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Results for "concave hull" "convex hull"
Search options not deleted
144
votes
14
answers
79k
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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 (Wikipedia) … Concave Hull
A concave hull is visualized using the red line in the image below (the blue line visualizes the convex hull). …
10
votes
1
answer
7k
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C# implementation of concave hull / alpha shapes [closed]
I'm looking for a C# implementation of the Concave hull (alpha shapes) algorithm.
I already found several Java, Python and C++ implementation but no C# version. … This will produce a convex hull, which I don't need.
Something like this is what I need: http://www.geosensor.net/phpws/index.php? …
4
votes
3
answers
16k
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How to find the concave hull for a cloud of points in 3D space?
The existing algorithm for convex hull is not able to capture the feature for a set of 3D points. … Moreover, I found few mathematic tools have this function to obtain the concave hull and their responding points.
Given the data of spheres:
x1 y1 z1 radii_1
x2 y2 z2 radii_2
... …
7
votes
0
answers
187
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How to change the Point Cluster circle symbol to a convex hull
I would like to build an expression applied to a circle symbol that substitutes the circle symbol for the convex hull or concave hull geometry that operates with the Point Cluster render algorithm used … Here is a simulation screenshot of what I am looking for:
The goal would be to use the Geometry Generator to change the circle symbol for a convex hull geometry that visualizes the grouped points inside …
1
vote
0
answers
366
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Simplify Polygon - no loss allowed, looking for a concave hull - ArcMap
hull polygon, but that follows the edges into the convex areas. … So, before I jump into the rabithole fully, is there a way to produce a concave hull efficiently within ArcMap / ArcPy? …
1
vote
Making Outside Buffer in QGIS?
The screenshot shows the concave hull in red over the convex hull in purple.
There are still a few yellow lines within the concave hull, but it is much better than the convex hull. …
4
votes
1
answer
7k
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Best way to get Convex Hull/Boundary of millions of points
Now the part im stuck on is I've got over 15,000 surveys to compute the boundary of, tried convex hull and concave hull with varying results. …
10
votes
QGIS equivalent to ArcGIS Aggregate Polygons?
While the creation of a convex-hull is a pretty straightforward operation, because there is only one possible convex-hull for a given set, this is not true in the case of the concave-hull. … Santos (2007): Concave Hull: A k-nearest neighbors approach for the computation of the region occupied by a set of points
Other open-source GIS implementations of convex-hull computations are available …
10
votes
Accepted
Smoothing round border of created buffer in QGIS
This is a case for a convex or concave hull - depending how much additional space you want to include. … Concave hull gives you more flexibility: there is just one single convex hull per geometry, but different possible concave hulls (depending on input paramenters). …
6
votes
Filling gaps between polygons using QGIS
Wouldn't you want a concave hull? A convex hull will give you a large amount of area that isn't part of the block. For example, a convex hull would fill in that big gap in the "hook" park of block 1. …
9
votes
What are Definition, Algorithms and Practical Solutions for Concave Hull?
QGIS does have Concave hull algorithm. … Parameters
Input point layer [vector: point]
put parameter description here
Threshold (0-1, where 1 is equivalent with Convex Hull) [number]
put parameter description here
Default: 0.3
Allow holes …
6
votes
How to find the concave hull for a cloud of points in 3D space?
A convex hull is unique, whereas there are many possible concave hulls. So you cannot say "the concave hull" but "a concave hull". … There is possibly a minimal volume concave hull, but this is not the case on the example you shown. …
1
vote
Simplifying polygon edge while preserving minimum area and width
There are at least two possibilities: convex and concave hull. This is not software specific, both kind of hulls can be created with different software packages. … Concave hull: Menu Processing / Toolbox / Concave hull (k-nearest neighbor). …
3
votes
Accepted
Creating polygon around set of points using PyQGIS
Using the "Concave hull (alpha shapes)" geoalgorithm. … hull) to 1 (convex hull)) should be done. …
9
votes
Accepted
Algorithm to find polygons enclosing points
K-means clustering) first, followed by a hull (convex hull, but a concave hull may have a smaller area but more difficult to implement). …