# Questions tagged [voronoi-thiessen]

Thiessen polygons are polygons (generated from a set of points) whose boundaries define the area that is closest to each point relative to all other points. Thiessen polygons are mathematically defined by the perpendicular bisectors of the lines between all points and are created by means of a triangulated irregular network (TIN) structure.

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### Fixing non-noded intersection problem using PostGIS

I'm using a PL/R function and PostGIS to generate voronoi polygons around a set of points. The function that I am using is defined here. When I use this function on a particular dataset I get the ...
36k views

### Converting point sets to polygon boundaries?

I'm trying to convert sets of points to their respective polygon boundaries. I think this is something like a Voronoi diagram or Convex Hull, but not quite. I'm sure there's a technical term for it, ...
12k views

### Is it possible to create Thiessen polygons around nodes in QGIS?

Is it possible to create Thiessen polygons around nodes in QGIS? e.g. http://en.wikipedia.org/wiki/Voronoi_diagram
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### Voronoi polygons that run out to infinity?

I have been working on implementing the voronoi.py script (Bill Simon's translation of Steve Fortune's code). According to the QGIS link it is basically the same code that I am working with, but the ...
3k views

### What does buffer mean in QGIS Voronoi dialog?

Could you explain what "buffer" does in the Voronoi dialog i.e. what does the number stand for?
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### How to use ST_DelaunayTriangles to construct a Voronoi diagram?

(edit 2019) ST_VoronoiPolygons available since PostGIS v2.3! With PostGIS 2.1+ we can use ST_DelaunayTriangles() to generate a Delaunay triangulation, that is a dual graph of its Voronoi diagram, and,...
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### Create voronoi diagram from line segments

I'm looking for a way to create a voronoi diagram based on line segments instead of points. See the example below (taken from this presentation). Ideally I'd like something I can script from Python, ...
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### What is the difference between Create Thiessen Polygons tool (ArcGIS) and Voronoi Polygons tool (QGIS)?

Is Thiessen polygons the same thing as Voronoi polygons? I am using ArcMap 10 and also QGIS 2.4 and I would like please to know the exact difference (If any) between the two methods.
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### Constructing Voronoi diagram in PostGIS

I'm trying to construct voronoi diagram from grid of points using modified code from here. This is SQL query after my modifications: DROP TABLE IF EXISTS example.voronoi; WITH -- Sample set of ...
1k views

### Create mosaic like Voronoi Diagram from disjoint polygons

The illustration below shows the problem: as in (a) I have a set of disjoint polygons, as geometries in PostGIS. I need something like (b), the "mosaic" of this set of polygons, building it by a "...
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### Considering holes/constraints in Voronoi polygon creation in QGIS?

I am trying to create voronoi polygons in QGIS that would consider "holes" in the general domain. An example would be: I actually created the Voronois in this image using QGIS through the GRASS ...
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### How to do Manhattan Voronoi on QGIS?

I've spending last two weeks trying to discover how to do a Manhattan Voronoi on QGIS. For the difference between Manhattan Voronoi and "normal" Euclidean Voronoi, please check this link Can someone ...
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### Is there a described GIS method for creating catchment areas based on nearest driving distance?

ie. a combination of Voronoi polygons with isochrones, so that the Voronoi polygons are based on driving distance instead of Euclidean distance. Is there a name or a described method for this?
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### Constructing a Voronoi diagram using a complicated travel time metric

I have in my possession four sets of shapefiles: 1. Locations (points), around 1000 2. Roads (lines), each road has a speed attribute 3. Terrain (polygons), each zone also has a speed attribute 4. ...
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### Voronoi Diagram on a given polygon using QGIS

I am trying to create a Voronoi Diagram on a specific polygon, but there is some issue when dealing with edges. Here is how I do it: Preparing the points for Voronoi and the polygon for the diagram ...
580 views

