Topology describes non-metric relationships among geometric figures, such as adjacency, containment, and orientation.
17
votes
2answers
1k 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 ...
16
votes
1answer
863 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 ...
13
votes
1answer
570 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 ...
12
votes
1answer
321 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.
...
12
votes
2answers
718 views
How to generalize a polygon file and maintain topology in QGIS?
my problem: I have a polygon-file in shape-format, which I need to generalize. How can "split" the polygons into lines, generalize and than "rebuild" the polygons, so that I can ensure, that there are ...
10
votes
3answers
565 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 ...
10
votes
2answers
391 views
How do I describe a special relationship between connected edges?
Consider this simple situation where three edges connect at a node:
I’d like to write a succinct and clear description of the relationship between A and B in such a way that differentiates it from ...
9
votes
4answers
2k 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
7answers
865 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 ...
9
votes
3answers
1k 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 ...
8
votes
1answer
152 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?
...
8
votes
8answers
1k views
How to build topology without an ArcEditor or ArcInfo license?
I have a huge dataset that I am capturing that was full of errors previously and I want to make sure that the new version is error free - which can be very time consuming with only an ArcView standard ...
8
votes
2answers
375 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 ...
7
votes
2answers
884 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.
...
7
votes
1answer
389 views
Advanced Polygon and Parcel Splitting
While I am still struggling to divide polygons into same sizes in ArcGIS (we are using ArcView 3.0 scripts now which work fine), I now have an even much more complicated problem:
I would like to ...
7
votes
1answer
1k 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 ...
6
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?
6
votes
3answers
1k 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
1answer
89 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 ...
6
votes
2answers
301 views
How to analyze differences between two shape files and put results into a new shape?
I have two polygon shape files of the same region from two different years (1985 and 1997) and I need to analyse the differences between the two shapes resulting in a third polygon shape file ...
6
votes
1answer
193 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
320 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 ...
6
votes
1answer
155 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.
...
6
votes
1answer
604 views
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.
...
5
votes
2answers
494 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 ...
5
votes
2answers
233 views
Just view topology errors in ArcGIS
I have a basemap (parcels), which is to be used as target for several conflation tasks. This basemap MUST NOT be modified in any way.
The basemap ist part of numerous topology rules. Each time ...
5
votes
1answer
654 views
How to create adjacency matrix of topology graph of arc map for shortest path?
I have created a topology graph of a polygon feature and I want to find the individual FIDS of the lines of the polygon. I want to construct an adjacency matrix to create the shortest path. How can I ...
5
votes
2answers
146 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
votes
3answers
811 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 ...
4
votes
2answers
209 views
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
3answers
541 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 ...
4
votes
1answer
111 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 ...
4
votes
3answers
92 views
Is there a simple tool to split polylines into two-part lines at the vertices in ArcGIS 10.1
Background: I'm using ESRI ArcGIS 10.1 SP1 at my office, Baltimore County Government, and we have a problem. There is a serious topology bug that I've mentioned in another question that is affecting ...
4
votes
1answer
274 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
...
4
votes
2answers
371 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 ...
4
votes
1answer
91 views
Learning resources for beginning differential topology for a programmer?
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 ...
3
votes
1answer
796 views
Intersect two polylines using ArcObjects
I have two polylines and would like to find the intersection(s) using ArcObjects / VB.NET.
I'm using the following code:
Dim topoOp As ITopologicalOperator = TryCast(pTestPoly2, ...
3
votes
3answers
48 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.
...
3
votes
2answers
44 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 ...
3
votes
2answers
175 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
2answers
321 views
Topology error in ArcGIS for SDE 10. “Cannot create topology”
When trying to create a topology for a polygon feature class in ArcSDE. I right click the feature dataset that the feature class resides and try to create a new topology. I get an error saying, "The ...
3
votes
1answer
125 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
2answers
269 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 ...
3
votes
1answer
115 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 ...
3
votes
1answer
112 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
1answer
74 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 ...
3
votes
0answers
45 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.
3
votes
0answers
139 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 ...
3
votes
0answers
182 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 ...
2
votes
2answers
761 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 ...
