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Questions tagged [convex-hull]

Convex-hull of a set of points X in a Euclidean space is the convex set with smallest area that contains all points of X.

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convexHull - "Invalid arguments" - OpenCV 2.4.9

I have this C ++ OpenCV code ... vector hierarchy; vector > contours; findContours(bin.clone(), contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0)); // Find the convex hull object of the external…
João Luiz
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How to find the 'outline' of a (concave) graph in 2D plane?

I have a connected graph in 2D plane composed of some vertices and some edges defined between them. The overall shape of the graph is not necessarily convex, i.e. the adjacent vertices on the convex hull are not always connected by an edge. Now is…
Niko
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convex hull of three orthogonal line segments

I got three line segments in 3D. They are pairwise orthogonal but they don't need to touch. If they touch, the volume of the convex hull of them is 1/6*s1*s2*s3 where s1,s2,s3 are the lengths of the line segments. This can be easily computed. But…
Nad
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Ensuring that all points are on the convex hull of a triangulation

I currently have a program that takes in a set of points, triangulates it using CGAL, and then extracts the convex hull of these points. However, I was wondering, instead of finding the convex hull of the points, how can I create a triangulation…
user1549792
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How to check a point is inside a ConvexHull using CGAL

I have created a convex hull with some 3D points using the CGAL library. Now I want to check whether a point is inside the hull or not. But couldn't find any options to do so. Can anyone help? My code is bellow. #include…
sabby
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OpenCV convexhull doesn't give correct output

This is my input binary image: Now I want to get its convex hull using OpenCV. For that, I wrote the following code: cv::Mat input = cv::imread("input.jpg", CV_LOAD_IMAGE_GRAYSCALE); cv::vector>…
E_learner
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Gift Wrapping Algorithm (Jarvis March) - Single Run using Cross Product

In the well known "Introduction to Algorithms - 3rd edition" book the Gift Wrapping Algorithm for finding the Convex Hull of a set of points in 2D space is described as requiring either: 2 runs for finding the left and right chain of the convex…
user4906922
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Convex Hull - Reading from input file

I am trying to read the x,y coordinates from a file that has 1000 entries. This is what I have so far: int n=4; Point2D []p = new Point2D[n]; p[0] = new Point2D(4,5); p[1] = new Point2D(5,3); p[2] = new Point2D(1,4); p[3] …
user01230
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Convex hull of all co-linear points?

This is pretty trivial, but still I wanted to know what would be the convex hull if the points are characterized by line x = y i.e. all points are co-linear.Would that be the same case as 2 points i.e. the line segment joining all the points
Aditya Bahuguna
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What is the upper bound on the number of antipodal pairs?

Antipodal pair is pair of vertices x,y such that we can draw parallel tangents to convex-hull H through vertex x and y without intersecting H. I found many algorithms to find such pairs, but i am not able to derive the upper bound on number of…
CodeLover
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N-dimensional convex hull qhull algorithm optimality

Why quick hull algorithm works with farthest point in outside set of facet instead of working with point, which gives maximum volume for simplex, resultant from the facet and the point? If points are uniformly distributed in space (general case),…
Tomilov Anatoliy
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Reducing/simplyfing polyhedrons

I am looking for an algorithm that can reduce/simplify polyhedrons - reduce the number of its vertices while preserving the shape of the object. I have a set of points in 3D that represent a convex hull of an object and I would like to create a…
jolly
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Qhull(Qhalf) interior point

I am using qhull library for for computing the intersection of half spaces. Although this problem is a dual of convex hull problem, but as its input it needs an interior point of the intersection. As it is stated on their webpage, here, using linear…
Hamed
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Convex hull / concave hull for multiple clusters in data

I have done a lot of reading on drawing polygons around clusters and realized convhull maybe the best way forward. Basically I am looking for a elastic like polygon to wrap around my cluster points. My data is matrix consisting of x (1st column) and…
user3299469
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Given a set of lines/corners (shown), determine largest quadrilateral?

Given something as follows (points are known for corners, equations are known for lines), how can I determine the largest/outermost quadrilateral/set of lines/set of corners? I'm stumped. The closest thing I've come across is a convex hull, but this…
user2133809
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