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.

Filter by
Sorted by
Tagged with
2
votes
0answers
346 views

Calculating area of voronoi polygons from real life data using QGIS?

I have an area, which I divided into voronoi polygons using data points. I have no problem creating the polygons. Now the data points are on a coordinate system, where every degree represents one ...
4
votes
0answers
223 views

Creating polygons from points using lines as barriers

This question is similar to a previous post where the member asked if it were possible to create Theissen (Voronoi) polygons from lines: Creating Thiessen (Voronoi) polygons using lines (rather than ...
3
votes
1answer
1k views

QGIS Voronoi Polygons Float Division by zero

I have created a vector which is a connection to Sql Server. I then select Vector > Geometry Tools > Voronoi Polygons. I select my input layer and a temporary file for my Voronoi polygons. I get the ...
14
votes
3answers
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?
1
vote
1answer
120 views

Masking the “infinity” part of Voronoi polygons in QGIS?

I have a shapely file with several polygons for a given country, together with information on its cities. I run the Voronoi algorithm on the cities' capitals and get the polygons for it. However, ...
1
vote
0answers
276 views

Voronoi / Thiessen polygons doesn't create a part for 1 of 4 input points

I am using QGIS to create Voronoi / Thiessen polygons for 4 rain gauges. I am having issues with both the QGIS 'Voronoi polygons' tool and the Grass equivalent 'v.voronoi' where one of my 4 points ...
2
votes
1answer
118 views

Choropleth of calculated Voronoi polygons?

I have calculated a voronoi layer for a set of points, I then joined said layer with counts so (almost) each point that generated that polygon has a number associated to it. My question is: how do I ...
4
votes
2answers
163 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 (...
1
vote
1answer
53 views

How can I identify which tracks are too close together?

I have a point shape (yield logging data) and I want to find the tracks that are too close to another track. Usually the combine drives always with the same distance (e.g. 10m). I want to find the ...
1
vote
1answer
768 views

PyQGIS Processing - wrong number of parameters

I'm facing a very strange issue from the module Processing using it as a standalone (not in the Qgis python console). I'm trying to create voronoi polygons from a points csv file. I can load my file ...
6
votes
2answers
641 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 ...
1
vote
0answers
76 views

Using angle attribute to split voronoi polygan to three small polygon in QGIS?

I have a point data set, that include [id] and [angle] attribute, like 0/120/240。I made voronoi layer use point, i want to use angle attribute split voronoi polygan to three small polygan, how to do ...
3
votes
2answers
1k views

Postcode mapping (QGIS): how to transform OS csv data to an polygon map (.shp)?

I am trying to obtain a full England postcode map (polygons) out of free (and reliable) data out there. The English National Office of Statistics does share a huge list of postcodes and some ...
1
vote
1answer
81 views

Scripting a population sum based on union

I'm having trouble automating a process to sum one field into a new field, summing whenever the value of an FID field from my Union is the same. I'm looking to sum the population, stored in field "...
4
votes
3answers
697 views

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 ...
4
votes
1answer
2k views

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 ...
2
votes
0answers
148 views

How to use ST_VoronojDiagram for points that are almost aligned?

I am trying to use the spatialite ST_VoronojDiagram function on a table containing four 4 points that are almost aligned: (1.01 2.02, 2.02 3.03, 10.01 10.02, 11.01 11.02). I wrote the following script ...
1
vote
1answer
1k views

R: Voronoi tesselation from long/lat data?

I want to create a SpatialPointDataFrame and Voronoi Tesselation from my .csv data downloaded from EPA, available here: http://uloz.to/xboQc7cu/no2-calif-csv I convert my data in SPDF format in 2 ...
3
votes
0answers
623 views

How to create a shapefile having Voronoi diagrams from the shapefile of an existing region?

I have a shapefile of a region and I want to generate random sub regions of that shapefile using Voronoi class of scipy.spatial package of Python. But I am a newbie to GIS. I found out about Voronoi ...
2
votes
1answer
606 views

Where can I find the version of scipy python package used in QGIS Lyon 2.12?

I am using QGIS Pisa 2.10. I want to use the Voronio class of scipy.spatial in QGIS python console. QGIS Pisa has 0.11 version of scipy package. This package doesn't have Voronoi class. I even tried ...
1
vote
0answers
362 views

Calculating area of intersection of polygon to another layer in ArcGIS for Desktop?

I am very new to GIS, especially ArcGIS. I am currently using ArcGIS 10.2, and I have 2 layer, namely the purple feature map(this layer is an import from arcgis online, it doesn't seems to be an ...
5
votes
0answers
402 views

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 ...
1
vote
1answer
85 views

Thiessen polygons modified for slope

I seem to recall to have read about Thiessen polygons which, instead of having straight boundaries, had some irregularly shaped sides. That was since those polygons were actually taking into account ...
12
votes
3answers
3k views

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 ...
2
votes
1answer
2k views

Split a polygons into many polygons based on points using ArcMap

I have: A polygon feature that is a national park boundary, A multi-point feature that are security guard posts (number = n ) of the same park. I want to divide the national park area into 'n' ...
12
votes
4answers
986 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 "...
2
votes
0answers
281 views

Creating polygons using mask layer?

