Questions on the use and creation of meshes including the use of MeshRegion, ElementMesh, and TetGenLink.

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19
votes
3answers
2k views

Removing unwanted appearance of underlying mesh

Let us first define two positive definite matrices: M1 = {{2, -6}, {4, 8}}; M2 = {{2, 3}, {4, 8}}; then set two points ...
8
votes
2answers
323 views

DelaunayMesh in a specified closed region - creating a concave hull from a set of points

I have a list of discrete points wich I want to use as nodes for creating a 2D mesh. I used DelaunayMesh and it works fine. The problem that I have is that some elements/polygons are outside of the ...
30
votes
4answers
4k views

Creating a 2D meshing algorithm in Mathematica

As what is proving to be a difficult, but entertaining task, I am attempting to adapt a 2D meshing algorithm created for MATLAB and port it to Mathematica. I understand meshing functions already exist ...
14
votes
3answers
2k views

Finding a Concave Hull

I have a 3d clustered data: Is there any other way to get concavehull of 3D data points?
12
votes
3answers
1k views

Dashed mesh behind 3D object

I am trying to create a simple, almost transparent 3D sphere with a mesh that is made of solid lines if they are on the front surface (i.e. if they are directly visible) and of dashed lines if those ...
20
votes
3answers
1k views

Build a refined grid based on intersecting line

I honestly have no idea where to begin with this problem. In summary, I have a 2D coarse grid with an intersecting line. For an easy example, let's assume it's a 4x4 grid. I wish to pass through ...
15
votes
3answers
3k views

Create triangular mesh from random list of points

I have a list of points. I would like to take these points and create a mesh of triangles from them, making sure triangles don't overlap. So here's a list of points: ...
14
votes
3answers
354 views

How to convert a surface into a solid

Context I am interested in converting surfaces into solids (so I can make a 3D mesh out of them using ToElementMesh) Say I have the following cool surface ...
8
votes
0answers
304 views

How to create an ElementMesh of a Sphere

I want to create an ElementMesh of a "sphere". To reduce the computational effort I want to use HexahedronElement; the ...
21
votes
2answers
673 views

Convert binary voxel image to geometric region

I have a binary voxel image which described a contiguous region in space. Example: ...
16
votes
4answers
2k views

How to get actual triangles from DelaunayTriangulation[]?

The ComputationalGeometry package has a DelaunayTriangulation[] function. It returns a list of points connected to each point, ...
7
votes
2answers
296 views

Mesh at Ticks positions

In a ListPlot3D[ ] I want to have the Mesh at the same positions as the ticks. For some reason this isn't default if both are ...
7
votes
1answer
1k views

Construct a simple mesh or tetrahedral mesh from 3D image surface

I have a 3D Y-Shape hollow tube, not so good surface. Import["http://dl.dropbox.com/u/68983831/tube02.vtk", "Graphics3D"] I tried to use following vertex data ...
6
votes
1answer
441 views

Meshing the surface of a non-convex object

I would like to mesh the surface of a cloud of points that may not be completely convex, for example the points in this question. Mathematica does not provide triangulation of 3D points, but there is ...
4
votes
4answers
265 views

Colouring points in a Delaunay Mesh by the number of nearest neighbours

I apologise if this is a repeated question, but I've searched for a while and can't find anything. I'm doing some molecular dynamics simulations using Mathematica 10, and I've placed a ...
4
votes
2answers
521 views

Different MeshStyle for different functions

By using Plot command I want to get one curve in form if circles and other like a solid line. ...
3
votes
4answers
142 views

Invalid region for small angles. To Element Mesh. Finite element method

I would like to mesh the region below in order to use it for a calculation by means of NDSolve. Could anyone help me to discretize this region for NDSolve using. Thank you very much. ...
1
vote
2answers
296 views

How to find adjacent polygons of a specific polygon in a VoronoiMesh?

I have developed a code for VoronoiMesh. I am also able to find the polygon with highest number of adjacent polygons. How do I find the indices of the adjacent ...
1
vote
1answer
340 views

Create hexagonal mesh on 3D Parametric Plot and 3D spheres?

I am looking to put a cool geometric mesh on this object. I came across this question that explained how to put a hexagonal mesh on a parametric equation but I have a series of geometric objects of ...
12
votes
2answers
795 views

How to create subregions for the NDSolve FEM Solver

I am trying to create a 2d region consisting of two subregions. The inner region has several holes, where boundary conditions are applied. The figure shows the idea. I have tried to create this ...
12
votes
1answer
162 views

RegionNearest and neighborhoods

In this previous question we see that RegionNearest isn't quite as 'capable' as Nearest for some things. Similarly, I need to ...
7
votes
3answers
370 views

Converting Mesh in Density Plots to a Graph

Consider the following line of code: ...
9
votes
4answers
662 views

How discretize a region placing vertices on a specific non-uniform grid

Given a generic region, for example: Ω = ImplicitRegion[ 2 x^2 + 3 y^2 + 2 x y - 2 <= 0 ∧ x^2 + y^2 > .1, {x, y}]; and a non-uniform grid, for ...
12
votes
1answer
526 views

Hexagonal Mesh on a 3D surface

I am new to Mathematica, and I am trying to create a 3D hexagonal mesh on a 3D surface. It is very similar to what was done in this post Create a torus with a hexagonal mesh for 3D-printing, but now ...
8
votes
2answers
567 views

How to use Mathematica to turn a picture into low poly style?

