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.

learn more… | top users | synonyms

3
votes
1answer
207 views

T-shaped polygons

Is there any coefficient that can indicate T-shaped polygons ? Examples of T-shaped polygons :
1
vote
0answers
290 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'...
3
votes
1answer
133 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 ...
1
vote
0answers
278 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, ...
2
votes
1answer
291 views

GRASS - v.clean Conflation - How to snap a layer to a base layer

Someone told me in this post that GRASS GIS can handle multilayer topology, what I have not found any information about. I am not a specialist of GRASS GIS so I would need help with that if its really ...
4
votes
1answer
467 views

Topology problems with QGIS/GRASS

*edited file links below I'm working on several NGO projects at the moment, all of which are reliant on being able to use a district level map with some 490+ features, and I am running into some ...
1
vote
0answers
136 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 ...
4
votes
5answers
2k views

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 ...
2
votes
3answers
364 views

How to correct topology on a shared boundary by removing nodes from a feature?

Maybe you can help me solve a problem regarding topology cleanup that I recently came a cross. I have two layers with bunch of polygons (or feature classes as I'm in the ESRI world) that should share ...
0
votes
0answers
54 views

The topology cannot be validated because it is checked out

when I try to validate an existing topologiy in my personal GDB I got this error "the topology cannot be validated because it is checked out". How to solve it? thanks! It is a personal GDB. I'm ...
1
vote
0answers
430 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 ...
4
votes
4answers
696 views

Is there a way to snap to apparent intersections in ArcGIS 10.1+?

Suppose there are two lines in an ArcMap 10.1 or 10.2 editing session that cross but do not intersect, per se. This is the case when new lines a drawn. Is there a way to snap to the point where the ...
2
votes
1answer
294 views

measuring adjacency between polygons

I am working with some land ownership data. I would like to identify parcels the have small adjacency between other parcels. In a nutshell I want to identify where there is a small overlap between ...
1
vote
1answer
211 views

Problem when creating database based on template_postgis

I have created a PostGIS template but when I try to create a database based on this template this is what happens: Connecting to the template: \c template_postgis; You are now connected to database ...
2
votes
0answers
109 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
votes
2answers
1k views

Doubts about how pgRouting topology is built and how flexible it is

I'm learning pgRouting, to validate if it can be used in a project. I have several doubts. Mostly related with how could I "fill the gap" between the "bricks" it provides and the real world ...
1
vote
1answer
975 views

Insert Vertex into Polyline based on Point layer using arcpy

This is essentially the same question asked here that was not answered... Using ArcGIS 10.1 Advanced I have a point layer with points that represent the intersection of a driveway with a street ...
4
votes
2answers
1k views

Is there website with list of common QA/QC errors?

As I am working on reviewing my soils spatial data, and I am doing my QA/QC I placed a point layer to check for errors. I add the field column to mark the error and state the error. I recently ...
1
vote
1answer
158 views

ESRI ArcMap Topology rules on multi story buildings

I would like to run some topology rules to find snapping errors in our polygons but I am running in to the problem where we are working on multi story buildings with every polygon regardless of floor ...
9
votes
2answers
748 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 ...
1
vote
0answers
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-...
6
votes
3answers
5k 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" ...
1
vote
1answer
280 views

ArcView: Trim polyline, that is shorter than specific dangle length (alternative to tool: Trim Line)?

I am looking for a way to trim dangles from a polyline shape, that are shorter than a specific length like the Trim Line Tool for ArcEditor and ArcInfo, but with ArcView-License. I already discover, ...
2
votes
0answers
162 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 ...
14
votes
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?
2
votes
0answers
352 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 ...
3
votes
3answers
273 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 ...
1
vote
0answers
532 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 ...
1
vote
0answers
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 "...
4
votes
5answers
3k views

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 ...
3
votes
1answer
225 views

How can i topologically sort 2D triangles and put in an array?

I have a set of 2D triangles in a Geometry array which together forms a connected strip when placed them according to edge adjacency. However, in the array they are not in topological order based on ...
2
votes
1answer
260 views

Tools/Script to reshape automaticaly topologic edges within a given distance in ArcGis 10?

I have a footprint feature class and a land use cluster feature class. I am looking for a method/tool/script that would allow me: to reshape two edges into one (topologically) to decide at which ...
13
votes
4answers
3k views

How to connect lines in a network?

I have a shapefile of lines and another of polygons. When two or more lines intersect a polygon they should be connected (snapped), but sometimes during manual digitization this doesn't occur. I need ...
1
vote
0answers
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 ...
3
votes
1answer
358 views

SDE Topology dirty areas don't go away

Just looking for an explanation on SDE Topology dirty areas that don't go away. My workflow involves editing a version of SDE data, then once finished I use the Validate Topology in Current Extent ...
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. ...
2
votes
1answer
1k views

Grass v.clean.snap with Polygons

I am doing some topology testing using Grass in QGIS. I am hoping to snap nodes to eliminate gaps between polygons. When I use the v.clean.snap function in Grass it does not work on polygons. When I ...
7
votes
3answers
1k views

Snapping start- and end nodes of lines to other lines in PostGIS

There are plenty examples that show how to snap lines to points, but I haven't been able to find any (fast!) way of snapping the start- and end nodes of line strings to nodes of other lines. ...
4
votes
1answer
894 views

How to repair and clean contours from high data resolution (lidar)?

I'm unsuccessfully trying to make a bathymetric map with contours extracted from Lidar data at 1 m resolution. The extracted contours have a lot of artifacts like dangles and islands. First I used ...
3
votes
3answers
855 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. I'...
1
vote
0answers
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 ...
3
votes
1answer
116 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 ...
1
vote
0answers
90 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
votes
2answers
86 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
votes
1answer
606 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 ...
0
votes
3answers
2k 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
votes
1answer
721 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 ...
12
votes
2answers
8k 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. ...
5
votes
4answers
816 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
votes
1answer
382 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? ...