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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Joining layers with respective elements with PostGIS Topology

I'm currently using PostGIS topology extension, but I have some difficulties in understanding how the structure works: One of the key points is the use of "layer"s: as of what I understand, features ...
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118 views

Create polygon from lines in PostGIS

I'm trying to divide a polygon in smaller polygons from a line, but I think I can't use the st_split function. What I need is to create small polygons inside a big one, using linestring grid. I've ...
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651 views

Remove pseudo nodes in QGIS

I have a shapefile of city streets. I tried to run the Road Graph tool on them but the select box does not populate with the layer. I ran the Topology Checker on the layer and found that there are 2,...
2
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33 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 ...
2
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40 views

How to run QGIS plugin from python script

I would like to access external QGIS plugins through a python script. I have been able to access the built in QGIS processing and vector toolbox, but have been unsuccessful with external plugins such ...
2
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53 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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88 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 ...
2
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131 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. ...
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143 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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111 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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164 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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357 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 ...
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92 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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472 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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49 views

polygon/polyline digitizing techniques for geological data

My current work involves extensive digitising of historic geology data - essentially the creation of new polygons and polylines based on overlain raster and vector layers. This is all done manually ...
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21 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 the same feature? For example, if I have a crop land polygon coincident with a soil polygon ...
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37 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 ...
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41 views

Aligning polygons in ArcGIS for Desktop?

I am using ArcGIS 10.3 for Desktop. I am working on a map that I have divided into 5 zones. I have drawn 5 polygons to represent each zone. I need to align the polygons where the edges meet. I am ...
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37 views

Pg_dijkstra empty results

I am currently working on PgAdmin, and the pgrouting extension, in order to get the length and the path of the shortest path between every LNG terminal over the world (I have them as a table of points)...
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33 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....
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40 views

pgRouting “Can't find Table”

I am using pgRouting version 2.1.0. I am using pgAdmin III. I have created a street network using Anita Graser's guide: https://anitagraser.com/2013/07/06/pgrouting-2-0-for-windows-quick-guide/ But ...
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31 views

qgis snaps to outside instead of boundary

I have polygon layers that I need to be covered by other polygon layers, and many of my inner layers have a vertex on the border of an outer layer or in some cases they share an edge. Both ST_Covers ...
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58 views

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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23 views

Remove inner border and extend dangles to outer border

I'm struggling with a massive file of grids that need borders extend or snapped onto the outer border of the file. I'm looking to batch this process as I'm currently using topology and and tracing ...
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22 views

How to use the TopoViewer in the QGIS DB Manager?

I'm just wondering what the TopoViewer in QGIS is doing. DB Manager (PostGIS) says 'Schema "schemaname" is not registered in topology.topology'. Unfortunately there is no help available and I can't ...
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67 views

Does QGIS support topological editing of lines?

Does QGIS support topological editing of shared vertices between two or more lines? When in editing mode, if I select a vertex at an intersection, it seems that sometimes it will move all lines ...
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51 views

How to check if a point is snapped to a line in QGIS

I have two vector classes, sg_point and sg_line. Any sg_point HAS to be snapped to a sg_line. I should not find errors if I use snapping correctly, but in case there are errors how do I check in QGIS? ...
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61 views

ArcGIS: Is there any way to use topology on data in different feature datasets?

I am using ArcGIS 10.2 desktop on an SDE/versioned environment. We use the ESRI local government information model, except that we do not use parcel fabric. I am responsible for maintaining several ...
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119 views

Problems using GRASS tools for topology validation in QGIS

I'm working with a shapefile of Enumeration Districts (Setores Censitários) of the 2010 Brazilian Census. Enumeration Districts (ED) are smallest areas for which Brazilian Census data is available. ...
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78 views

how to create Topology table?

i have gis database called Madar in pgadmin with postgis and pgrouting extension, all the data inside gis database already inserted by shp2postgre tool , what i really need now is how to make topology ...
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264 views

Removing pseudo-nodes using QGIS Sextante plugin?

