains day 20 of layers generally in file geodatabase format and includes point, line and polygon types and some non spatial tables. Is ...
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1answer
71 views

PostGIS TopologyException error when all polygons pass ST_IsValid test

I am getting this PostGIS error: ERROR: lwgeom_unaryunion_prec: GEOS Error: TopologyException: Ring > edge missing at 577690.01999999955 213605.69999999925 SQL state: XX000 I have checked that ...
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60 views

How to solve the error "ERROR 160196: Invalid Topology" when running the split tool

I am trying to split a multipart features using Split (Analysis) tool. When launching the process I come across the error message "ERROR 160196: Invalid Topology. Failed to execute split". ...
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1answer
108 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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0answers
57 views

QGIS crashes when I try to check for double or check for crossing lines

I have a LineString layer that I want to check for double geometries and/or intersecting lines. I've tried two different tools (Check Geometry (Geometryprüfung) and Check Topology (Topologyprüfung)) ...
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1answer
26 views

v.clean what input feature type for polygon?

I have a polygon layer where the Topology Checker detects hundreds of overlaps and tiny gaps. So I want to use the v.clean tool to clean the topology. For cleaning, I selected the tools bpol, rmarea ...
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2answers
180 views

Geometry vs geography vs spheroid for polygon-contains-point (PostgreSQL)

Many operations behave differently in geometry vs geography, e.g. the distance between two points. But what if I only need to check whether a polygon contains a point? Does that operation differ ...
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0answers
41 views

Split intersections of lines considering bridges and tunnels

I want to make a road network routable. I already have a road shapefile, but there are many intersections of lines that I want to split. Now I have two problems: (1) My first approach to split them ...
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107 views

Snapping and topological editing in QField

Suppose I have a project with two layers, cemeteries and poly. Also, let's call cemeteries something else: hypotheses, because that makes things a bit clearer. I would like to edit these layers in ...
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2answers
489 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 ...
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1answer
96 views

Is topology stored explicitely in vector layers or is it derived from stored geometry information?

In vector layers, different types of information are stored like: Geoemtry Attribute data Meta data (like filename, projection etc.) Spatial indices However, what about topology? Is it an explicit ...
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1answer
78 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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1answer
106 views

Determine whether a polygon is completely surrounded using QGIS [closed]

I have a shapefile dataset of polygons. I would like to find those polygons that are completely surrounded/enclosed. Mathematically, this means that the perimeter of Polygon A should equal the sum of ...
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0answers
29 views

Identifying topology error with Javascript

ArcGIS has tool to fix topology errors. Does any JavaScript gis package have similar function? I have tried two packages. OpenLayers has the function to build topology from geojson TopoJson can ...
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1answer
77 views

Making vector geometries "Kiss" in QGIS

I am working with vector geometries that I recently simplified using the native:simplifygeometries method in the processing toolbox. I am pleased with the simplification but I want to "fill" ...
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2answers
178 views

Simplify polyline by arcs and lines

I work in the construction industry and have a couple of software tools specific for the field, namely AutoDesk products Revit, AutoCAD and Civil. Presently, I have come across the problem of ...
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0answers
238 views

Error while removing gaps with v.clean in QGIS

I have a polygon layer (Geopackage with 378 features in EPSG:3857) with many very small gaps between them (topology checker lists more than 5000). The gaps are in a range of several hundred meters to ...
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0answers
68 views

Simplify/generalize vector geometry with side bias

I have contour polygons as vector geometry with attached elevation attributes. Is there a method to simplify vector polygons while preserving topology and elevation bias? By elevation bias I mean that ...
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0answers
36 views

Edit topology network

I have two SHP files in QGIS project (points: NODES.shp and lines: BRANCH.shp). NODES.shp has one ID attribute NODE_CON. BRANCH.shp has attributes NODE1 and NODE2 which represent start and end node of ...
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1answer
94 views

How can I split my polygon file into topological boundaries?

This question was asked 8 years ago, but the algorithm in the accepted answer is gone. (How do I split polygons into line segments?) So how can I split my polygon file into "segements"? The ...
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1answer
40 views

Snapping two topology layers together based on point

In QGIS 3.14.15 with GRASS 7.8.3 I have two layers both with correct topology that function how they should. When using the Network Analysis > Service Area tool, they work as they are supposed to. ...
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2answers
57 views

Polygon topology validation in ArcGIS - whole study area artefact problem

I have no experience with topology validation in ArcGIS. I have polygon feature class. When I create topology for this feature class, I specify two topology rules : Must Not Overlap Must Not have ...
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1answer
60 views

Moving point feature and vertex from polyline at the same time

I have two layers in QGIS 3.14: one with point geometry one with polyline geometry The point geometries (p) have the same coordinates as some of the polyline vertices (v): (v)--------(v)----------(v/...
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1answer
38 views

Finding intersection errors based on attribute value using ArcGIS Desktop

I have a road network table in a PostgreSQL database. The table has a level attribute which marks if a road is on the surface or if it is an under- or overpass. I would like to check the topology of ...
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0answers
23 views

How can you completely cover the surface of a raster with circles where the radius of the circle is the raster value at its centroid?

