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Geographic Information Systems

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.

417 questions
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Find Close Vertices in QGIS

I am trying to find digitizing errors in a line-layer. Obviously the snapping was not activated when the person who digitized created the lines. As far as I know QGIS cannot find undershoots, so I ...
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29 views

What key points defines a GIS? [on hold]

I realise this looks like a very simple uneducated question from the title, but I am drawing up guidelines for 'what makes something a GIS' and I am wanting to check with the community that I have not ...
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1answer
35 views

More customizable topology options for QGIS

I'm working on a polyline network where there are a lot of open-ended lines that I do want, but also a lot that I don't. QGIS's topology checker flags all cases, making it a major hassle to go through ...
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31 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 ...
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1answer
35 views

Finding difference in gaps between polygon

I am using ArcGIS Desktop. I have a feature class of polygons. At first I run topology with rule "must not have gap" error. I find 250 errors (these all are exceptions). After shifting all the ...
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0answers
34 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 ...
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1answer
34 views

Polygons split themselves when I zoom out

I've been having issues with polygons getting deleted and re-created in this layer, and also with polygons not merging the way I would expect. I thought I had everything fixed-- my topology check ...
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1answer
38 views

Remove overlaping vertices in lines - QGIS

I am currently working with data that has a huge amount of topological errors. These are lines that are closed, in the place where the beginning of the line meets the end, someone added more than 2 ...
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1answer
55 views

PostGIS topology hierarchal topogeometries

I'm seeking guidance on how to correctly organise hierarchal topogeometries. I'm working through PostGIS in Action's chapter on topology and, in summary, it sets up two tables with topogeometries, ...
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1answer
60 views

How can I enable topological editing in QGIS 3

How can I enable topological editing (create shared nodes on adjacent polygons or intersecting lines) and also activate the option to prevent polygon overlap (that when a new polygon is drawn, its ...
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1answer
37 views

Connect points to lines so moving points moves line?

I'm trying to create a simple sewage system in ArcMap. I want it so that when I move a node/point, the line is moved as well so it needs to be attached to the point (dynamic link?). A Point may have ...
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Deleted Topology and Feature Classes are still locked within Geodatabase

I deleted my topology within a geodatabase rather than disconnecting the feature classes inside of it. Doing this appeared to have deleted all 4 feature classes that were within the topology entirely ...
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1answer
31 views

ArcGIS Pro Topology - Fix multiple errors in one step through Inspector

Does someone know if it is possible to select multiple "error-features" in ArcGIS Pro Topology error inspector and fix all of them with the same solution (e.g. create new feature)? Currently in ...
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RoadLink and RoadArea topological relation in INSPIRE

I have some confusion about RoadLink and RoadArea topological relation in INSPIRE (Infrastructure for Spatial Information in the European Community). If I got this correctly: RoadLinks are connected ...
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1answer
47 views

Automatic cleaning of polygon overlap based on attribute in QGIS

I have a shapefile with overlapping polygons. I need to clean these overlaps based on an attribute: in case of polygon overlap, the polygon with the lowest value of a given attribute needs to be ...
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0answers
20 views

Checking snapping connection of polylines? [closed]

I would like to find a method using ArcMap that could check if all polyline are snapping and connected. I tried to create road network, but I can see this information. I have multiple polyline, and ...
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2answers
147 views

Checking if vertices of polygon are in clockwise or anti-clockwise direction in QGIS?

Is there a simple way to calculate a field in QGIS indicating if the vertices of each polygon feature in a layer are in clockwise or anti-clockwise direction? For simplicity, lets assume the layer ...
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1answer
30 views

Adding ArcGIS topology rule that allows Attribute based exceptions?

I want to run a topology - one is geometry based where I am looking for overlaps as error, but in my database I want to keep some error as exceptions (such as road over waterbodies). One option is ...
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1answer
39 views

Discerning dwelling types in QGIS? [closed]

In QGIS, I want to discern between a number of building types, based on topology. I have data on buildings, parcels and addresses. I'm having a hard time to discern between row/terrace, end-of-...
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19 views

Detecting bow in lines of file?

We have a file made in CartaLinx that has thousands of polygons manually vectorized. Apparently, some of the lines go over themselves so the file corrupts frequently. Cartalinx can't find the bows ...
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0answers
77 views

How do I select the longest connected lines from PostGIS ST_ApproximateMedialAxis?

I used PostGIS ST_ApproximateMedialAxis to transform polygons representing mountain ranges into a series of lines. Now, I'd like to select only the "longest" line segment for each group, so that I ...
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73 views

How to automate topology check/fix in QGIS?

Short version: I have a layer with 19483 features with plenty of topological errors and I would like to fix/review them as many as possible in an automated way but don't know how to do it. ...
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0answers
27 views

error 999999 add rule to topology management

I was trying to create a topology with some rule, but I have problems with the rule "Must Be Covered By Feature Class Of". I get the error "999999: Error executing function." This is the code: WU =...
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20 views

Cannot Create Topology in SDE

I am trying create a topology for a zoning dataset in my SDE feature dataset. I've run into a few issues. First off was an issue with versioning that this questions resolved: How to solve "Cannot ...
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2answers
34 views

When topological editing how can I automatically snap lines to lines close to them?