### Voronoi that don't cross boundaries

I have several dozen points plotted across the UK. Each point represents a facility that serves local people. To estimate the catchment areas of each facility I created Voronoi polygons around them, ...
629 views

### Constrained Voronoi polygons QGIS

I have a shapefile of polygons, which are effectively borders of a geographic unit (consider as an example the 50 u.s. states, each state has within it some number of points.). I'd like to create ...
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### Obtain voronoi polygons which extend till the boundary of another polygon

I have certain hubs (coloured yellow) in a district (coloured light blue). I need to find polygons indicating the closest hub to every point in the district. The voronoi polygons that I obtained ...
838 views

### How to grid unevenly sampled categorical data?

I am looking for a method for gridding categorical data. I have extracted from nautical charts and field sheets a collection of points specifying the nature of the surface of the bottom of the ocean. ...
6k views

### R function for Thiessen Polygons

For a point data set with temperature data I have, I want to create their Thiessen Polygons in R. So far, the only algorithm I have found is that of Carson Farmer (http://carsonfarmer.com/2009/09/...
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### Extracting centerline of a Complex-Polygon in PostGIS/Python

Any idea how to extract the centerline of the following polygon (Fig1) using PostGIS functions or Python modules? I was trying Voronoi Function but thats not helpful for this kind of shape. I want ...
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### Splitting overlap between polygons and assign to nearest polygon using PostGIS?

My question is quite related to the unanswered Split overlap between polygons into disjoint sets except I'm not using shapely, I'm using PostGIS 2.4 on PostgreSQL 10. I have a table containing ...
951 views

### Creating voronoi polygons from polygons?

I have a database with buildings and for some further analysis I need to: aggregate adjacent buildings (preferably without losing the height attribute, but I can work my way around that) once I have ...
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### How to find nearest neighbors of polylines?

I have a shapefile containing irregularly placed polylines (i.e., survey routes). Following the general idea of a paper I read, I would like to use tessellation to identify the neighbors for each ...
817 views

### Growing polygons with limiting area and boundary using ArcGIS Desktop?

I need to create polygons of a specific area based upon random points within bounding polygons, but haven't been able to find a tool able to do all these. I've looked at growing Theissen polygons, ...
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### Efficiently generate Voronoi layers in qgis via Python

The following python commands both appear to function when called in qgis 2.6 to generate Voronoi diagrams: processing.runalg("qgis:voronoipolygons", pointLayer, 1, None) processing.runalg("grass:v....
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### Insert n points equally distributed into many polygons

I know the "Random Points inside Polygons" tool in QGIS. It generates the below output. What I want to achieve however are 8 equally distributed points for each of the polygons. I thought of dividing ...
139 views

### Calculating the distance between the furthest vertex of a Voronoi polygon and the point from which it was generated

I need to calculate the distance between the furthest vertex of a Voronoi polygon and the point that generated it. I need to calculate this distance for all Voronoi polygons. Is there a way to do it ...
215 views

### Removing 'tails' from line features?

I have a set of polygon centerlines created using voronoi polygons. The method seems to work well for what I want to accomplish, but these 'tail' remnants are throwing off successive analysis (...
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### Growing several concave hulls until they completely fill larger area without overlap using QGIS? [closed]

This is my problem: I have a very large point layer with polling station locations across one country; each point belongs to a specific constituency (900k points, 4k constituencies). I wish to use ...
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### How to use ST_VoronoiPolygons() in PostGIS?

Sorry folks, I know it sounds like a lame question - and, yes I did read the manual... :-) I'm trying to make Voronoi diagrams around points I have in a PostgreSQL table. It should be rather easy - ...
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### Thiessen Polygon delineation within a Feature

I am trying to create Thiessen (Voronoi) polygons, based on points within a defined shapefile extent. The output should be inclusive to the feature. The output I receive now is the rectangular area ...
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### How to draw weighted voronoi polygons (thiessen) from points in QGIS?

