Questions tagged [convex-hull]

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

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1answer
488 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 ...
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2answers
2k views

Openlayers 3: Draw Polygon (convex hull) around a cluster of points

I'm grouping a set of points as a cluster. Then I'm trying to draw a polygon around the points. Please see this link: Draw Poly I tried by sorting the points based on co-ordinates. But still I'm not ...
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1answer
505 views

QGIS generate convex hull for common attributes that have many values

If I have a points file where the points share common attributes, what's the best way to draw a convex hull around those common points using QGIS?
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0answers
30 views

Create polygons convex hull with arc basic [duplicate]

I have a bunch of polygons to make from points that need to be more precise than the min bounding box of closest rectangle or circle but don't have an advanced license. Does anybody have a workaround ...
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2answers
178 views

Creating a large amount of convex polygons using existing coordinates

I downloaded the georeferenced event dataset (top left) from this website: http://ucdp.uu.se/downloads/ It consists of coordinates of violent conflicts which differ in time and space. My aim is to ...
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2answers
231 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 # ...
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0answers
127 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 ...
4
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1answer
512 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) ...
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2answers
35k 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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1answer
423 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 ...
5
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1answer
3k 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?
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0answers
424 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, ...
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1answer
117 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 ...
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0answers
360 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 ...
2
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1answer
3k 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? ...
2
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1answer
162 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
3
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1answer
307 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: =&...
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1answer
1k 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 ...
4
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1answer
388 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 ...
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2answers
1k 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 ...
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2answers
931 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 ...
2
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2answers
692 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 ...
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0answers
671 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 ...
3
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1answer
298 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 ...
5
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1answer
1k 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 ...
4
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1answer
5k 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 ...
5
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2answers
836 views

Invalid Geometry Error after ST_ConvexHull

I've a Postgis table of around 80,000 points and want to be able to populate a second table summarizing the data with convex hulls based on points with a common attribute. For example, the data ...
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5answers
4k views

Algorithm to find polygons enclosing points

I'm trying to find an algorithm that can determine the smallest possible polygons to cover a number of points. I know how to get the convex hull around all the points, but say that the points are ...

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