Questions tagged [mesh]
Questions on the use and creation of meshes including the use of MeshRegion, ElementMesh, and TetGenLink.
736
questions
1
vote
2
answers
27
views
How to create an ElementMesh with at least two triangle elements at each corner?
Based on this simple example of a triangle mesh
...
- 40k
1
vote
0
answers
48
views
RegionUnion looses MeshRegion's Markers
The following code shows the prescripted MeshCellMarkers 1 and 2 as expected :
...
- 17.2k
7
votes
3
answers
247
views
Fast Segmentation
Imagine I have an image of a segmented tissue as follows
what is the fastest way of converting such an image into a mesh-type object in Mathematica? I am familiar with ...
- 4,250
4
votes
1
answer
103
views
Steady state heat equation/Laplace's equation special geometry
I would like to solve the Laplace's equation in between the square domain and a disk. However, using the code below, I was able to generate mesh but not able to obtain results with correct boundary ...
- 63
2
votes
1
answer
87
views
RegionIntersection extremely slow before throwing error
I am dealing with polygons admitted by using other region functions (like RegionDifference), some of which have insidious problems.
Consider those below;
...
- 1,113
0
votes
0
answers
29
views
Crash when repeatedly calling RegionIntersection (and/or Mesh functions)
My kernel (v13.1.0 Windows 64-bit) crashes when repeatedly (~9 times) calling Region functions like RegionIntersection upon ...
- 1,113
2
votes
2
answers
107
views
3D FEM - How to define Point-Markers for an ElementMesh object created with ElementMeshRegionProduct
I want to create a 3D grid based on a 2D mesh, on the surface of which I want to assign point-marker for certain regions. The mesh created in the sample code is a fluidic Y-structure, at whose inputs (...
- 31
2
votes
2
answers
158
views
Region between finite lines or extracting a finite tesselation
EDIT2 the answers here (How to compute intersections of circles on a lattice) seem like they could help or solve the problem.
EDIT: I saw this question about finding regions between lines before I ...
- 3,397
1
vote
2
answers
150
views
Unify Polyhedrons into a single Polyhedron
Consider these two simple Polyhedrons which share a sub-face:
...
- 1,113
2
votes
0
answers
137
views
Packing triangles into a rectangle
I'm working on packing a set of triangles into a rectangle but I'm unable to get them to pack dense enough or even touch. I found a post from 3 years ago called "Packing arbitrary shapes" ...
3
votes
2
answers
183
views
4
votes
1
answer
86
views
Can't verify MomentOfInertia of a MeshRegion
In this simple modified(thanks @DanielHuber) example I create a volumemesh of a region
...
- 40k
0
votes
0
answers
45
views
Volume-mesh of a closed Surface-Region?
For an examplary given surface mesh (example from documentation DiscretizeRegion )
...
- 40k
1
vote
2
answers
75
views
How to find the regions corresponding to a given data set?
I have a data set corresponding to some problem. The data set is just a numerical sampling of $(x,y,z)$ where a particular formula is valid( this thing is analytically intractable that's why I ...
- 177
0
votes
1
answer
90
views
0
votes
1
answer
88
views
2
votes
0
answers
66
views
Bug of RandomPoint or Bug of Region?
Mathematica 13.1 on Mac
In the help page of RandomPoint, it says:
RandomPoint can generate random points for any RegionQ region that is also ConstantRegionQ.
The data of mesh is here
...
- 8,389
2
votes
1
answer
102
views
Pattern not matching BoundaryMeshRegion
Mathematica 13.1 on Windows 10.
Can someone explain why the following does not match:
MatchQ[BoundaryMeshRegion[Cube[]], BoundaryMeshRegion[__]]
(* False *)
- 32.4k
1
vote
1
answer
45
views
Draw Meshlines for specific z-coordinate and where x==y
I want to draw a Meshline where x==y and where z==4. The following code does neither. (The x==y line is horribly jagged and the ...
- 1,182
6
votes
1
answer
98
views
Create a domain for an Hexahedron with the floor replaced with an Indian Burial Mound
I am trying to create an acoustic model domain for a small park that contains an Indian burial mound.
The park is laid out using a 3D cartesian coordinate system in units of meters.
A Hexahedron ...
- 2,147
4
votes
0
answers
88
views
5
votes
0
answers
92
views
Why BoundingRegion so weak in such cases?
Each time, when I use FastCylinder option in BoundingRegion, I'll get this kind result. This problem lasts for many years, since ...
- 8,389
4
votes
1
answer
230
views
How to get the cross sectional area of a wine bottle picture/photo by doing an appropiate image processing on it?
We are working on a PDE Acoustic model in which the geometry of analysis
is the cross-sectional area of a wine bottle. We want to get the
geometry from a wine bottle image by doing an appropriate ...
- 41
4
votes
2
answers
124
views
1
vote
0
answers
66
views
Building a structure out of cubes one block at a time
I have simplified code in which the motion of a point charge is simulated N times (one particle at a time) in a static electric field. When the point charge comes to rest (using WhenEvent boundary ...
- 363
3
votes
2
answers
166
views
BoundaryMeshRegion Error: Boundary surface is not closed
I am trying to create a BoundaryMeshRegion comprised of many cubes with random locations, in a relatively small region.
I have had success implementing my technique for a smaller number of cubes (say,...
- 363
4
votes
1
answer
114
views
How to import and render this OBJ file with correct texture?
Here's the output of a 3D scan of a bike, I need to render it in color with the texture file provided. Here are the files:
...