I looked at this question, but it only answers part of my problem. I want to create Thiessen polygons based off of the green points within the blue polygon boundary ONLY. I've set the Processing ...
1
vote
1answer
182 views

voronoi / thiessen different CRS

I have the following problem in QGIS: I try to create voronoi polygons based on a shapefile (points; standard WGS84). The newly created voronoi polygons layer seems to be ok for the WGS84 CRS. But ...
0
votes
1answer
492 views

Interpolation from isolines vs Thiessen (Voronoi) polygons interpolation

I'm currently studying GIS and have come across a question in an assignment that I just can't answer. I've been googling my brains out for the last few hours and got nowhere... here goes... Identify ...
2
votes
0answers
2k views

How can I put Voronoi/Thiessen polygons on Google Maps for free with no programming knowledge?

The only thing anywhere close to what I describe in the title is this site: http://lpetrich.org/Science/GeometryDemo/GeometryDemo_GMap.html. It has a couple problems, though: 1. There is no easy to ...
0
votes
1answer
1k views

Add Points shp attributes to Polygon shp by Point location (as Spatial Join in ArcGIS)

I have a set of points in .shp (ESRI, available here: http://ulozto.cz/xGqRVFrR/voronoi-zip). I would like to calculate Voronoi tesselation from the points, thus create polygons. So far, so good. ...
0
votes
1answer
198 views

Cross validation in thiessen polygons interpolation

I apply Thiessen Polygons interpolation using the krige command in the gstat R package. Using krige without a variogram model sets automatically krige function to perform IDW, and when nmax parameter ...
1
vote
0answers
31 views

Does fixed classes exist in QGIS?

I'd like to create several images of voronois polygons in QGIS; each images having differents values joined to the voronois. I tried to load a qml style with the values I want to keep (8 classes : 0>...
0
votes
1answer
98 views

How to delimit point distances in ArcGIS for Desktop per Thiessen polygon

I have 2 shapefiles. The first set contains x,y coordinates for 1100 hospital locations. The second pair contains x,y coordinates of about 7000 villages that are served by the hospitals. This means ...
2
votes
0answers
237 views

Is there any way to set a processing extent for QGIS:Voronoipolygon?

I was playing around with the QGIS:voronoipolygons command line function from QGIS and noticed that there was no option for setting the processing extent. This causes QGIS to pick the minimum extent i....
4
votes
3answers
555 views

Thiessen polygons extend outside of extent of projection

I'm working on a geological project on the past position of continents (in ArcMap 10 Service Pack 5, build 4400). The tool I'm creating in Model Builder uses Create Thiessen Polygons and all input ...
11
votes
3answers
847 views

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 ...
0
votes
1answer
196 views

Fill larger polygon empty space with closest subset of polygons

Looking for an ArcGIS or QGIS solution. I need to divide up the space of the large single green polygon. Each new polygon would represent "nearness" to the purple polygons and have the ID of the ...
3
votes
0answers
971 views

Create Thiessen polygons using spatially weighted averages? [closed]

I have to create Thiessen polygons with the spatially weighted averages for specific contaminate concentrations from different borings. I have the Thiessen polygons created but this only shows me the ...
7
votes
2answers
5k 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/...
2
votes
0answers
3k views

Polygon of Voronoi cell using scipy.spatial?

I have points (e.g., lat, lon pairs of cell tower locations) and I need to get the polygon of the Voronoi cells they form. from scipy.spatial import Voronoi tower = [[ 24.686 , 46.7081], [ ...
1
vote
1answer
1k views

How to use Delaunay triangulation in QGIS?

I have to create a Thiessen polygon for a site in New Jersey and all I have right now is the concentrations from samples we took in the area. What else do I need and how do I input it into QGIS to get ...
7
votes
1answer
1k views

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....
3
votes
1answer
453 views

Thiessen Polygon Total Area Calculations Model Builder/Python Code

I am attempting to create a tool using Model Builder (and Python code) for calculating the average annual precipitation of a study area using the Thiessen Polygon Method. My model runs good other than ...
0
votes
1answer
158 views

Thiessen Ploygon Bifurcated Areas Calculations

I have a SewerGEMS network of a sewerage scheme for a town. The town is divided into 17 wards having different population densities in (Population/Hectare). There is an AutoCAD drawing showing the ...
1
vote
0answers
470 views

Calculations of Thiessen Polygon Bifurcated Areas

I have got a SewerGEMS network of a Sewerage Scheme for a Town. The Town is divided into 17 Wards having different Population Densities in (Population/Hectare). There is a AutoCAD drawing showing the ...
4
votes
3answers
1k views

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 ...
12
votes
1answer
5k views

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,...
8
votes
2answers
4k views

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 ...
11
votes
2answers
8k views

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.