How do you convert a surf object to an isosurface?

Question

Kurt 2024-5-6

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2115721-how-do-you-convert-a-surf-object-to-an-isosurface

评论： Kurt 2024-5-16

How to convert a regular surf surface (rectangular mesh) to a patch isosurface (triangular mesh)?

I have seen how to go the other direction, but this one eludes me. After creating the isosurface, I need to run inpolyhedron() to see if points are inside or outside the object.

theta = (pi:0.1:pi);
phi = 0:0.1:pi);
[THETA, PHI] = meshgrid(theta, phi);
x = cos(THETA).* sin(PHI);
y = sin(THETA).*sin(PHI);
z = cos(PHI;
ellipsoid = surf(x,y,z);

(Extract the isosurface from the ellipsoid...)

fv = isosurface(something something ...)
pts = rand(5,3);
in = inpolyhedron(fv,pts);  % check if points are inside or outside object

2 个评论
显示无隐藏无

John D'Errico 2024-5-6

It is an ellipsoid though! It is far simpler to test if a point lies inside an ellipsoid, if that is all you need.

Kurt 2024-5-6

It's actually more complex than that. I bend and shape the ellipsoid to resemble a radar beam.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Yatharth 2024-5-14

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2115721-how-do-you-convert-a-surf-object-to-an-isosurface#answer_1457056

在 MATLAB Online 中打开

Hi Kurt,

You can use the "delaunayTriangulation" function, to convert the rectangular mesh to a triangular mesh.

for your given code, here is how you can use the function:

theta = (0:0.1:2*pi); % Corrected range for theta

phi = (0:0.1:pi);

[THETA, PHI] = meshgrid(theta, phi);

x = cos(THETA).* sin(PHI);

y = sin(THETA).*sin(PHI);

z = cos(PHI);

h = surf(x,y,z);

axis equal; % Equal aspect ratio for all axes

X = get(h, 'XData');

Y = get(h, 'YData');

Z = get(h, 'ZData');

% Flatten the matrices

x = X(:);

y = Y(:);

z = Z(:);

figure;

DT = delaunayTriangulation(x, y, z);

Warning: Duplicate data points have been detected and removed.
The Triangulation indices are defined with respect to the unique set of points in delaunayTriangulation.

tetramesh(DT, 'FaceAlpha', 0.3); % Adjust 'FaceAlpha' for transparency

axis equal;

You can refer to the "delaunaytriangulation" function documentation here https://www.mathworks.com/help/matlab/ref/delaunaytriangulation.html