I have a road network (vector) that i'm interested in carrying out some space syntax analysis on. Predictably my GIS data is in a pretty terrible state. For example, there are a bunch of roads on the ...
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163 views

Metric maps vs topological maps for path finding and UI rendering of indoor floor layouts

I'm building a software to map indoor floor plans of large facilities (like malls). I read through some of the questions on this forum, but my constraints are a little different than the ones ...
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1k views

Intersection postgis TopologyException

I'm trying to make a quite simple analysis in Postgis, but I'm finding some problems. I want to in the first place create buffers for then, intersects themselves but one, this will be differenced. ...
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105 views

ArcGIS planarize vs autofixing “must not intersect or touch interior” topology

trying to fix topology errors in OSM here. I am wondering whether ArcGIS planarize is essentially the same as creating a topology that says a class must not intersect or touch interior. Then ...
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113 views

vb.net arcobjects validate topology function only works after I use arcmap topology tool validate topology first

I find a strange thing occasionally, I have a validate topology function developed by vb.net arcobjects. It work not properly. The case is: open arcmap start editing use my validate topology ...
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41 views

How can I associate a consistent polygon area with a set of attributes using a topology?

Consider the following topology. SELECT CreateTopology('topotestschema', 0, 0.01); CREATE TABLE topotest (id SERIAL PRIMARY KEY, data TEXT); SELECT AddTopoGeometryColumn('topotestschema', 'public', '...
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40 views

vb.net arcobjects “current no topology available”

I am using ArcMap add-in to perform a topology validation. I have defined a topology in the geodatabase and add it in ArcMap TOC. When I try to get the current topology using ArcObjects, I get this ...
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189 views

v.clean in QGIS Python console

I have tried to use v.clean and v.clean.advanced (by GRASS GIS) within a script in QGIS, and was not able. I followed instructions here:, but was not able to do so. I got message: "No module named ...
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106 views

Batch Clip (Editing Session)

I'm trying to correct some topology errors in my geodatabase, now focusing on two feature classes: grass and buildings. They must not overlap. However, there are plenty of spaces where the grass was ...
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294 views

How to simplify a self intersected / self overlapped polyline using ArcObjects?

I have a self intersected polyline, how can I break it into 5 records stored in the same table using arcobjects? (splited by vertices and the intersection point) Here is what I have got and it doesn'...
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284 views

How can I edit spatial data automatically on postgis and check for topology errors on said data whitout using shapefiles?

So, I have spatial data stored in postgis (points, lines and polygons) and would like to edit and update those in an Open Source software (quantum GIS, grass, etc.) to check for topologic errors, ...
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138 views

Dissolve a Geometric Network in ArcGIS

I have a geometric network of water mains in ArcGIS. It it composed of a line feature class. I would like to dissolve it based on whether line segments share common endpoints only. So basically ...
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435 views

Vertex and Nodes Tool - Migrating from 9.3.1 to 10.2.1

A previous employee built a custom tool for users in our organization that displays nodes and vertices when editing. Essentially the purpose is: The Display Topology Nodes button will symbolize the ...
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63 views

Delete polygon underlap?

I am editing a layer in QGIS with severe polygon overlaps. Is there a way to delete the underlapping portions (i.e. the invisible parts) using QGIS? If I import the layer into GRASS using the GRASS-...
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54 views

QGIS : copy/paste with “Avoid Intersection” option

I need to copy and paste polygons from one layer to another but with adjustments in the pasted geometries: I need them to be cut in the same way they would have been cut by a single edit with the "...
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91 views

How do you split a feature using an existing line in QGIS?

All, Is there a way to split a feature (polygon) using an existing line (selected polyline) in QGIS? Thanks! -m
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547 views

How to handle/ avoid intersect errors when clipping the difference between two layers?

Using QGIS + Grass, I've added a shapefile of coastline and islands to my map. I then buffer this shapefile to create a coastal zone of a known width. At this stage the buffer consists of the ...
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103 views

From classified image to topology in ArcInfo

I have some coastal 4 band imagery that I have classified to designate land, water, and undetermined. I want to convert this to polygons with topology, and significantly simplify the polygons. If I ...
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277 views

topology rules for structuring topology data to get line feature as topoparent in topology graph

i Created topology graph of a polygon feature and i copied geometry of topology edges into line feature class,and topology nodes into point feature class i created topology layer containing ...
0
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31 views

How to move points in a polygons when editing/adjusting the polygon

I am using QGIS 2.14.3 and I am editing a few polygons in a layer, however in another layer I have some points (one or two points overlapping each polygon). Is there a way to move the points ...