This is more of an algorithmic/math problem, but I was wondering if someone could point me in the right direction. There's the common problem of covering a surface with circles of equal sizes, but ...
5
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1answer
412 views

Export topology checker results as table/shapefile in QGIS

I have used the plugin "topology checker" and I got table with all the topology errors : I would like to save this table as new layer/ csv or any way I can export it. I saw there were ...
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0answers
44 views

Finding the LineString Corresponding to a Certain Road in a Roads Database

I am using tiger line road data to find roads that runs through certain points. I know what road is immediately next to the point by the road name and road type. What I currently do is grab all the ...
4
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3answers
182 views

Solving Traveling Salesman-like Problem

I own a (very) small appliance service company. It's just me. I cover roughly a 20 mile radius from a my office. Customers can sign up on my website for service calls anywhere within my service area. ...
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1answer
35 views

Customizing basemap in ArcMap

Using ArcGIS Desktop 10.7. I would like to customize the World Terrain Basemap in order to select which roads and topography labels appear. Is there a way to do this, and if not, then how would I ...
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1answer
107 views

ArcGIS - Eliminating slivers/gaps automatically

I have a land map with three labels (sand, vegetation and water). I wish to eliminate overlaps and gaps between these labels. There are tens of thousands of gaps and overlaps, so I need to automate ...
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0answers
29 views

Can you define a topology rule between two feature classes from different feature datasets?

I work in a project that I want to define topology rules between feature classes from different feature datasets, is that possible ? if no is there a solution that can do that ?
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0answers
63 views

QGIS Features to polygons

I would like to know if there is any equivalent on QGIS for the ArcGIS function 'Features to Polygons': https://desktop.arcgis.com/en/arcmap/10.3/tools/data-management-toolbox/feature-to-polygon.htm ...
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1answer
23 views

How to modify contiguity matrix in ArcGIS?

Is there any way to modify the contiguity relationships between the polygons in ArcGIS. I am thinking about a topology database that lets the user modify the data on the map? For example, if there is ...
2
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0answers
65 views

Automated polygon sliver removal

I am in the process of cleaning a large polygon dataset. This dataset represents the extents of an electrical network from a substation. The polygons have not been created correctly and there are ...
3
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1answer
197 views

v.generalize does not affect some boundaries

All in all, I would describe myself as a QGIS (3.12.2) beginner and have now contact with GRASS (7.8.2) for the first time. I want to simplify the boundaries of my polygons considering the topology. ...
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1answer
148 views

QGIS topology checker - check if point features are covered by line features

I want to use the topology checker to check if point features are covered by line features. For example are the bus stops covered by the bus lines.Therefore I use the topology checker with the ...
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0answers
23 views

QGIS - error added after processing

I use the "difference" processing beetwen 2 layers to have polygons of layers A that do not intersect polygons of layer B. In these 2 layers there are not bad geometries and topology is cleaned. I ...
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1answer
42 views

Problem with geometry checker plugin

I've used Geometry Checker Plugin to find some errors in my work. I have points that are connected to each other by lines. Among the parameters entered in the plugin there is "point covered by line". ...
2
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5answers
1k views

Find overlapping lines in same layer

I try to identify overlapping lines in the same layer with QGIS. My problem is that the lines are the same shape but not the same length. Maybe you can understand it with the picture below. These are ...
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0answers
20 views

ArcGIS tool to connect colinear polylines

I have a SHP file with thousands of polylines. Many are colinear (i.e., Line-A Endpoint-1 is same location as Line-B Endpoint-2). Sometimes they are colinaer across an intersection (as in image below),...
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0answers
59 views

Enforce Topology Check PostGIS

I would like to know if in PostGIS is possible to define spatial constraints for avoid topology errors? I have a polygon table and I need to avoid self-intersection and gaps. Does anyone know more ...
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1answer
159 views

Eliminating sliver polygons automatically [closed]

I have thousands of sliver polygons outside of my study area. What is the best way to eliminate them automatically? In ArcGIS or QGIS. Those polygon islands are an example of the slivers. Note: I can´...

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