I want to use Mathematica to turn a picture into low poly style. That is, to make the following conversion: Bill to Bill low poly(Using Image Triangulator App). I think the biggest difficulty is how ...
7
votes
3answers
251 views

Lloyd relaxation on VoronoiMesh

How can we apply Lloyd's relaxation algorithm to a VoronoiMesh? Thanks. UPDATE Thanks a lot KennyColnago for your answer. Based on Simon Woods suggestion of ...
7
votes
2answers
1k views

How can I mesh a solid cylinder with triangular or tetrahedral elements

I need to plot triangular mesh on a cylinder. However the function Cylinder doesn't have a mesh option. By using ...
11
votes
1answer
276 views

How to specify PDE Boundary condition on Bspline?

Context I would like to solve a PDE on a boundary which is parametrized as a BSpline. I am trying to solve the force-free Grad-Shafranov equation on a ...
8
votes
2answers
137 views

How to assign Element marker at boundary edges

How to assign marker at the boundary edges as 1, 2, 3, 4 respectively and set all of the inside elements of region as 0? for example: Code: ...
6
votes
2answers
335 views

Join Two Element Meshes

Let's say I have two element meshes defined as the following: ...
5
votes
2answers
162 views

How to create a surface mesh embedded in 3D?

I am working on a problem where I want to optimize current densities on 2D surfaces embedded in 3D to generate magnetic fields. The current density on a surface can be written as a scalar function ...
5
votes
1answer
246 views

NDSolve and FEM support for non conformal meshes of a disk [with Kernel crash]

I want to create an ElementMesh for a disk. For my specific scenario, some author advise to use a regular mesh, where the radial and tangential directions are ...
8
votes
0answers
82 views

Why isn't ToElementMesh figuring out what my boundary is in 3D?

I am trying to change the element mesh for a FEA application I'm doing. I thought I understood it, when I did it in 2D. Here's my shape: ...
7
votes
2answers
173 views

Poor/wrong sampling in 1D DiscretizeRegion of splines?

Bug introduced in 10.1 and persisting through 10.2 or later Context In relation to this question I have would like to use splines to define a ...
6
votes
2answers
107 views

How to scale values for ColorFunction in SliceContourPlot3D?

Trying to help out in the question, Finite Elements 3D, I came across this behavior of SliceContourPlot3D: ...
5
votes
2answers
128 views

MeshRefinementFunction missing points

I'm doing some FEM on a rectangular region with a spherical cavity: ...
4
votes
1answer
106 views

Problem with MeshOrderAlteration to create a 2nd order ElementMesh

After working on this 2D domain, I'm trying to reproduce the same ideas to create a mesh of a sphere composed of QuadElement, instead of more simple and common <...
8
votes
1answer
407 views

ListContourPlot3D doesn't use all points

Edited thanks to @Kuba: In the following example, ListContourPlot3D accepts an array of points spaced at intervals 0.1 apart throughout the volume, but seems to choose an arbitrary number of points ...
8
votes
1answer
151 views

ParametricPlot MeshStyle bug in v10?

Bug introduced in 10.0.1 or earlier and fixed in 10.0.2.0 Original Post The documentation gives the following code and says "Use a red mesh in the x direction and a blue mesh in the y direction:" ...
7
votes
4answers
505 views

Change appearance of ConvexHullMesh

I'm struggling to understand the behaviour of ConvexHullMesh (or rather the non-behaviour). I have a polynom p ...
6
votes
1answer
132 views

Smoothing out data points in a ListDensityPlot

I stumbled upon this problem when I was trying to make some nice smooth ListDensityPlots of my numerical data. In short, my problem is that I let Mathematica plot two copies of basically the exact ...
6
votes
1answer
139 views

how to create a FEM mesh with “RegionPlot” where the sample points are a function of the position

I need to resolve the diffusion equation in a domain with circular sources (holes). I've tried defining the whole region with holes but the result is very mesh-dependent and not symmetric, so at the ...
3
votes
2answers
136 views

How to make the mesh to rotate with a surface in Manipulate?

Here's a Manipulate code to show a particular 3D surface, rotating uniformly in time. The point of this Manipulate box is to show that the surface do indeed rotate like a solid, so I can't "cheat" ...
3
votes
1answer
142 views

Increasing NDSolve computation range for 3D stationary PDE

I am trying to solve 3D Schrodinger equation (with mass equals to 1) and with no potential (I will add a potential later). My goal is to set boundary conditions on the outer boundary of a sphere and ...
3
votes
1answer
272 views

Writing loops for triangle elements

I'm kind of new to using Mathematica, so any help is great. I'm trying to write a program that will create a list or matrix that will give each small triangle's point numbers. For example if given ...
3
votes
1answer
206 views

How to calculate a Delaunay mesh nerve?

How to calculate a Delaunay mesh nerve? A Delaunay mesh nerve is a collection of triangles that surround a single triangle called the nerve nucleus. The triangles in a Delaunay mesh nerve either have ...
2
votes
1answer
171 views

How does one get Mesh lines at 0 in ParametricPlot3D?

The following is in the documentation (MMA 10) under ParametricPlot3D -> Options -> Mesh : ...
1
vote
1answer
67 views

Angles inside of Voronoi mesh cells

How can I determine the angles belonging to the vertices of each interior Voronoi mesh cell? ...