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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Difference 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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25 views

Prevent PostGIS Topology from splitting edges on line insert

I'm dealing with a large amount of road data represented with PostGIS Topology types. Anytime I add an edge over another edge, the edge is automatically split and a new node is created at the ...
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1answer
120 views

Suitable algorithms for simplifying isochrone polygons

I'm looking for an algorithm for simplifying isochrones which were generated using OSM data. These are generally characterised as having lots of small "holes" mostly due to missing OSM data but also ...
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1answer
101 views

What controls the direction of TopoGeometry Linestrings?

In PostGIS, what if anything controls the direction that topogeometry LINESTRINGs will have when converted to geometry? It doesn't appear to be the order in which the edges are listed in the call to ...
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5 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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1answer
56 views

Gaps and overlaps appear after cutting a previously topologically clean shapefile?

I'm using QGIS 2.2 and I have a polygon shapefile which was created by someone else. I have managed to get the shapefile to a topologically clean state by running v.clean but when I tried to cut the ...
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4answers
1k views

Efficiently finding the 1st order neighbors of 200k polygons

For every one of the 208,781 Census block groups, I'd like to retrieve the FIPS IDs of all of its 1st order neighbors. I have all the TIGER boundaries downloaded and merged into a single 1GB ...
3
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1answer
60 views

QGIS Topology Checker select errors

I have used the Topology Checker plugin in QGIS to create rules to identify errors in my layer. For example, I have used it to search for all overlapping polygons. This plugin is great for finding ...
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1answer
64 views

QGIS - Identify overlapping polygons in single layer

I have a shapefile of buffered points in QGIS. I need to display all buffer polygons in this layer which overlap. I have experimented with the intersect tool, but this only seems to work if I am ...
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1answer
86 views

How to interact with GRASS GIS vector map topology “level/layers” from terminal/command line?

Is there anybody out there that can maybe assist in the most simplest form of code to call on command line to "export topology" (which is level 2 information in GRASS) as separate spatial data, as ...
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1answer
29 views

Is there a a way to add a topology dataset to an mxd with arcpy?

I have a script that identifies certain layers from a folder containing several geodatabases. Part of the scripts purposes, or intended purpose is to have it add a topology dataset to the dataframe. ...
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1answer
32 views

Delete all data from a PostGIS topology

I need to delete everything (faces, nodes, edges, anything I'm not thinking of) from a PostGIS topology, but I want to keep my database schema (schemas, tables, columns, sequences, etc.) intact. Is ...
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37 views

How to find points present in one layer but not in a second layer, using ArcGIS?

I have two layers, A and B, with B consisting of a proper subset of the points in A. How can I produce a third layer, C, consisting of just those points found in A but not in B. In R, I would just ...
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1answer
47 views

OSM Data 'gid' column

Eventually I came to know that in order to use pgr_createTopology function to create topology network on my imported OSM data (using pg_routing and postgis on postgresql), apart from the_geom geometry ...
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3answers
141 views

X,Y Tolerance vs. Cluster Tolerance

I can set a "X,Y tolerance" or use default when I create a new feature class. I can set a "X,Y tolerance" or use default when I create a new feature dataset. I can set a "Cluster tolerance" or use ...
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2answers
33 views

vb.net arcobjects determine whether arcmap is in editing session

I have a vb.net arcmap addin which provide a function to validate geodb topology. But there is a problem, when I am not in editing session and use the function, arcmap will crash. In this case I ...
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0answers
91 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 ...
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1answer
1k views

How to populate From Node and To Node fields for a polyline feature class? (ArcGIS 10)

I need to populate FNODE and TNODE fields for my roads dataset. I have an intersections point feature class that has unique ids, and I need each road segment to have an FNODE and TNODE value that ...
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28 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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1answer
29 views

vb.net arcobjects check if topology has error

I follow the esri example for validating topology, is it possible to tell whether topology error exists? The code I use: ' Step 1 - access a topology Dim topoUiD As UID = New UIDClass ...
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1answer
30 views

arcsde topology register issue

I am in trouble with the topology in a sde database. I create a topology in a dataset from arccatalog, after managing to register it as aversion, I try to validate it from arccatalog, it tells me ...
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0answers
23 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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1answer
38 views

Using topology to connect nodes <100m apart only

I have a bunch of line segments, most of which have gaps that are 100m or less. What I'm trying to do is connect these gaps so I have a series of connected line segments BUT leave nodes that are over ...
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1answer
29 views

Working with topology errors sample code error

I am following the sample code from ESRI for checking topology errors using vb.net. But in my workspace an error happened. My code is listed below: ' Step 1 - access a topology Dim topoUiD As ...
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1answer
137 views

ArcMap topology toolbar validate topology button is disabled?

I find a strange thing when I try to use validate topology button. Most of the buttons on topology toolbar are disabled. Last month when I was using a trial license of ArcGIS, I can use these ...
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3answers
505 views

Create a network topology for pgrouting with grade separation

I have built a network using Ordnance Survey's ITN data and I can solve routes across the network. What I need is to build in grade separation topology for overpasses and underpasses on the network so ...
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3answers
138 views

How to set the tolerance value in pgr_createTopology function of pgrouting?

