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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Generalizing polygon file while maintaining topology in QGIS?

I have a polygon Shapefile, which I need to generalize. How can I generalize the poligons and ensure that there are no topological errors like "slivers". I already tried: Vector -> Geometry Tools ...
12
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2answers
7k views

How to check Topology in QGIS?

I have two Shapefiles with Polygons ( City and Forerst) Is there a Plugin who is able check the topology (QGIS)? Like "Knots do not overlap" or something like that? I dont want that they overlap. ...
9
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2answers
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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 ...
3
votes
2answers
858 views

How do you remove isolated roads from a bigger network?

I'm trying to perform an OD Cost Matrix calculation on a set of points using a road network from OpenStreetMap data. The network contains lots of roads that don't connect to the rest of the network. ...
14
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5answers
2k views

Find pseudo nodes in free GIS software

Software gvSIG OA Digital Edition 2010 have tools topology for finding pseudo nodes in linear geometry. I set cluster tolerance 0.00002 and maximum number of errors -10000 for 20000 link count linear ...
7
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2answers
5k views

I would like to know how to clean topological errors

I am a new QGIS 2.0 user. I was so impressed the new default tool, Topology Checker, in this new version. But, hundreds errors are bothering me for cleaning up features. Is it possible to clean ...
9
votes
5answers
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How to convert line simple features to topological network?

using Gdal/ OGR is there a way to convert a shp, kml, or PostGIS line layer into a network of nodes and segments so it can be used in packages such as networkx?
7
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3answers
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Analyzing differences between two shapefiles to put results into new shapefile?

I have two polygon shapefiles of the same region from two different years (1985 and 1997) and I need to analyse the differences between the two shapefiles resulting in a third polygon shapefile ...
6
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1answer
341 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 ...
4
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5answers
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How to select all dangling polyline features with Arcview license?

I have a city roads shp file and would like to identify (select) all the locations where a roads ends (in other words dangles). I am working in ArcView 10. I do not want to use a topological tool ...
12
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4answers
4k views

Remove Duplicate Polygons Using Open Source Tools

I have a shapefile containing features with duplicate geometries, but different attributes (e.g. a polygon with attribute XX, and an identical polygon with attribute XY). I want to identify the ...
6
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3answers
4k views

How to fill a hole in a multi-polygon layer on QGIS 2?

I need to fill a hole in a multi-polygon layer on QGIS 2.0. I've set the snapping option for the layer as follows : mode: to vertex and segment tolerance 4 pixels avoid intersection "enabled" ...
6
votes
2answers
8k views

How to repair topology of a shapefile?

I performed an object-based image analysis using ENVI EX, and each of the classified features were exported as a shapefile. I transferred those shapefiles into ArcMap 10, and tried to intersect them ...
3
votes
1answer
882 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. ...
4
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2answers
1k views

How to find self-intersecting polylines using ArcObjects?

If I have a polyline, how do I figure out whether it is self-intersecting? I tried to use ITopologicalOperator.IsSimple Property, but it always returns true. Are there any ways of doing these kind ...
3
votes
1answer
178 views

How to remove spikes in Polygons with PostGIS

I'm trying to validate the topology of a shapefile. I managed to repair cases of overlap and gaps, but i can't resolve cases of spikes. The image shows one example of this situation. I used the ...
14
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1answer
2k views

What is topojson and how is it different than geojson?

This is a conceptual question. What are the differences between these? and what are the pros and cons of these formats?
13
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1answer
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Identifying topological relationships using PostGIS

I'm trying to perform a basic typology analysis using PostGIS. My objective is to find any polygons that touch other polygons. To do this, I thought the ST_GetFaceEdges would work (reference). I want ...
12
votes
5answers
2k 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 ...
21
votes
2answers
2k views

What are the benefits of Multipart Features?

Multipart points, lines, and polygons are implemented in nearly every GIS, but what benefits, if any, do they provide? In a relational database attributes shared by different features can be stored ...
15
votes
2answers
2k views

How to generalize SpatialPolygons and conserving topology in R?

I would like to generalize a SpatialPolygonsDataFrame in R to make plotting more efficient. The polygons I have result in huge pdf plots that are slow to load and hard to integrate into a document. ...
9
votes
2answers
740 views

Are there Desktop GIS alternatives to ArcGIS 10.X for topology and vector conflation?

Is there any options other than ArcGIS for Desktop for topological rules and automatic topology integrity enforcing in a Desktop GIS? I am looking for something that will automatically snap features ...
4
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2answers
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Snapping two polygons together

I have a problem with two vector layers, both polygons. I have been digitising an historical map which contains large areas called townlands, filled by smaller areas called fields. I digitised both as ...
9
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2answers
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How to preserve topology while editing polygons in OpenLayers?

I’m facing this issue: I have a chloropleth map based on a set of polygons with some data. Using WFS-T (postgis, geoserver, openlayers) I am able to edit the geometry of the polygons. This works fine. ...
8
votes
1answer
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Ring Self-Intersections in PostGIS

This is a follow on from previous question. You will see I am a new PostGIS user. I have looked at the validity of the topology in my data and find around 1700 topology issues in the landcover ...
7
votes
3answers
3k views

Create features from ArcGIS Topology errors

I have imported field users shapefiles into an ESRI geodatabase so that I can create some topology rulesets that identifies the errors as needed. Unfortunately the field users do not have a license ...
6
votes
4answers
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What's the difference between hypsography and topography?