I have a shapefile of polygons which have an amount of population, I need to divide each of these polygons into small ones with nearly equal population. So I thought attributing points on each area ...
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### What Is The Ideal Workflow To Map (British) Postcode Territories

I'm looking for the best workflow for mapping postcodes and calculated territories, but being relatively new to mapping I'm struggling on a few details and also the best practices for displaying these ...
287 views

### Create a line string from street geometry

I'm currently facing some hard times trying to create a simplified line from a street geometry. The data that I'm currently using comes from OpenStreetMap, using osm2pgsql.(Which means PostGIS, but I'...
509 views

### Flood fill formula for Voronoi cells on QGIS?

At the moment, I'm developing a map of a fictional West Indian nation with QGIS. Everything's gone as well as can be expected with this project--except for a shortcoming that stumped me on Thursday ...
264 views

### R - Voronoi polygons from lines

I use R (and sf, mainly) and I was wondering if it's possible to create Voronoi polygons starting from LINESTRING objects instead of POINT. For example, given a sfc such as # package library(sf) #&...
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### Voronoi Polygon Algorithm seems to exclude a Point from processing

I am using the QGIS (2.8.1) Voronoi Polygons Algorithm on a point shapefile. See image below, the red triangles are the points I am using. The resulting polygons miss a part (around HP87). Any ...
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### The drawing of Thiessen/Voronoi polygon boundaries - are the bisecting lines truly perpendicular?

I am concerned with how QGIS (version 2.8.1) and ArcGIS (version 10.0) draw "perpendicular bisecting lines" when Thiessen/Voronoi polygons are created. When using either program to create these ...
655 views

### Strange results with Voronoi polygons in QGIS

I'm trying to generate a Voronoi Diagram in QGIS 2.14.3 from 16 points. The result looks very strange, at least compared to what I expected. For me, at least the two yellow highlighted split are ...
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### Counting sides or edges of polygon using open source GIS?

I wondered if it is possible to determine the number of sides / edges (not vertices) that a polygon has. Imagine the following case. There is a shapefile with 10 polygons. Is there any way to ...
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### Calculating Voronoi Diagrams for polygons

There are a variety of good algorithms for generating the Voronoi polygons or their complement, the Delaunay Triangulation for a set of points. My question is simply, is there an algorithm for ...
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### What is math behind entropy calculation in ArcGIS Voronoi diagram?

ArcGIS for Desktop 10.3.1, Geospatial Analyst Toolbar, Voronoi Diagrams How is the entropy value calculated? What is the math? I have gone through ESRI's E-learning exercise. The exercise has a data ...
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### Issues in Intersecting Voronoi Polygons With Other Boundary Shapes (QGIS)

I'm having problems in intersecting Voronoi polygons with another shape. As the image shows, I want to clip the Voronoi layer at the red costal perimeter of the UK so that the additional surface area ...
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### Can Voronoi/Thiessen polygons be created using ArcObjects without 3D Analyst license?

Has any body used ITinNodeCollection to generate Voronoi/Thiessen polygons. I have a point featureclass for which I want to create Voronoi/Thiessen polygons. Does this require 3d analyst license?
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### Which tool or plugin for Theissen / Voronoi polygons in QGIS?

As I understand you can generate Voronoi polygons in QGIS (2.18.2) using the following approaches; Vector menu / Geometry tools / OR MMGIS plugin in I also read here that you could use SAGA as well. ...
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### How to define voronoi polygon buffer extend in QGIS from layer extend

I'm using QGIS (2.8.1) Voronoi Polygons Algorithm and I would like to extrapolate them to a polygon layer extend. In order to do this, the tool opens a window asking me to enter a number or expression ...
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### QGIS Voronoi polygons wrong behaviour

I am trying to use Voronoi polygons algorithm in QGIS in a dataset of points but strangely I am getting an overlap of polygons. These points correspond to the vertices of a set of polygons. When ...