Convex-Hull | convex hull by using Graham 's Scan Algorithm | 3D Printing library
kandi X-RAY | Convex-Hull Summary
kandi X-RAY | Convex-Hull Summary
convex hull by using Graham's Scan Algorithm
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- Perform the Graham Scan algorithm
- Merge two points
- Distance between two points
- Return theta of a point
- Return the distance between two points
- Draws a circle
- Create random points
Convex-Hull Key Features
Convex-Hull Examples and Code Snippets
def convex_hull_bf(points: list[Point]) -> list[Point]:
"""
Constructs the convex hull of a set of 2D points using a brute force algorithm.
The algorithm basically considers all combinations of points (i, j) and uses the
definition
def convex_hull_melkman(points: list[Point]) -> list[Point]:
"""
Constructs the convex hull of a set of 2D points using the melkman algorithm.
The algorithm works by iteratively inserting points of a simple polygonal chain
(meaning
def convex_hull_recursive(points: list[Point]) -> list[Point]:
"""
Constructs the convex hull of a set of 2D points using a divide-and-conquer strategy
The algorithm exploits the geometric properties of the problem by repeatedly
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Community Discussions
Trending Discussions on Convex-Hull
QUESTION
I'm trying to build species distribution polygons for use in the R program rase. The program requires an owin object but sample data also includes a SpatialPolygonDataFrame. You can get the data yourself with: data(rase_data, package = 'rase')
I'm starting with a list of coordinates (lat/long per species). Thanks to this answer here, I've been able to make a polygon per element of the list (each species). I need to get to an owin object. Here's the dput of some test data and then code I've used to get where I'm at.
...ANSWER
Answered 2021-May-09 at 19:54I do not know sf
enough to fix this, so I show it via terra
but the important part is the sequence of operations. You can implement that in sf
again if you wish. There should be no need to revert to the old Spatial*
objects
Your data
QUESTION
I have an image which I'm using skimage to try and detect:
how many images are actually within the page - I'm expecting it to 'count' 5
find the corners of each image - so if it counts 5 above our maxCorners should be 5*4=20
draw straight lines between each corner and 'mask' each of the 5 images
right now all I got is the image being read, doing a fill holes and thats about it - guidance on the rest?
...ANSWER
Answered 2021-Jan-15 at 23:45This Answer was the key to solve this problem.
Coords:
[[(38, 11), (251, 364)], [(254, 62), (592, 266)], [(254, 312),
(592, 518)], [(46, 456), (247, 797)], [(346, 557), (526, 797)]]
QUESTION
I need to find whether some of my points are inside or outside a convex hull and I was using this answer: (enter link description here).
But when I test it, the array that is returned is slightly confusing. For example if I create two identical arrays, use one to create a hull and then test whether points of the second are in that hull I get the following:
...ANSWER
Answered 2020-Oct-12 at 02:18tl;dr: It returns the index of a triangle containing the point. And it does not always pick the same index if there are multiple triangles containing it.
I think you misunderstood "It returns:Indices of simplices containing each point. Points outside the triangulation get the value -1."
My interpretation is that Delaunay(pts_outer)
triangulates your rectangle with two triangles with the indices 0 and 1 respectively. Then hull.find_simplex(pts_inner)
retruning [0, 0, 1, 1]
means that your first two points are in triangle 0 and the 2nd two are in triangle one.
Finally it is a bit odd that find_simplex
now tells you your point [5, 5]
is in triangle 1. But that is not incorrect since the point [5, 5]
is in both triangles.
QUESTION
TLDR: I need to construct a python object for fast interior point testing, similar to a SciPy ConvexHull
or DelaunayTriangulation
. The catch is that I know ahead of time the order in which the triangulation of the points must be constructed: (6 points, 8 triangular faces, with a specific ordering of each face). In effect, I already know what the convex hull should be, but I need it in a form that I can use with existing (and optimised!) libraries (eg Scipy spatial). How can I do this?
