How to export a 3D surface (gyroid) as an stl file

Hi,

I'm a final year Mechanical Engineering student and for my final year project I'm studying the deformational behaviour of gyroids under several loading conditions. Currently I have managed to create a the gyroid's surface but I'm struggling to export the surface as an stl file. I've tried using the stlwrite function but it gives an error message saying "Input argument must be a triangulation object". I then tried to triangulate the gyroid surface using several methods but was unsuccessful. Here is the code:

clear all
close all
clc

x_period = 4;
y_period = 4;
z_period = 4;

% Setting meshgrid
[x, y, z] = meshgrid(0:0.1:x_period*pi, 0:0.1:y_period*pi, 0:0.1:z_period*pi)

% Gyroid equation
v = cos(x).*sin(y) + cos(y).*sin(z) + cos(z).*sin(x);

figure(1)
isosurface(x,y,z,v)
axis equal
xlabel ('X')
ylabel ('Y')
zlabel ('Z')

hold on

Any idea how I could save this figure as an stl file?

Thanks

[darova]

Read how to use isosurface (extract faces and nodes)

[迪迪 赵]

I have the same problem. Have you solved it? Can you tell me how to solve it? thank you!

Answer 1

[Henrique Ramos]

Dear Daniel

Use the stlwrite export (file exchange), find for download at,

https://www.mathworks.com/matlabcentral/fileexchange/20922-stlwrite-write-ascii-or-binary-stl-files

set the .m file at the same path, and run this code, at the your .m (gyroid)

fv = isosurface(x,y,z,v);

stlwrite('Gyroid.stl',fv)

[Oguzhan Arslan]

Can you explain with video or document?

I can't work systematic of matlab code.

Thanks

[MITHILESH KURUP]

Hello Henrique

I have tried to the same as you have suggested above. But no luck, I'm getting an error as below:

Unable to write to Gyroid.stl

Could you please let me know what might be the issue?

Thanks

[Henrique Ramos]

The code is simple like that, and the main thing is the file stlwrite from the link, as I mentioned, should be in the same folder.

Use the stlwrite export (file exchange), find for download at,

https://www.mathworks.com/matlabcentral/fileexchange/20922-stlwrite-write-ascii-or-binary-stl-files

% Number of cells
x_period = 4;
y_period = 4;
z_period = 4;

% Mesh grid
[x,y,z] = meshgrid(0:0.1:x_period*pi, 0:0.1:y_period*pi, 0:0.1:z_period*pi);

% Gyroid Isosurface
f = ((cos(x).*sin(y))) + ((cos(y).*sin(z))) + ((cos(z).*sin(x)));

% PLot Figure 
figure(1)
isosurface(x,y,z,f)
axis equal
xlabel('X')
ylabel('Y')
zlabel('Z')

% Name STL and write
stlwrite('Gyroid.stl',isosurface(x,y,z,f))

[MITHILESH KURUP]

Hello Henrique,

The file stlwrite from the link and the main code, both are in the same folder only.

But, unfortunately it is still giving the same error as before:

Unable to write to Gyroid.stl

The version that I'm using is MATLAB R 2021 b. Could it be due to the current version that I'm using?

Thanks

[DGM]

The given error message indicates that you're trying to write somewhere where you don't have permissions, or you're trying to overwrite a read-only file.

Unless you want to use some of its particular functionality, there isn't a need to complicate things by using FEX #20922. The problem with recommending it is that it will shadow the built-in stlwrite() that's already available in modern versions. If you want to use it, I recommend renaming it to avoid problems.

% ... all the plotting stuff

% you can either call isosurface() again, 
% or you can get the existing FV data from the figure.
FV = isosurface(x,y,z,f);

% FEX #20922 accepts multiple input formats
% it can accept F,V lists, an FV struct, or simple gridded data
stlWrite('Gyroid1.stl',FV) % i renamed this to prevent name collision

% built-in stlwrite() (R2018b or newer) accepts triangulation objects
T = triangulation(FV.faces,FV.vertices);
stlwrite(T,'Gyroid2.stl') % you already have this

I should point out that in the end, the given code will produce a surface, not a solid volume. It has no thickness, so depending on what you want to do with it, it might not work as you need it to.

Answer 2

[DGM]

See the full example here:

https://www.mathworks.com/matlabcentral/answers/1732640-how-to-export-a-3d-surface-gyroid-into-an-stl-file

This example produces a closed model, but it simplifies if you only want an open shell.