Using ArcMap 10.3, advanced license, I have a data set of road lines and another data set of road surface conditions, and I need to apply the road conditions to the road line as an attribute where it ...
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0answers
34 views

QGIS topology check shows different topology check results for same area

I used QGIS topology checker for parcel data of an area in QGIS 2.18. The rule used was- 'Parcel must not have gaps'. The result showed many error (gaps) and while zooming in and zooming out, the ...
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22 views

Arcpy export topology errors bug

I have created an ArcGIS Python script tool that creates and validates a topology dataset, exports the topology errors and performs some analysis between the topology errors and their source feature ...
4
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1answer
67 views

Fixing bad topology on polylines with QGIS

I've been sent a shapefile containing 12 layers of some city's road system. Each layer depicts a portion of the road system, and all of them partially overlap on the map. I'd like to work on the sum ...
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3answers
87 views

Align one polygon boundary to another boundary

As visualized in the picture as an example, two polygons should be aligned to each other. The boundaries of the green polygon should not be changed. The blue polygon may therefore only be adapted to ...
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0answers
31 views

Handling dangling nodes in ArcGIS Desktop?

I have a datafile of line features. The creation of a topology revealed that there are too many dangling nodes to be corrected manually. I was thinking of snapping to the closest line feature in an ...
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0answers
81 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 ...
2
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1answer
115 views

Repairing all topology errors at once in ArcMap?

In 2012 an ArcMap user wrote Automatically fixing multiple errors using Fix topology error tool?: I am a ArcGIS.10. user. I'm want to solve multiple errors using the fix topology error. So I ...
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0answers
87 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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2answers
229 views

Is the erratum about polygon point order in GeoJSON correct?

The GeoJSON specification (RFC 7946) states that for polygons: A linear ring MUST follow the right-hand rule with respect to the area it bounds, i.e., exterior rings are counterclockwise, and holes ...
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26 views

Topology validation problem

I have a problem with a feature class which has a topology problem between two polygones. The problem is when I select an error area and I merge It, the error remains. The two rules that I used are : ...
4
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1answer
257 views

QGIS 3.0.3 topology checker to find gaps between polygons

When using QGIS 2.x I have used Topology checker to find gaps between polygons, crossing lines and duplicated points/vertex. I also liked that it shoved a list of errors where I could zoom into each ...
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0answers
60 views

I can't import or export a topology

I tried to export a topology using the function arcpy.ImportTopology_defense(GDB_input,os.path.join(arcpy.env.scratchGDB,dataset+".xml")) but it throws an error : AttributeError: 'module' object ...
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24 views

topological edits in ArcGIS for Server

I am developping a ServerObjectExtension using ArcObjects to extend an existing map-service. Now I want to perform some edits. There are many featureclasses that have to be handled together. However ...
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96 views

Self-Contact Topology Errors?

I've been trying to clean up some vector data sets so that I can reproject them to WGS84 but I keep finding topological errors that fail the process. The one error I can't resolve involves a node on a ...
3
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1answer
81 views

Editing two layers topologically in QGIS?

I have different polygons in layer a_input. The Polygons are adjacent and connected inside the layers and it should be. The Polygons in layer a_input have to fit adjacent to a polygon of layer 2 ...
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0answers
34 views

Topology checks and error marker

I have a problem in QGIS. I want to find overlapping polygons but not only which polygon overlap with another but the exact node(vertex) that intersect or overlap. The error marker doesn't show you ...
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0answers
27 views

Versioning error when creating a Topology on a File GDB

Im having an issue with the 99999 Error. Im creating a Topology dataset for each of the featureclasses within a GDB. For some reason my script works for some feature classes and errors on others. I ...
0
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1answer
91 views

Identifying road segments completely cut off by polygon using QGIS?

I have a road network (black line) and I want to identify all segments that are completely cut off by my flood polygon (blue polygon). I have clipped the road network to get all roads within the road ...
3
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1answer
98 views

Fixes to achieve topology in QGis not working

I imported a .shp file to QGIS with polygons from a non-topological database. Polygons were adjacent and shared borders, but most nodes didn't coincide. I then proceeded to fix all nodes and ...
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2answers
85 views

Is there a way to save and share topology rules in QGIS?

I would like to create a set of topology rules and use them over and over again. I would also like to be able to share them with my team. Is there a way to do this in QGIS? I'm using QGIS 3.0 but I ...
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0answers
78 views

Creating custom topology check script for QGIS?

In a comment on an answer to Accessing python module for QGIS 3.0 topology checker from Python script? I asked if I could import the topology checker plugin in QGIS in a python script similar to the ...
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0answers
64 views

Invalid Topology: Cannot Open Cache File when trying to do a dissolve

I'm trying to perform a dissolve to take some data that is at the Census Block level to the County level. I'm dissolving by the County ID and doing a Statistic Field for various attributes (1 SUM, 2 ...
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1answer
122 views

Accessing python module for QGIS 3.0 topology checker from Python script?

There is a similar question Access QGIS Topology Checker from Python, however this user was wanting to run the topology tool while I want to import certain rules. For example in arcgis arcpy....
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1answer
39 views

Handling Topology in ArcGIS Online?

Can ArcGIS Online act as a solution for handling topology? For example, if I have a hosted feature service with topology in it, can I maintain the topology in the hosted feature service using tools ...
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1answer
30 views

Loading points and polylines into PostGIS database and creating connectivity between them using topology?

I am new in PostGIS, and I am trying to create connectivity(using topology) between 3 sets of points and polyline to model an electrical distribution network. Does anyone know how to do this?

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