Context: I need to construct a triangular prism (imagine a Toblerone bar - 2 end faces, 6 side faces, all triangular) in order to do some interior point testing. As I will have many such prisms lying adjacent to each other (adjacent on their side faces, imagine many Toblerone bars stood on their ends and next to each other), I need to be careful to ensure that no region in space is contained by two adjacent prisms. The cross section of the prism will not generally be uniform, hence the possibility of overlap between adjacent prisms, as illustrated by this diagram of the approximately planar face between two adjacent prisms:
...ANSWER
Answered 2020-May-02 at 12:55Half a solution... Not an exact solution to the original question, but a different way of achieving the same outcome. Any triangular prism can be split into exactly three tetrahedra (see http://www.alecjacobson.com/weblog/?p=1888). This is a specific case of the fact that any polyhedron may be split into tetrahedra by connecting all faces to one vertex, if the faces does not already include it.
Knowing exactly how I would like the face triangles of my prism to be arranged, I can work out what three tetrahedra would reproduce the same configuration of triangles (with extra faces of course being added inside the original prism itself). I then form Delaunay triangulations around each of these three tetrahedra (ie, collections of 4 points) in turn and perform the original interior point tests: if it matches on any then I have a positive result for the whole prism. The key point is that by only giving four points to the Delaunay constructor at a time, I know exactly what triangulation it will return as there is only one way of forming such a tetrahedra (assuming no geometric degeneracy).
It's a bit longwinded, and involves 3x as many tests as I would like, but it's a start. If anyone in the future does know how I could do this better please do let me know.
QUESTION
ANSWER
Answered 2020-Feb-03 at 12:57Thanks to shapely polygons, on which trimesh is built you don't need to go over the vertices. You can use some of the inbuilt functions. After creating your 2D path you are almost there. The path has two attributes: polygons_full
and polygons_closed
. The first one is the outmost polygon without the inner ones and the second one are all polygons of your path.
You can simply do:
QUESTION
When I build PCL library on Jetson TX2 from source via CMAKE, I get the following debug logs among other msgs:
...ANSWER
Answered 2020-Feb-03 at 06:11I found a file which was causing the CMAKE to include 10 sm_arch in compatibility list. Here's the link. I will re-compile after editing the file for just 1 sm_arch and compare the size of binaries generated. – Anuj Patil Jan 22 at 18:10
So findCUDA was the culprit here. Editing the files to required sm_arch does the trick!
QUESTION
I am looking for distance from a point to a ConvexHull object in 3D in Python.
I found the questions that solve the problem in 2D: Distance to convexHull and Computing the distance to a convex hull
But those do not contain a solution for 3D.
...ANSWER
Answered 2019-Apr-02 at 22:26We can use PyGEL 3d python library for this.
First, install it with pip install PyGEL3D
Second, the code:
QUESTION
I'm trying to convert a webpage to PDF, using pdfkit but it shows following error
...ANSWER
Answered 2017-Feb-23 at 16:13Your config path contains an ASCII Backspace, the \b
in \bin
, which pdfkit appears to be stripping out and converting C:\Program Files\wkhtmltopdf\bin\wkhtmltopdf.exe
to C:\Program Files\wkhtmltopdf\wkhtmltopdf.exe
.
This can be resolved by using r
, which makes it a raw literal
QUESTION
ANSWER
Answered 2019-Jul-04 at 15:55It"s the classical problem of linear programming. Given a set of linear inequalities (represented by planes in your case, say ax+by+cz+d>=0) and a linear function (say f(x,y,z)=x), find a point that minimises the function while satisfying all the inequalities. The AABB is the solution of 6 such problems, for functions x, -x, y, -y, z and -z.
There are several methods of solving this problem, the most known being the simplex algorithm, and many ready-made libraries (including some that utilise GPUs).
QUESTION
I am trying to use CGAL's 3D Convex Hull generation function with a Point_with_info
. This is similar to this question CGAL: convex hull of points with info but for 3D instead of 2D. I am trying to follow the same strategy of using forwarding functors but I am getting many many errors which I expected the forwarding functors to handle. The following is the full code that I am trying to make work:
ANSWER
Answered 2019-Jun-12 at 14:35UPDATE: Based on the comments by @AndreasFabri, my solution is too convoluted. You can find a much shorter solution based on what is already implemented in CGAL https://gist.github.com/afabri/a32f0d1ac5af1a99491d62786a0d5559. I am copying the same code below:
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Install Convex-Hull
You can use Convex-Hull like any standard Python library. You will need to make sure that you have a development environment consisting of a Python distribution including header files, a compiler, pip, and git installed. Make sure that your pip, setuptools, and wheel are up to date. When using pip it is generally recommended to install packages in a virtual environment to avoid changes to the system.
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