How to model graphically complex shapes in matlab?

Hi, I need to model a complex 3D shape graphically so I could extract the analytical expression that fit the surface of the shape. Is there a way to do the modeling in matlab or I should work with STL files exported from a CAD system?

Answer 1

[michio]

I'd suggest that you generate a complex geometry using other CAD tool and exported it to STL if you want to import back to MATLAB. There are ways to create 3D geometry, Computational Geometry , but not sure how easy it is compared to some CAD tools.

Regarding the extracting analytic expression of the geometry surface, that seems to be whole another task. Do you have some expression you want to fit to?

[Inna]

Hi, thank you for the fast response. after I import the 3D shape into MATLAB, can I extract the 3D point coordinates of it? (If so, fitting an analytic expression could be done with fit function)

[michio]

Suppose you generated a STL file using some CAD tools, then you can try using functions from File Exchange,

ex. https://jp.mathworks.com/matlabcentral/fileexchange/51200-stltools

I haven't tested all the functions from File Exchange but the one above has a good reputation :)

Usually you can get the vertices, faces, face normals of the geometry from STL files, so 3D coordinates could be extracted.

If you are interested, importGeometry function from PDE Toolbox imports geometry defined by STL files into MATLAB.

[DGM]

Since R2018b, MATLAB comes with STL tools stlread and stlwrite. If you're running an older version, then I agree with the recommendation of FEX #51200 at the time it was made, but FEX #182013 includes significant improvements over #51200.