# Tagged Questions

Smallest bounding area for an object or group of objects with no concave angles.

32 views

### Summarizing point data to multi point data and creating convex hull in R

I have latitude and longitude information like 26.847905 73.9575005 for about 800 points, I need to trim these lat/lon information to say 3 decimal places. I used the following syntax in R # ...
364 views

### Creating polygons layer from point layer with conveks buffer

I have a point layer of >750000 points representing dwellings with district heating. Now, I want to create polygons for every n of points with a distance of n meters to the next point. I have a ...
64 views

### Adapting a ConvexHull fonction to a ConcaveHull one

I have a database with over 150 000 points in a EPSG 2950 projection. As I wanted to cluster those points in polygons, I used a ConvexHull fonction. The goal was to create clusters where I would find ...
75 views

### Clustering (ConvexHull) data based on distance

First I would like to mention that I am not an expert with PostGreSQL so my question may seem dumb, but here it goes: I have a database with over 800 000 points associated to a geometry (EPSG 2950) ...
12k 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, ...
57 views

### Packing polygons without intersection and empty places [closed]

How can I pack polygons without empty places and intersections? Please tell me everything that might help me (API, algorithms, etc.) I'm using: USPS API to get carrier routes. dbscan.js to ...
29k views

### What are Definition, Algorithms and Practical Solutions for Concave Hull?

Convex Hull A convex hull of a shape is defined as: In mathematics, the convex hull or convex envelope for a set of points X in a real vector space V is the minimal convex set containing X (...
26k views

### How to find the minimum-area-rectangle for given points?

The following is another problem that I am working on it these days. As you see in the figure, (BTW, I tried to make it self-presenter) the question is: How to find the minimum-area-rectangle (MAR) ...
140 views

### Is there a QGIS equivalent to ArcGIS' Convex Hull and Circle under the Minimum Bounding Geometry tool?

I have the opportunity to run ArcGIS and QGIS side by side for a few months and was looking to see what comparisons there are. So I'm interested to know if there is a similar tool on QGIS?
13k views

### How do I create a convex hull in ArcGIS Desktop?

I would like to be able to create a convex hull in ArcGIS Desktop 9.x, but I cannot find an appropriate tool. How does one go about creating one? I am interested in answers for all license levels: ...
33 views

### OpenJump LoCoH Analysis Output?

I really need some help! I am doing a k-LoCoH analysis in OpenJump. The analysis is working, but I'm having trouble understanding the output. There is a "density" column in the output, and I'm not ...
313 views

### Convex Hull issue in QGIS 1.8

When creating convex hulls based on input field in qgis 1.8, there seems to be always one less convex hull created for the unique values in the input field. For example; I have a point vector file, ...
88 views

### get the outline of a polygon

I have geojson data that draws shapes similar to the following: I wanted to know if there are any operations that can give me the geojson which represents the outline of these shapes represented by ...
107 views

### Extracting points bordering shape extent

I'm using ArcGIS 9.31. I have a set of points as elevation and in order to get a soft clip area for the TIN, I would like to extract only all the points bordering the extent of this shape, or to get ...
146 views

### Inflating the boundaries created with convex hull

I have a set of lan and lat points and have plotterd a convex hull for them using QGIS. A polygon is created along the set of points and plotting them on the MAP. Now I am trying to inflate the size ...
319 views

### Convex Hull operation not specific enough

I have yield data as point values, and I simply want to create the boundary around this layer. I have used the Minimum Bounding Geometry tool and selected Convex Hull to do this, however it maintains ...
41 views

### How to find the the boundary co-ordinates from a given set of coordiantes? [duplicate]

How to find the the boundary co-ordinates from a given set of co-ordiantes? I understand that this question asked previously and answered here How to find the boundary co-ordinates from a given set ...
7k views

### How to find the boundary co-ordinates from a given set of co-ordinates

Given a set of coordinates, How do we find the boundary coordinates. <== Figure 1 Given the coordinates in the above set, How can I get the coordinates on the red boundary. Boundary is the polygon ...
485 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 ...
875 views

