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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799 views

How to clean layers from non topological databases?

I'm doing my internship in a consulting office which is switching from MapInfo to QGIS/GRASS 1.8.0. I posted here a few days ago about the way to clean a polyline from a Lidar data with v.clean. ...
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0answers
274 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 ...
3
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1answer
115 views

Learning resources for beginning differential topology for a programmer? [closed]

With this question I'm looking for suggestions about how and where to start learning differential topology starting from a good base of linear algebra and geometry, also consider that this know-how is ...
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0answers
89 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
4
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2answers
84 views

How to store and edit data with a defined topology using open software and formats?

I'm looking for a way to store and edit spatial data that preserves topological information. In my concrete application, I need to represent triangular meshes, which consist of unique nodes and ...
2
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1answer
531 views

need help for script checking topology using ogr in python

My main goal is to create a new feature indicating if the line features intersect each other as well as if they are not connected to a feature. My problem is how to identify the intersecting and not ...
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3answers
1k views

How can I easily detect gaps in a polyline using arcmap 10.0 (arcview license)?

I'm making routes by selecting links from a streets layer which I export as a new temporarely layer in arcmap 10. This layer which I call route_temp unfortunately can be very long and contain gaps, ...
4
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1answer
605 views

Simplification algorithms for 3D topology

My problem is about simplifying a given topology that can be opened ( an usual 3D reconstruction of a given square on a map ), totally closed (like a perfect sphere) or a topology with holes ( a ...
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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. ...
4
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4answers
689 views

How can I create polygons of the area surrounded by roads / lines?

I'm currently trying to create polygons that represent the areas surrounded by roads. The roads are stored in PostGIS as points / lines so I have flexibility over what I can do with them. I'm ...
9
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1answer
378 views

How to add topology to PostGIS 2.0?

I have installed PostGIS 2.0 and need new topology but it doesn't seem installed by default. I found a lot of command line to install postgis 2.0 with topology but is there a way just to add topology? ...
5
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2answers
2k views

How to solve “Cannot create topology” in ArcCatalog?

I have a FileGeodatabase in ArcGIS 10.0 with a feature dataset and five feature classes (3 polygon shapes, 1 line shape, 1 point shape). I'm trying to create a topology to verify some vectors. ...
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
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0answers
90 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.
4
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1answer
344 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 ...
2
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0answers
418 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 ...
8
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2answers
695 views

How to speed up space partitioning in postgis?

I've a bunch of overlapping polygons and I'm trying to partition the space to avoid having overlapping ones. I think my problem is fairly simple. Using some ESRI product and ...
2
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1answer
148 views

Compiling a list of units that border each other

I have a shapefile of U.S. counties. I am interested in compiling a list of those that border each other. In particular, I am interested in those that border each other but are in different states. ...
5
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1answer
1k views

How you can repair invalid topology errors within postgis?

I've imported the shapefile of corine land cover project to my postgis database and the select gid, ST_IsValidReason(geom) from gis.clc2000 where not ST_IsValid(geom); returns in every occasion ...
2
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1answer
102 views

how to judge the side from a point to a linestring

I'm working with NTS (NetTopologySuite), I get point geometry and a directed linestring, how to judge the side of the point locate with the linestring? one the left side, right side, or just on the ...
4
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2answers
2k views

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 ...
6
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1answer
1k 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 ...
2
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4answers
2k views

How can I create polygon of gaps/holes if I have several shapefiles

How can I create polygon of gaps/holes if I have several shapefiles. Do I really have to merge all layers, it it big amount of data (NEW YORK roadbed, buildings, water,parks etc) I have ET geowizards ...
7
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1answer
242 views

Optimize GEOSGeometry's spatial operations by avoiding thread-safety checks

A ranking algorithm I'm developing for a Django webapp requires performing spatial operations (within, intersections, sym_difference, etc.) using a query against large number of geometry objects. ...
18
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1answer
1k views

What's the status of Postgis 2.0 topology support in QGIS?

Having followed the Postgis developments over the past 6 months I have noticed a bunch of features which seem to be incredibly cool especially in the area of topologies and associating calculations on ...
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1answer
135 views

I need help to find out more information about Topology Errors toolbox or Extension?

I need someone out there who can answer my question. I do not remember if I add this Topology Editor Extension or toolbox to my ArcMap. I would like to know more about this toolbox. Thanks. (Changed ...
0
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1answer
3k views

How to resolve an Invalid Topology [Incomplete void poly] error from a geoprocessing service?

I am consuming a geoprocessing service from my Flex application. My geoprocessing service takes the input geometry, and intersects another layer. It then runs a Summery stats on the intersection ...
2
votes
1answer
695 views

How do I subdivide and edit polygons preserving topology?

I'm using QGIS. I have a layer made up of many adjacent polygons - let's call them "countries". I currently use the Atlas plugin to export each "country" polygon to a .png file. I want to further ...
4
votes
3answers
1k views

Questions on smooth lines on soil polygon?

In a couple of weeks I am going to do QA/QC on soil polygons and I'm wonder if there is a way for me to run a script or a tool box that allow me to find the jagged lines ? Alternative, my plan would ...
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2answers
297 views

Automatically apply topology rule to only selected portions of a .shp file?

I am looking for some examples/tutorials on how to apply a topology rule to only a selected portion of a shp file using a script in ArcGIS/GRASS. Using ArcGIS seems to always require an interactive ...
1
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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 ...
4
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0answers
257 views

Topology - To be, or not to be, that is the question [closed]

Topology, I mean "real" topology, is not a new concept and it's available since a long time in GRASS gis. I won't speculate the reasons myself but, after a long period of spaghetti model ...
8
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1answer
3k views

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 ...
13
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1answer
2k views

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 ...
3
votes
2answers
501 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 ...
7
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2answers
898 views

What does 'building topology' mean for pgRouting?

From a couple of answers at gis.stackexchange.com and at the pgRouting mailing list I have found out that pgRouting 'builds topology'. What does that mean? If for example we import an .osm file into ...
2
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2answers
804 views

Topological relationship between two polygon feature layers

I have two polygon feature layers: one representing land parcels and one representing roads. Some land parcels (polygons) coincide with a part of a road (another polygon feature). How can I check ...
6
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1answer
100 views

Dividing the world space to geographic sub-space

I am trying to divide the world space to geographic sub-space from "general" to "specific" locations and without using latitude and longitude information. That is, I am trying to think about the world ...
5
votes
1answer
815 views

3d polylines and polygons

Is there a way to extract z values from a DEM into a polyline and/or polygon featurclass in arcmap 10? I would like to have 3d polylines and polygons to make cross sections in a CAD, but currently I ...
1
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2answers
341 views

topology of geometries in gis

http://imm.io/2cpJ What is the thinking of OGC to keep this point that "point have no boundry , it just has interior"... what do they mean? this notation: F**F*****...still i am confused due to OGC ...
20
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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 ...
12
votes
4answers
3k 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 ...
9
votes
5answers
1k views

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?