- 30.9k
12
votes
0
answers
332
views
How to reconstruct 3d meshes from 2d images of a scene?
The new ImageStitch was nice functionality added in v13, but is there anything available for constructing meshes (with color textures) from a bag of 2D images (...
- 30.9k
6
votes
2
answers
231
views
Extract 2D quad mesh from 3D hexahedral mesh
I would like to extract 2D mesh of outer surface of 3D meshed object.
Let's say I have 3D mesh data from here and I import the data into Mathematica.
...
- 579
3
votes
2
answers
130
views
How to refine FEM mesh for steady state 1D problem?
I am solving a system of 3 steady state 1D ODEs, however the system consists of component that has sharp changes at x = 1, which is very hard to capture. Is there a way to specifically increase the ...
- 181
4
votes
1
answer
85
views
3D Mesh refinement near sphere boundary and on surface revolutions
I am trying to solve an advection-diffusion problem inside surface of revolutions. I have high velocity gradients near the boundary of the bounding surface. Is there a way to refine the mesh near the ...
- 75
3
votes
1
answer
87
views
Error Meshing with ToElementMesh (ToElementMesh: Cannot set region holes.) for certain objects
I have had a problem properly meshing certain .obj files, where others are meshed successfully.
Here is an example of a successfully meshed .obj:
Whereas, using the code at the bottom which includes ...
- 363
2
votes
1
answer
65
views
RegionDifference Fails at Two Simple Cubes
Or, maybe, I just dont get it right.
I got two simple mesh cubes:
...
- 303
3
votes
1
answer
75
views
Keeping mesh coordinates unchanged for Implict Region [duplicate]
I am trying to generate a 3D mesh for Finite Element simulations. I need to provide some precomputed inputs to the mesh points and will like my mesh to be the same for a given shape. However, ...
- 75
4
votes
1
answer
127
views
Finding sub-regions in an STL file for Finite Element
I use an external software (Amira) to segment X-ray tomography images and then create a surface mesh which I can then import into Mathematica as an STL file. This file has two enclosed regions, ...
- 3,660
0
votes
1
answer
106
views
Finite Element NDSolve with input data at node points
I am trying to solve a steady-state advection-diffusion problem of the following form:
$-D \nabla^2 T + \nabla \cdot (\mathbf{u} T) = -1$. I will be solving this problem in a 3D geometry (typically ...
- 75
2
votes
1
answer
65
views
3
votes
1
answer
187
views
Generating a non-convex polyhedron from polygons and normals
I am working on developing "directional offset" module, which requires pretty tricky mesh generation: offset values vary in different directions.
Suppose I have list of points and polygons, ...
- 303
1
vote
1
answer
194
views
Properly Updating Particle Motion in 3D Electric Field Simulation
I have a code (very bottom of post) which plots a static electric field as it passed through some metal sheet with an aperture in it.
I seek to observe the motion of some N charged particles (point ...
- 363
0
votes
1
answer
60
views
3D Parametric Plotting for N Charged Particles in a Nonuniform Electric Field
I have a code (very bottom of post) which plots a static electric field as it passed through some metal sheet with an aperture in it.
I seek to observe the motion of some N charged particles (point ...
- 363
0
votes
0
answers
62
views
Meshing Error on Imported obj file
I am trying to import a .obj file to be used in a static electric field simulation. I am able to successfully run the simulation with certain other aperture geometries (see here: < https://www....
- 363
6
votes
2
answers
247
views
Coarse mesh of a sphere
I try to mesh a sphere (examplary) in different qualities, using MaxCellMeasure:
...
- 40k
4
votes
2
answers
213
views
Finding Mesh Cell Normals
I need to find a normal pointing outside for every face / cell of a closed Mesh Region.
How can I do this?
Here's what I have now - mesh + mesh cells centers and I'm stuck and puzzled.
There's ...
- 303
3
votes
2
answers
103
views
Defining Dirichlet Boundary Conditions on an Imported 3D Object with Apertures in it
I am trying to simulate a static electric field (in 2d and 3d) as it passes through a couple of apertures in a 3D "metal sheet" (model imported as a .obj file) given here:
https://www....
- 363
1
vote
0
answers
42
views
Meaning of MeshCells for CantorMesh?
Let
cantor2 = CantorMesh[2]
As expected:
RegionBounds[cantor2]
(* {{0., 1.}} *)
And as expected:
...
- 11.6k
0
votes
0
answers
73
views
Difference between a region and its convex hull
I have a volume enclosing a certain region. The region is non-convex, and I calculate its convex hull with the built-in Mathematica function. I want to know the difference between the region and its ...
- 125
3
votes
1
answer
101
views
Is it possible to solve a differential equation with a user-defined variable mesh in NDSolve?
For some differential equations, its solution may evolve to a cusp, for example, singular behavior. One may want to introduce additional mesh points near the cusp to accurately follow the solution ...
- 93
8
votes
3
answers
359
views
How to generate a mesh in an area with curves inside
I would like to know how to generate a mesh inside an area, and be able to find the original curve outline inside the area from the mesh.
For example:
There is a rectangle inside which there is a ...
- 83
4
votes
2
answers
198
views
For "RegionPlot", how to fill lines, points, or grids in different areas?
For "RegionPlot", how to fill lines, points, or grids in different areas?
I have tried "Mesh", but it fills all region in same mesh.
I want to get the result just like this picture,...
- 41
8
votes
1
answer
222
views