Reverse engineering is a process of creating an exact 3D model of a real object. The process begins with 3D scanning and merging the scans together. Then these scans get post-processed and turned into a resulting model. This model can be 3D printed or used for further construction.

Reverse engineering is actively used in various industrial areas: from jewelry to huge projects in the aerospace sector, shipbuilding, or mechanical engineering. It is useful for re-creating  expensive and high-precision machine parts. However, it’s also a popular method for copying organic forms — for example, in prosthetics.

We continue our Reverse engineering for beginners series. This time we are going to show you how to perform reverse engineering of organic objects in Fusion 360.

Fusion 360 is a professional cloud-based CAD/CAE/CAM platform for manufacturing and product design. It unifies design, engineering, electronics, and production into an integrated software solution. Fusion 360 is frequently used by hardware startups, all kinds of innovators, and companies working with 3D scanning and 3D printers.

Fusion 360 allows you to:

• import 3D scans as STL or OBJ files and work with them;

• prepare models for 3D printing, automatically create supports for overhangs, and preview the structure of the parts;

• use a built-in CAM system to calculate optimal cutter trajectories and create parts using CNC machines;

• assembly any parts to test how movable joints behave — and much more.

Anyway, let’s focus on the reverse engineering functions of Fusion 360. In this article we explain how to:

• create a surface and align its edges;

• move the vertices of the surface closer to the mesh;

• stretch the surface to cover the entire mesh;

• fix any surface errors and adjust the surface;

• use the result to design a new object.

Every step of the process is illustrated with screenshots, and the entire process is shown on the video at the end of this article.

The process of reverse engineering in Fusion 360

We’ve chosen an actual human foot as an object for reverse engineering. The choice may seem random, but 3D scans of feet actually have many real applications. They are often used for production of customized prosthetics that fit patients perfectly well, medical research, and diagnostics.

3D scanners may also prove useful for designing shoes. Actually, that’s what we are going to do now. We will create a 3D model based on our 3D scan. Then we will use the result to design a perfect insole that will follow every little curve on our foot. Okay now let’s run Fusion 360.

1. We'll use T-Spline tools to create a CAD model based on 3D scan data (Create Form or SCULPT menu):

2. Let's use one of Fusion 360's primitives - Quadball. We need to define its center point on one of the existing planes:

3. The next step is to define its size and the number of faces moving the slider:

4. Then we align the Quadball and the mesh:

5. Let's hide the mesh and delete unnecessary faces of the primitive:

6. To be able to see our constructions inside the mesh we need to make it transparent:

7. We can align the edges of the surface using the FLATTEN tool:

8. With EDIT FORM we are able to move the vertices of the surface closer to the mesh:

9. It is necessary for the PULL tool to work properly (the tool pulls free vertices of T-Spline to fixed mesh vertices):

10. Then we stretch the surface with EDIT FORM creating new rows of vertices...

11. ...and use PULL again to align the new vertices with the mesh:

12. To add faces to our surface we use FACE with mesh snap:

13. The surface is changing while the tool is working:

14. Having selected necessary edges, we stretch the surface:

15. We use FACE again to build new patches to get a contour of the edges for stretching:

16. Not we can extend the surface, scaling and aligning the new row of vertices:

17. In the same way we cover the rest of the mesh and close the gap with the FILL HOLE tool:

18. Let's run REPAIR BODY to fix the surface errors automatically:

19. Use PULL to move some of the new points...

20. ...and move selected faces to cover the mesh completely:

21. We add new edges to get more control elements:

22. Moving them, we can adjust the surface to the mesh:

23. The wrinkles can be removed by deleting several control elements:

24. The surface is done. We will use it as a workpiece for an insole:

25. Let's use OFFSET to create a new surface based on the existing one:

26. We need two sketches to create a new cutting surface:

27. We use LOFT tool to create the surface...

28. ...and BOUNDARY FILL to transform closed space to solid:

29. Let's hide all the surfaces to see the body:

The results of reverse engineering

We have completed the reverse engineering process of the foot. As a result we’ve successfully created a precise 3D model based on our 3D scan file and used it to design a perfect insole. Now this insole may be turned into a customized shoe. And we will be able to repeat the process for other reverse engineering problems in Fusion 360.

Other articles in the Reverse engineering for beginners series:

FreeCAD: Reverse Engineering of Mechanical Forms

Geomagic Design X: mesh processing

Geomagic Design X: Reverse engineering of Organic forms

Watch the full video tutorial: