voronoi

R_Calculating Thiessen weights for an area with irregular boundary

杀马特。学长 韩版系。学妹 提交于 2019-12-04 23:27:09
I want to calculate Thiessen weights to compute areal rainfall from number of point measurements. I am using R and thanks to some previous question in the same topic, I got to know that I can use deldir . But the problem is my boundary polygon is not a rectangle; it's an irregular polygon (it's a catchment boundary derived using ArcGIS). But in deldir the boundary can only be a rectangle. Are there any other packages where I can calculate Thiessen weights of an area covered by an irregular boundary? Given below are my measurement points (meas_points) and coordinates of a (simplified) boundary

centerline of a polygonal blob (binary image)

别等时光非礼了梦想. 提交于 2019-12-04 21:00:32
问题 I have a binary image of a worm (blob extraction which works well). I am interested in fitting a centerline on the blowb (worm). So far I came up with this: starting from a polygon (after outline extraction of blob in the image) I applied a voronoi computation and discarded all vertices which are outside of the polygon (blue) which gave me the black center line which I can further use to fit a smooth centerline. However, this computation is not at all robust (due removing voronoi vertices not

Compute the size of Voronoi regions from Delaunay triangulation?

一世执手 提交于 2019-12-04 14:42:31
I would like to compute the mean and standard deviation of the areas of a set of Voronoi regions in 2D (if the region extends to infinity, I'll just clip it to the unit square). However if possible I would like to do this computation from the Delaunay Triangulation without explicitly computing the Voronoi regions? Is this even possible, or is it better to just compute the Voronoi diagram explicitly? In order to calculate the voronoi region of a vertex you need to iterate the 1-ring around it. Then the area of the region is defined as: A = 1/8 * (sum for every adjacent vertex p_i) { (cot alpha

How to color voronoi according to a color scale ? And the area of each cell

99封情书 提交于 2019-12-04 10:49:19
Is it possible to color the scipy.spatial.Voronoi diagram? I know it is. But now my goal is to color each cell according to a color scale to represent a physical quantity. As in the image below (PRL 107, 155704 (2011)): And I would also like to know if it is possible to calculate the area of each cell, because it is a quantity that I would like to calculate The Hagen Color scale: Actually the link you provide gives the code needed to colorize the Voronoi diagram. In order to assign each cell a color representing a physical quantity, you need to map the values of this physical quantity to a

Finding near neighbors

谁说胖子不能爱 提交于 2019-12-04 10:12:36
问题 I need to find "near" neighbors among a set of points. There are 10 points in the above image. Red lines are edges from the Delaunay Triangulation, black stars mark the mid-lines of the edges, blue lines are the Voronoi tesselation. Point 1 has three "near" neighbors, i.e. 4, 6, and 7, but not 2 and 3, who are almost in line with the edge 1-7, but much further away. What is a good way to identify the near neighbors (or "good" edges)? Looking at the figure, it seems to me that either selecting

Project Scipy Voronoi diagram from 3d to 2d

非 Y 不嫁゛ 提交于 2019-12-04 09:56:33
I am trying to find a way to calculate a 2d Power Diagram in Python. For this I want to make use of the fact that a 2d power diagram can be interpreted as the intersection of a regular 3d voronoi diagram with a plane . With the SciPy Voronoi module I can calculate a 3d Voronoi diagram - is there a possibility to intersect it with a plane and convert it to a 2d diagram? There isn't yet a power diagram capability inside of SciPy. Converting a 3D Voronoi diagram into a 2D power diagram is likely to be difficult and, at least within Python, slow. To work around this, I've developed a C++ program

Finding out if a point is inside a voronoi cell

白昼怎懂夜的黑 提交于 2019-12-04 07:53:11
Is there a simple way to find out if a point is inside a voronoi cell? For example, the following code generates something like the diagram below: using namespace boost::polygon; point_data<int> p1(0, 0); point_data<int> p2(-10, 10); point_data<int> p3(-10, -10); point_data<int> p4(10, -10); point_data<int> p5(10, 10); std::vector<point_data<int>> pts = { p1, p2, p3, p4, p5 }; construct_voronoi(pts.begin(), pts.end(), vd); In this case, how can I found out if the point (5,5) is inside the central cell? I could create a polygon out of each cell and find out using a point in polygon algorithm ,

Finding voronoi regions that contain a list of arbitrary coordinates

百般思念 提交于 2019-12-04 07:06:29
I am working with an algorithm that, for each iteration, needs to find which region of a Voronoi diagram a set of arbirary coordinats belong to. that is, which region each coordinate is located within. (We can assume that all coordinates will belong to a region, if that makes any difference.) I don't have any code that works in Python yet, but the the pseudo code looks something like this: ## we are in two dimensions and we have 0<x<1, 0<y<1. for i in xrange(1000): XY = get_random_points_in_domain() XY_candidates = get_random_points_in_domain() vor = Voronoi(XY) # for instance scipy.spatial

How to Bound the Outer Area of Voronoi Polygons and Intersect with Map Data

你离开我真会死。 提交于 2019-12-03 23:47:30
Background I'm trying to visualize the results of a kmeans clustering procedure on the following data using voronoi polygons on a US map. Here is the code I've been running so far: input <- read.csv("LatLong.csv", header = T, sep = ",") # K Means Clustering set.seed(123) km <- kmeans(input, 17) cent <- data.frame(km$centers) # Visualization states <- map_data("state") StateMap <- ggplot() + geom_polygon(data = states, aes(x = long, y = lat, group = group), col = "white") # Voronoi V <- deldir(cent$long, cent$lat) ll <-apply(V$dirsgs, 1, FUN = function(x){ readWKT(sprintf("LINESTRING(%s %s, %s

Python finite boundary Voronoi cells

岁酱吖の 提交于 2019-12-03 20:16:19
问题 I am trying to adapt a code I found on stackoverflow to create a voronoi cell with finite boundaries. I found the code below on https://stackoverflow.com/a/20678647/2443944 however my problem is that whilst the voronoi cells do not go off to infinity at the boundaries, they are still too far away. Even with a radius = 0, the ridge vertices are far too away. I ideally want the boundary voronoi vertices to be spaced around the same amount as the rest of the voronoi cells in the centre i.e. I