Tagged Questions

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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3
votes
0answers
22 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 ...
0
votes
0answers
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 ...
3
votes
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 ...
5
votes
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 ...
3
votes
1answer
55 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 ...
1
vote
1answer
61 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 ...
0
votes
1answer
29 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 ...
2
votes
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. ...
1
vote
1answer
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 ...
0
votes
1answer
46 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 ...
1
vote
1answer
84 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 ...
2
votes
3answers
139 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 ...
2
votes
2answers
31 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 ...
2
votes
0answers
84 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 ...
1
vote
0answers
27 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 ...
0
votes
1answer
28 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 ...
0
votes
1answer
29 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 ...
1
vote
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', ...
1
vote
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 ...
1
vote
1answer
28 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 ...
0
votes
1answer
122 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 ...
2
votes
1answer
104 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 ...
1
vote
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 ...
1
vote
1answer
47 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 = ...
0
votes
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, ...
0
votes
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 ...
1
vote
2answers
86 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 ...
0
votes
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 ...
1
vote
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 ...
6
votes
1answer
117 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 ...
2
votes
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 ...
1
vote
1answer
31 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 ...
2
votes
1answer
185 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 ...
1
vote
1answer
77 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, ...
-1
votes
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 ...
0
votes
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 ...
0
votes
1answer
79 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: ...
0
votes
1answer
71 views

Where can I find topology-related algorithms used in QGIS?

I have shapefile with polygons and I test topology - overlaps, duplicates and gaps. I tested it in QGIS and now I have to describe algorithms, which uses QGIS for this rules. I must write research ...
4
votes
1answer
174 views

PostGIS table to network analysis

I use PostGIS 2.0 and Python API (GeoAlchemy) to work with it. I want to convert topological informations (points, lines, faces) from PostGIS tables to topological network (points, lines) to study it ...
0
votes
1answer
81 views

Adding Rules to Topology with Arcpy: getting ERROR 000714

I want to make a very basic python script, however I keep running into error 000714 (general/unknown script error). The topology is created, the features are added to it, however the rule is not. ...
5
votes
1answer
170 views

Is there Open Source equivalent to ArcGIS Integrate (for topology correction)?

I need to transform a set of polygons so that it forms an exact spatial partition/tesselation (no gap - no overlap). What are the existing open-source solutions (software or library) to perform this ...
0
votes
0answers
18 views

Point in Linefeature build through specific topology rules

i want to build Lines from Point Features following different topology rules (that lines aren't like randomly build, but how i should be following the extent from other polygons for example.. when ...
1
vote
0answers
58 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 ...
1
vote
1answer
45 views

How to edit line and polygon layers at the same time?

I have two layers, lines and polygons. Lines are basically the boundaries of the polygons. Is there any way that when I change or reshape the lines the polygons get updated automatically? I normally ...
1
vote
3answers
136 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 ...
3
votes
1answer
95 views

T-shaped polygons

Is there any coefficient that can indicate T-shaped polygons ? Examples of T-shaped polygons :
1
vote
0answers
141 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 ...
1
vote
0answers
79 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, ...
3
votes
1answer
79 views

Verifying the number of times a line crosses other lines

I have a series of lines that represent streams. I have a stream line and two flowpath lines in one feature class and two banklines in another feature class. Total of five lines. I then have a feature ...
0
votes
0answers
48 views

Topology rules for a 3d network

I am currently writing a spec to which people may end up using to guide the digitization of a large 3d network (exterior pedestrian network + building interiors). In 2d network drawing, it seems to ...