To generate vertice mesh from a series of contours

Hello,

As beginner in MATLAB, now I have a series of contours, which define a structure. On each contour there are isolated points whose cartesian coordinates are known. Now I would like to generate a mesh from these contours (or points). The MyRobustCrust.m from file exchange does generate a mesh with faces, but without vertices' coordinates. And the vertices are needed for my calculation.

Does any one have any hints? Thank you very much.

Erhong

Answer 1

[Sarah Wait Zaranek]

I believe this should work for you.

% Generating some contour data

x = rand(100,1)*4-2;
y = rand(100,1)*4-2;
z = x.*exp(-x.^2-y.^2);

scatter3(x,y,z,'b','filled')
hold on

% Calculating Triangulation
 dt = DelaunayTri(x,y,z);

% Finding the surface boundary 
[tri xf] = freeBoundary(dt);

trisurf(tri, xf(:,1),xf(:,2),xf(:,3), ...
     'FaceColor','cyan', 'FaceAlpha', 0.8);

% Getting the vertices

t1v = xf(tri(:,1),:); %x,y,z for first point in triangles
t2v = xf(tri(:,2),:); %x,y,z for second point in triangles
t3v = xf(tri(:,3),:);  %x,y,z for third point in triangles

vert = [t1v; t2v ;t3v];

scatter3(vert(:,1), vert(:,2), vert(:,3),'g','filled')
hold off

Answer 2

[Jiexian Ma]

If you plan to work with 2D finite element mesh, the following methods may be helpful.

• Method 1. Create geometry from contour vertices via Constructive Solid Geometry and obtain mesh via PDE toolbox. Darova's answer used this method.
• Method 2. Create geometry from contour vertices via polyshape and generate mesh via Im2mesh package.

Personally, I perfer method 2 because you can edit polyshape object easily.

Matlab code

You could check demo14 to demo17 in Im2mesh package. I provide a few examples.