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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ogr2ogr (or other) simplification of polygons with shared boundaries

I am trying to simplify a collection of 100,000 or so polygons containing nearly 4 million vertices. The data is stored in a 2GB shapefile so there is no explicit representation of the topology ...
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54 views

Randomized organic warp of adjacent polygons that preserves topology and fixed nodes

I'm looking for algoritms to modify a set of polygons to make them appear more organic. They still need to maintain their topology and furthermore some of the nodes might be fixed. Please see the ...
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1answer
230 views

Creating consistent topology using PgRouting

I'm developing an application that needs routing information for certain cities. First, I downloaded a openstreetmap datafile (*.osm) and then I imported it into a PostgreSQL database using ...
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44 views

Topology checker - whole polygon highlighted rather than polygon segment

When I check for overlaps, topology checker is only identifying errors at the polygon level but not the polygon segment where the errors exist (the whole polygon is highlighted in blue). I believe ...
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0answers
161 views

Generalizing / simplifying multipolygon in PostGIS without missing polygons?

By following the rules from this site, I got the output but some polygons do not come within the simplified polygon. I think the problem is with topology. Is there any solution?
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599 views

Find / select / delete dangles in QGIS

Via Topologie Checker I'm able to find dangles, but there is no way to select them to edit or remove. Is there an other way to find and select?
3
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1answer
116 views

Fixing self-connect polygon in QGIS 3.2

I'm trying to clip a soil map layer and am getting invalid geometry that affects my clip result. The problem appears to be a self-intersecting polygon. I've tried using the 'check geometries', and ...
3
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0answers
107 views

Dealing with bridges over roads in PostGIS topology?

first time posting please ask for more details if not enough provided. I am using OSM road data and have created postgres topology for them. I am now cleaning up the data before exporting it for ...
3
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0answers
284 views

ST_Difference in PostGIS : problem with geometry result (Polygon)

I'm experimenting a result issue using the ST_Difference spatial function in PostGIS. Input : Feature 1 and 2 overlaps each other. Both contains 5 vertices, like a rectangle (4 plus an additional one ...
3
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0answers
460 views

TopologyException issue when doing intersection in Geopandas?

When I do overlay processes like intersection, I mostly get: :TopologyException: found non-noded intersection between LINESTRING (229971 4.39944e+06, 229971 4.39944e+06) and LINESTRING (229971 ...
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0answers
65 views

Intersect a line considering the topological direction

I have a set of lines in postgis, and I want to intersects those lines which only go from point A to point B. And I don't want those lines which go from point B to point A. So, my question is : how I ...
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0answers
234 views

Create PostGIS-Topology (edges, nodes, faces) from a list of edges

I have a large in memory table of edges with the following structure: facenr1, facenr2, x1, y1, x2, y2 x1,y1 to x2,y2 is a line. facenr1 and facenr2 is the facenumber of the left and right face. ...
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305 views

Topological Editing of Two different layers in QGIS

Is there a way to apply topological editing to move vertices between two coincident features that are not in the same layer? For example, if I have a crop land polygon coincident with a soil polygon (...
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176 views

not all OSM polygons downloading in QGIS

I have been trying to download all of the polygons contained within OSM for a particular extent of the city. When I do this through > Vector > OpenStreetMap > Download Data, however, many polygons ...
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243 views

How to avoid topology errors when digitizing a road network?

I am working on a road layer project. For the snapping option I'm using the mode to vertex and segment and tolerance 5 pixels. When zooming in (to the max) I do not notice a gap. But when I use the ...
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800 views

Polygon Layer Cleaning with QGIS

I have a little situation with my data. I have vectorized a raster layer, and now I have some issues with the geometries, as you can see in the picture. Most of errors I have are like this one. ...
3
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314 views

QGIS Topology checker wrong results?

I am trying to understand topology checker results and frankly i dont get it - probably i am doing something wrong. Source - Point layer Target - Polygon layer Must be inside - that is working as ...
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0answers
53 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 ...
2
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0answers
52 views

Model Builder ArcGIS - Export topology errors (Iteration Tool)

I was wondering if there’s any option to iterate export topology errors in ArcGIS model builder. My GDB Topology errors has all topologies within the same Topology dataset but model builder seems not ...
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0answers
60 views

Road overlapping - ModelBuilder

I have a road feature class (in illustrations shown in gray color), each object in the attribute table has a "road_width" field with a numeric value, what width the road is. This feature class has ...
2
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0answers
64 views

Spatial join for adjacent polygons with same attributes

I am working with QGIS 3.4.5. I have a map of soil types (~ 100.000 polygons) and I'm trying to find the best way to make a spatial join with ~5000 point features with several numerical ...
2
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0answers
259 views

Avoid Overlap option not working in QGIS

I am creating polygons in a FGDB layer inside QGIS. I have topology on with advance options and have checked avoid overlap option for that layer. Still, I am getting overlap some times and some times ...
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0answers
420 views

Fixing Topology (Gaps and Overlaps) in QGIS

I am digitizing a new polygon shapefile of property boundaries based on orthoimagery using QGIS Zanzibar. I'm acquainted with topology editing in ArcMap using geodatabases. I did so with snapping to ...
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364 views

Does GeoPackage support topology?

Does GeoPackage support topology? I am looking for resources that discuss this topic in more detail. I googled and did not come across good resources that discuss this question in detail. I could ...
2
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1answer
187 views

Adding vertices to multiple overlapping line segments in QGIS?