I've recently come across some data that has been labeled "hypsography". I looked it up and it sounds like topography. But this data source has data labeled "topography" separate from its ...
4
votes
1answer
306 views

Is there a standard st_relation_readable() function for translate DE-9IM strings?

Spatial databases, such as PostGIS, implement the DE-9IM model with function st_relate(), which returns a string with domain of {0,1,2,F}, meaning 0=point, 1=line, 2=area, and F="empty set"... See ...
3
votes
3answers
271 views

How to identify misaligned corners in PLSS sections

Sometimes PLSS section corners do not align How could I automate the detection of these corners and generate a new shapefile showing where this occurs? I have a shapefile of 147k section polygons ...
7
votes
1answer
565 views

Algorithm to fill the gaps adjacent to parcels

I would like to find a way to fill the gaps between the road and its surrounding parcels, like described in picture below: I have different parcels like A and B , i want to fill the gaps by adding ...
6
votes
1answer
2k views

FME - Can I write back into my original file geodatabase

I have a gas pipeline network which I have stored in an File Geodatabase as polylines. I've created an FME workspace to split the pipelines at fittings (valves, reducers, tees, etc) which are stored ...
4
votes
5answers
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How to Identify and Delete duplicate vertices?

I am trying to figure out how to delete duplicate vertices. I have successfully determined that there are duplicate vertices using PLTS Data Reviewer, but I am confounded as to how I identify and ...
4
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2answers
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How can I identify gaps in polylines and polylines with more than one end point using ArcGIS 10?

I have a multipart polyline shapefile containing a large number of lines, some of which are broken by gaps and some of which have more than one start and end (by mistake - see attached). I need to ...
4
votes
1answer
352 views

Splitting polygons leaves null values

I'm trying to split polygons with overlaping line features, using Split Polygons tool from Topology toolbar. The problem I encounter is that only one from new polygons have old attributes and others ...
3
votes
3answers
1k 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, ...
3
votes
2answers
510 views

Determine point relation to given line

In ArcGIS engine I have a polyline with From and To points. I also have a Point. How can I determine if the point is located on the right or left of the line on the plane considering the direction of ...
3
votes
2answers
321 views

Getting line FID from polygon ITopologyGraph

I want to export polygon Arc list to txt file for that I created topologygraph for personal geodatabase feature class (polygon) using ITopologyGraph::build. I got polygon FIDs but I am not getting ...
2
votes
1answer
166 views

How to correct topology area boundary errors (slivers/gaps) on arcs in arcgis / arcsde

I use arcgis 10.1 (arcinfo licence) with arcsde to connect to a SQL Server database. The initial dataset has around 100k polygons (used for land registration, having a resolution that is around 1cm ...
2
votes
1answer
166 views

Editing polygons simultaneously in ArcMap?

I have two polygons: How can I reshape both Polygon 1 and Polygon 2 at the same time? Will the area of each polygon change automatically in the table after reshaping? I'm using ArcMap 10.1.
2
votes
1answer
1k views

What am I doing wrong with QGIS v.clean?

I thought I understood how the GRASS v.clean tool worked in QGIS (in 2.6.1 Brighton) but I keep getting unexpected results and errors with a polygon ShapeFile. I've run the QGIS TopologyChecker with ...
2
votes
1answer
288 views

ArcMap remove feature-class from feature-dataset

I am using ArcMap 10.0 (Editor). I have got a feature-dataset within a GDB with several feature-classes and an topology. I am unable to find a way to delete/remove a feature class from that ...
2
votes
1answer
2k 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 ...
2
votes
1answer
562 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 ...
2
votes
1answer
1k 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 ...
2
votes
2answers
1k views

Dissolve polygons - group to others with touching corners

I am working with some data that shows land management. There are many places where corners "touch". I would like to dissolve my dataset so that features are grouped (dissolved) with those that they ...
2
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1answer
2k 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 ...
1
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1answer
80 views

Orphan road segments

I am working with OSM road data for a developing nation. Included in the dataset are various small networks of roads that are orphans or islands i.e. not connected to the main road network. For ...
1
vote
2answers
146 views

Topological errors after dissolve - how to avoid/get rid of?

After dissolving a layer in QGIS 2.8, I get a lot of topological errors in the new (dissolved) layer. Any suggestions as to how to get rid of these errors without manually editing each one? ...
1
vote
1answer
6k views

Remove Holes Existing Within a Single Polygon in ArcGIS 10

I have a shapefile that consists of a single polygon. I have gaps within the polygon that need to be eliminated. The resultant dataset shoulde be a single, solid polygon. I have tried implementing ...
1
vote
2answers
1k views

Arc node topology in ArcMap

I would like to implement an arc node topology in arcmap. Do you know how can i build node topology from line layer in ArcMap 9.3.1?