I am making a map based on the floor plan of a building. I made the shapefile and added it to the PostgreSQL database. I created the topology for the map using the following code: SELECT ...
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1answer
49 views

Access a topology sample code runtime error when define ITopologyExtension

I encountered a runtime error when I used the sample code from ESRI on Accessing a topology. The sample code is as follows: Dim topoUiD As UID = New UIDClass topoUiD.Value = ...
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1answer
115 views

How to generate pgrouting source and target with OSM?

Is there anyone here can explain me more details for pgrouting's source and target? I'm wondering how to generate with the given lonlat in OSM PostGIS entities. In pgrouting's website, they are ...
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0answers
23 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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0answers
27 views

Can arcobjects validate topology globally

I want to develop a function which allow user to validate a topology in the whole map wide. But from what I searching from internet, to validate a topology, a dirty area (polygon) must be defined, ...
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1answer
31 views

vb.net arcobjects validate topology ITopologyExtension and esriTEEventHint not declared

I am trying to use arcobjects with vb.net to validate a topology (already defined). I am caught even when I use the sample provided by ESRI. The code I use for accessing a topology is: Dim topoUiD ...
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114 views

What does pgr_createTopology() expect for a table parameter?

In this sample http://docs.pgrouting.org/2.0/en/doc/src/developer/sampledata.html#sampledata there is this function: SELECT pgr_createTopology('edge_table',0.001); I understand that this creates a ...
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2answers
87 views

Software to detect intersections (within a tolerance) between 3d polylines

Is there any way to detect intersections (within a tolerance) for a 3d set of polylines? ArcGIS Topology Check seems to project everything into 2d (x-y plane) before checking, so shows a lot of false ...
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0answers
35 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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2answers
579 views

topology problem

Can anyone tell me how to fix an error after running the topology rule in ArcGIS? I tried to subtract and create a new layer, but a failed warning appears every time.
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1answer
67 views

PostGIS: Update child geometries based on parent

I'm using Leaflet and postgis in a case where using Leaflet draw plugin I draw a polygon first like this Now, I draw a line which cuts the polygon and using line and polygon geometry, based on ...
3
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1answer
704 views

Converting ArcGIS topology rules file (*.rul) to *.txt, *.csv or *.xls for reviewing?

Has anyone converted ESRI's topology rules file (.rul) into another format? I built a complex topology rules set and would like to QC it in something easier to read and work with than ArcCatalog. ...
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7answers
2k views

How to identify polygons with “flag” sliver errors

Working in ArcMap, I have come across errors in a polygon layer that I will call "flag slivers" (taken from similar language in parcels call "flag lots"). These sliver polygons (see image below) are ...
2
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1answer
56 views

Spike finder in PostGIS

I tried to modify spikeRemover from Schmidt & Krüger. My goal it's to obtain, for each polygon, the position of the spikes. I don't need to remove it. For some reason, that I can't figure out, my ...
8
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2answers
5k views

Why Intersect gives ERROR 999999: Error executing function Invalid Topology [Too many lineseg endpoints]?

I am trying to run an Intersect process in arcgis 10 sp 3 with 2 file sets (aspect and slope) from up to a 1m DEM across an area of 65,000sq km. The aspect has 9,930,384 records and the slope has ...
2
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1answer
192 views

What is a pseudonode?

I have been asked to check for pseudonodes - none are allowed for streams but they are for roads. I can't figure out why so I assume I am not understanding what a pseudonode is. I thought it was a ...
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1answer
32 views

In ArcGIS 10 - how do I clip an arc

I have an arc that has violated the topology rule that the road feature should not extent outside of my boundary. I tried to use the clip tool in editor but cannot complete the clip. I should be able ...
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1answer
78 views

Locating 0-points multipart polygons using arcpy

By Running this piece of code: import arcpy arcpy.env.workspace = "C:\working\GEODATABASES\\tests.gdb" fcList = arcpy.ListFeatureClasses() for fc in fcList: with arcpy.da.SearchCursor(fc, ...
3
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3answers
782 views

Cause of selected [ArcSDE 10] feature dataset does not contain any feature classes which can participate in topology?

When trying to create a topology for a polygon feature class in ArcSDE 10. I right click the feature dataset that the feature class resides and try to create a new topology. I get an error saying, ...
8
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1answer
1k views

Splitting landcover polygons (parcels) into equal sizes, while retaining road access for all?

I would like to split landcover polygons which surround a road polygon into equal sizes, while ALL resulting polygons should have access to the road! Is there any chance to do this automatically? ...
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1answer
47 views

check and validate the topology relationship between 2 feature class by concurrent users

my reqirement is allow several users to edit the map and validate the topology relationship between 2 feature class. Michael mentioned in my previous questions that I can only validata a topology when ...
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1answer
41 views

arcpy to handle topology error inspector

I am now want to do topology check use python, but I don't know whether arcpy can realize the function in error inspector. May I call error inspector and get the error records(something like attribute ...
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1answer
80 views

Can I validate topology using python script when ArcMap is open?

I am testing on validating topology using python.The situation is when I run the script when arcmap is open, an error occurs which indicates the topology has already been opened (FDO error: ...
2
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1answer
177 views

How can I make the topology checker plugin ignore very tiny errors?

I'm a QGIS2.0 user. Topology checkers is a very valuable for me as a data creator. I use this plugin for checking data quality. But, this plugin finds too much errors include very, very tiny ...