### Creating perimeter around multiple polygons using ArcGIS for Desktop?

This may have a simple answer that I'm just missing. I have multiple polygons in one shapefile I would like to make a larger Polygon around all of them. Is there a tool that is able to do this? ...
89 views

### Make convex hulls opaque or transparent

I have a series of convex hulls that I want to overlay but I want to be able to see all of them at the same time. How do I do this so? I'm guessing making them slightly transparent will do the trick
105 views

### PostGIS ST_ConvexHull for cube corners not as expected

I'm new to PostGIS and am wondering whether ST_ConvexHull will be of use in a particular work problem. Trying out some simple cases to make sure I understand what it's doing, I didn't expect this: =&...
435 views

### Postgis create polygon extent/convex hull from spatial table

Please help, I have a polygon layer representing building footprints. I want to create new view in postgis that will contain rectangle representing bounding box and also another view that will have ...
421 views

### Is there a Cluster convex hull implementation in OpenLayers?

In this leaflet example. When hovered over a cluster marker, it shows the bounding area of the clustered features which is known as convex hull. Is there a way to reproduce it with OpenLayers?
135 views

### R - Occasional error when using alphahull package areaahull() function

I've recently started using the fantastic alphahull R package, which works beautifully most of the time but occasionally I am getting the following error when running the areaahull() function: Error ...
225 views

### How to detect turns of a route?

I'm doing a Python simulation of a vehicle, driving along a specified path. I generate dummy GPS readings, that fetch the current position of the vehicle, with some randomized error added. After a ...
190 views

### Is there a way to visualize a convexhull in qgis 1.8 lisboa?

There is no way to visualize a convexhull in qgis 1.8 lisboa? I have tried following views in Postgis 1.5 I was told to use an id column to publish it in Qgis. If you not use an id column, u cannot ...
160 views

### Best way to 'join' polygons

I'm looking for the best ways to 'group' a budge of block polygons in a new polygon that should be the town. My block layer is something like this: Or zoomed: And I'm looking to get something ...
849 views

### How to build a minimum convex hull crossing the 180 degrees line?

I've been building convex hulls for species that inhabit the Indo-Pacific (~ from 20 to -65 degrees of longitude). The problem I've encountered is that for the species that can be found on both sides ...
585 views

### Quick way to make a convex hull

I am using Python and ArcGIS 10.1. Is there a function or very quick way to extract points out of point feature class into an array without looping through a search cursor (as I have millions of ...
790 views

### inner convex-hulls in a set of 2D points

A set of 2D Points are scattered randomly (i.e., no specified pattern), we are interested in finding all inner-convex-hulls (ICH) in an order of largest in area to a minimum until the entire study ...
505 views

### Is it possible to get the points used for the convex hull in osm2po?

I have a non-convex hull algorithm that I want to use for an app. With OSM2PO, it's possible to get a convexHull, but is there a way to get the points before the hull is constructed? More, it would ...
404 views

### How can I use Convex Hull to select an area with a space from the points?

This refer to this post : Read Here My goal is to select an area covering some points, but maintaining some space from points of border, like in the follow picture : I think ST_Convexhull will do ...
217 views

### Convex Hull in SAGA Gis

How does one go about creating a convex hull from a set of points in SAGA GIS? I read that this is possible in QGIS, but I prefer SAGA and would like to see if it is possible. Furthermore, if it is ...
778 views

### create convex hull polygons / cluster for sets of N points in a point dataset

I have 50k points in a feature class which I need to build convex hull or polygon for each set of 50 points that are nearby each other. I guess the question is very similar to create census areas for ...
3k views

### Best way to get Convex Hull/Boundary of millions of points

I've been trying to do some point analysis on some xyz data, I'm at the point where I've decided it is best to produce a boundary of my xyz files and put this with the metadata for each survey. Now ...
354 views

### convex hull over selected features

I am trying to achieve a convex hull over a feature Set returned by a query. But have been facing the error below which i am not able to figure out In order to debug to see how the convex hull works ...