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19 views

Allocation of data by Voronois to admin units according to area in QGIS? [duplicate]

In QGIS, I need to assign values from Voronoi cells into admin 2 units (e.g., counties) with a weighted average according to the amount of territory of each county covered by the cell. So, for ...
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0answers
17 views

Why when I create Thiessen Polygon it didnt start at middle line beetween two points?

I must asking this, in ArcMap 10.2 why the thiesen poligons didnt divide at median line? it was move at +- 3 meters from the median line. Why is this happening?
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1answer
39 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
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1answer
45 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 ...
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0answers
13 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 : ...
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1answer
67 views

How to delimit point distances in ArcGIS for Desktop per thiessen polgyon

I have 2 shapefiles. The first set contains xy pair for 1100 hospital locations. The second pair contains xy of villages about 7000 that are served by the hospitals. This means each hospital serves ...
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0answers
58 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 ...
2
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0answers
28 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 ...
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0answers
44 views

Considering “holes” 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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0answers
63 views

How can I create weighted voronoi (thiessen) polygons within a constraining polygon?

I have been experimenting and trying to find a way to create weighted theissan polygons, within a constraining polygon with no luck. I am also not too familiar with python which I am sure is a ...
0
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1answer
38 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 ...
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0answers
100 views

Create Thiessen polygons using spatially weighted averages?

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 ...
2
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1answer
235 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 ...
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0answers
301 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], [ ...
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1answer
179 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 ...
2
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0answers
137 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) ...
3
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1answer
109 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
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1answer
51 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 ...
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0answers
103 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 ...
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3answers
278 views

How to count the sides or edges of a polygon?

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 ...
8
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1answer
1k views

How to use ST_DelaunayTriangles to construct a Voronoi diagram?

With PostGIS 2.1+ we can use ST_DelaunayTriangles() to generate a Delaunay triangulation, that is a dual graph of its Voronoi diagram, and, in theory, they have an exact and reversible conversion. ...
3
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1answer
705 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 ...
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2answers
2k 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.
2
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1answer
75 views

What is the correct cartographic projection to calculate a Voronoi tesselation?

I have a set of points with known geographic coordinates. I would like to compute a Voronoi tesselation from these points in order to obtain areas of influence. The geometrical area of each Voronoi ...
3
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3answers
507 views

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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1answer
118 views

Thiessen polygons of sub-districts to lie within district boundaries [duplicate]

I'm using ArcGIS 10.1 and am fairly new to it. I have the latitude and longitude of sub-districts, and wish to create Thiessen polygons of these sub-districts. I also have shapefiles for districts ...
2
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0answers
63 views

Iterative point feature removal based on Thiessen polygon values

The background is: I have point feature class and Thiessen polygons created based on it. I wanted to know for each point Thiessen polygon area value, so I have calculated Thiessen polygon area value ...
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2answers
395 views

Creating Thiessen polygons gives ArcGIS ERROR 000537 error in converting points to Voronoi Polygons?

I have a problem with creating Thiessen polygons for a set of points. I am creating them with Create Thiessen Polygons tool in ArcGIS 10.1). I am able to create them in a few steps (for parts of the ...
1
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1answer
171 views

Smoothly interpolating Polygons from set of coordinates?

I'm still quite new to QGIS and I'm using it to display and analyze my soil data. I have point information on the distribution of the soils in a specific area and I need to create a soil map from ...
1
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1answer
203 views

Get Coordinates of Voronoi Polygon Vertices [duplicate]

Is there any chance to get the exact coordinatas of the voronoi polygons? I am using Qgis software and I have the "center" (redpoint) of the polygons and I would like to export the polygons corners ...
9
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1answer
347 views

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 ...
5
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1answer
295 views

How to grow several concave hulls until they completely fill a larger area without overlap?

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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0answers
106 views

Grass 7 voronoi vertices error

I tried the voronoi diagram for area function and got the message "ERROR: Found 0 vertices" - any suggestion ?
0
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1answer
104 views

Graduated colouring Voronoi polygons? (QGis)

I've got a huge database of depth points for the whole Irish sea which I'd like to be a nice smooth surface, or at least have a depth value associated with the entire area (i.e. include the ...
3
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4answers
393 views

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? I ...
5
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1answer
1k views

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 ...
0
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1answer
382 views

Offsetting Points by location

Sorry If you've read this before - I've tried to change the content so that it reflects what I need a little better. This question was marked as a duplicate although I read the the answer to the other ...
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0answers
923 views

Create Voronoi/Thiessen polygons in QGIS around 3 points

Running QGIS 1.8.0 I have three bus compounds. I would like to generate Voronoi/Thiessen polygons around those three points. Following Voronoi/Thiessen adding an all school points will allow us to ...
6
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1answer
480 views

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 ...
3
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0answers
221 views

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. ...
3
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3answers
645 views

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 ...
3
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1answer
628 views

Python Script that calls the Voronoi Polygons Function?

I've been looking to see if there was a way to call Voronoi Polygons function found in Vector/Geometry Tools, directly from the code but I have not found one. Does this currently exist? Is there a way ...
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5answers
6k views

How best to fix a non-noded intersection problem in 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 ...
9
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2answers
6k 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, ...
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3answers
994 views

Thiessen polygon input help

I am new to 10.0 and have never used the thiessen polygon tool -- i have a set of points and would like to create a thiessen polygon; what do i need to input (i.e. what type of input (.shp etc)?
8
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1answer
553 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. ...
16
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1answer
2k views

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 ...
4
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1answer
6k views

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 ...
2
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0answers
321 views

Proximity Toolset Questions - Description, Examples of Usage, and Limitations

I was wondering if you could help me answer a few questions about the Proximity Toolset. I have been given the task of describing each tool in laymen terms, the typical usage of each tool, and most ...
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2answers
4k 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