MATLAB: How to make delaunayTriangulation object from points and connectivity in 3D

delaunaytriangulationMATLABtetramesh

I am trying the tetramesh function. Before I plot the tetraheron mesh, I need to store the mesh in an delaunayTriangulation object. I have the points and connectivities. I coded as below.

DT = delaunayTriangulation();
DT.Points=node;
DT.ConnectivityList=elem;

But I found the error.

Cannot assign values to the triangulation.

In another way, "DT = delaunayTriangulation(P,C)".

DT = delaunayTriangulation(node,elem);

Came the error,

Invalid data format for delaunayTriangulation.

I think the connectivities must be 3 column for triangles, not tetrahedrons.

So, is it anyother way to create a delaunayTriangulation object for tetraheron to use tetramesh?

Best Answer

You should use the function triangulation for this. Read about this.

https://in.mathworks.com/help/matlab/ref/triangulation.html

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MATLAB: Mistake in delaunayTriangulation function

Those spurious triangles that got created have infinitesimal area.

In fact, IF I use the points you have supplied, I do get 18 triangles. But you have written out those numbers only to 5 significant digits, not the roughly 16 digits that MATLAB actually carries internally, so I cannot truly replicate what you did.

I've plotted the points you supplied. In fact, they form (roughly) a rectangular lattice.

To be honest, I'm not a big fan of using a delaunay triangulation on regular meshes, because it tends to produce a randomly oriented mesh. This is what I got from delaunayTriangulation.

The long, thin triangles that you got will typically be along the outside edge of that mesh. Here I've color coded the vertices from those two triangles with red * symbols.

plot(X,Y,'bo',X([1 5 9]),Y([1 5 9]),'r*',X([8 12 16]),Y([8 12 16]),'r*')

So, this really was not a "mistake", but just an artifact from bad data.

MATLAB: Find the vertices from delaunay triangulation

x = rand(10,1) ; % a randoms data 
y = rand(10,1) ;
dt = delaunayTriangulation(x,y) ;   % delaunay triangulation 
points = dt.Points ;    % points 
tri = dt.ConnectivityList ;    % nodal connectivity 
x = points(:,1) ;  
X = x(tri) ;
y = points(:,2) ;
Y = y(tri) ;

Best Answer

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MATLAB: Mistake in delaunayTriangulation function

MATLAB: Find the vertices from delaunay triangulation

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