The convex-hull tag has no wiki summary.
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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, ...
5
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2answers
115 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 ...
2
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1answer
59 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
68 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 ...
2
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2answers
96 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
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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 ...
8
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1answer
176 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 ...
6
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2answers
444 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, ...
3
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1answer
97 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
264 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
964 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 ...
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0answers
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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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3answers
2k 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) ...
4
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2answers
321 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 ...
6
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5answers
1k 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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6answers
1k 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 ...
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12answers
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Concave Hull: Definition, Algorithms and Practical Solutions
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 ...
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6answers
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How do I create a convex hull in ArcGIS?
I would like to be able to create a convex hull in ArcGIS 9.x, but I can't find an appropriate tool. How does one go about creating one? I am interested in answers for all license levels, ArcView, ...