I have a polyline dataset of transit routes for my city. Around the transit stations, up to hundreds of routes overlap completely, but do not follow the correct path that the busses actually travel (...
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0answers
70 views

PostGIS Simplification on topogeometry does not respect topology?

I'm testing the code in the book "PostGIS in Action" (2nd ed) on Topology-based Simplification: DROP TABLE IF EXISTS _temp_table; CREATE TABLE _temp_table AS SELECT feat_name, ST_Simplify(topo,150) ...
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552 views

Topology Network in PostGIS database

I'm returning to the same question all over again. I'm dealing with electrical network and I'd like to build topology for all network lines in database so I can construct nodes and edges dynamicly for ...
2
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0answers
754 views

Automating topology error fixing with ArcPy?

I have a web application where folks upload a zipped up file geodatabase, I unzip it and manipulate the feature classes and then transfer them using insert cursors to an SDE database. I am wondering ...
2
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0answers
103 views

Automatically delete overlapping polygons

I have 200 000 polygons that needs to remain like circle and they can't be on top of each other. I need to find a way to correct the 8000 errors I've got automatically. A picture's worth a thousand ...
2
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0answers
145 views

How to simplify line geometry and preserving topology in Oracle?

I have some polylines in an Oracle database which are topologically connected and I want to simplify these lines based on a tolerance directly in Oracle. I need something like ...
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0answers
37 views

Looking for documentation on GRASS vectors/topology

I am looking for documentation (including pictures) of the rationale behind GRASS topology that answers questions like: "What is a topology according to GRASS? How are topologies inferred from ...
2
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1answer
493 views

When does Shapely's “polygonize_full” detect a dangle?

Shapely's polygonize_full operation, which merges line segments into polygons, returns four geometry collections: polygons, dangles, cuts and invalid ring lines. Dangles are defined in the ...
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0answers
223 views

PostGIS topology: creation of topogeometry polygons for simplification

I am using PostGIS topology to manage a geologic mapping project. My basic topology is defined by linework. The interstital polygons are meaningful, but can be constructed simply from lines and ...
2
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0answers
204 views

QGis 2.18 (and other tests on QGis 2.14) hangs with GRASS 7 editing session (OS Windows 8and 10)

I installed QGis 2.18 (64bit and 32bit versions) and i started a session with GRASS 7 in Windows 8 environment (the same thing I did on another workstation with Windows 10). I loaded a test layer with ...
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0answers
174 views

Topology Checking issue in Qgis 2.14.1

I am working on a large data set of Road with snapping tolerance 5px with topological editing option enable. When i am zooming to the snapped vertex with zoom level upto 1:50, its looking snapped or ...
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0answers
288 views

Overlapping despite topological editing

I am digitizing polygons from an ortophoto. In the snapping options, I enabled 'topological editing' and 'avoid intersection' of the polygon layer. I digitized some not-adjacent areas and then made a ...
2
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0answers
162 views

Removing overlap within multipart polygon in ArcGIS for Desktop?

ArcMap 10.1 SP 1 License: Advanced I am attempting to remove overlapping portions of a multipart without going through the steps exporting or creating a layer from each part and clipping individually....
2
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0answers
386 views

TopoGeometry commands with postgres are really slow

After messing around quite a while, I was finally able to get a topogeometry converted from my geometry table following the example of toTopoGeom. I have the topology extension, with a topology schema ...
2
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0answers
260 views

Is there a way to build topology and work with topology relations in PyQGIS?

Is there a way to build topology and work with topology relations in PyQGIS? I'm asking because I need to run some custom generalization algorithms on my data, and I need to preserve topology. ...
2
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0answers
320 views

Is the TIN created out of several cross sections different from merging the TINs created out of each set of two cross sections?

I have a river with cross sections that have the water surface elevation values. I am trying to create TIN from the water surface values and then compare it with the topo (to see the flooded areas). I ...
2
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0answers
478 views

GeoDatabase topology and rules with a *.rul file

I have been working for some time on a solution to a problem much like this question. I have several layers that I want to resolve together. I have them all in topology (geodatabase) and have been ...
2
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0answers
112 views

Topology validate error

Im using Arcmap 10.1 version.I don't know where i made mistake my database. I have attached an example image to show the Error Report.
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0answers
810 views

Snapping line endpoints to a point feature class by adding a vertex

I have a line feature class whose endpoints should snap to the closest point in a points feature class. The problem is, I do not want the lines to move, but rather a vertex must be added to the ...
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102 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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33 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 ...
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51 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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0answers
45 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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0answers
69 views

How do I edit the rules in an already created geodatabase topology in ArcGIS (10.7.1)?

I'm using ArcGIS Desktop 10.7.1 with an Advanced license and created a topology for a file geodatabase I'm working with. (I have complete access to the data.) I'd like to edit the rules that I've ...
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1answer
28 views

Choosing topological rule to have polygons from one feature class be filled, in their entirety, with polygons from multiple feature classes

I am using ArcGIS Pro. I am trying to get polygons from a class to be filled entirely with polygons from multiple other classes. The 'Must Be Covered By Feature Class Of' rule would seem to do fine, ...
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0answers
98 views

How to delete vertex and keep topology

I work with line vector data (road network).The lines (roads) includes several vertexes. I would like to have for each line only nodes - at the end of line, or at the intersection of n lines. How can ...