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Monday 21 January 2019

Tailors dummy for 3D modelling

I have decided to model a costume helmet. To help with that I have been looking for a full scale model of a human head to use with Fusion 360. I could not find one I was happy with, so I created my own.

One of my main requirements was that it should not impact the performance of Fusion 360 too much. The thing I am creating is the important bit, not what I am modelling it round.

Too many polygons

All of the human 3D models I found are meshes and they are either poor quality or have too many polygons!

Fusion 360 is designed for solid body, not polygon mesh, modelling. Ideally I wanted a native Fusion 360 'Brep' model not a mesh.

I have eventually managed to convert a human body mesh, produced in MakeHuman in to a reasonably tidy 'Brep' solid body model for use in Fusion 360.

It took me the best part of Sunday afternoon with trial and error to get to an end result I am happy with. Fusion 360 can easily convert a solid mesh to a 'Brep' in one go but the result is poor quality and low performance.  The trick is to be able to convert it to T-spline first, to get rid of the reliance on the polygon forms.

The process, that eventually worked, was:
  • Create a generic gender neutral average human in MakeHuman
  • Save that as an '.obj' file
  • Import that in to Blender (2.8 beta**)
  • Get rid of the internal eye sockets and mouth
  • Seal up the eye holes and mouth to make a closed mesh
  • Create a sub-division surface mesh. This was the important bit.
  • Save as another '.obj' file of the higher resolution 
  • Import in to Fusion 360
  • Convert the mesh to T-spline
  • Convert the T-spline to Brep
  • Create the eyes from proper sphere's in Fusion 360 and join to the main body mesh.

Now I have a good quality mannequin model that does not significantly impact performance.

The sub-division surface in Blender creates an all Quad mesh. The use of Quads NOT triangles, was important to get a clean T-spline model in Fusion 360. It did not matter what number of sub-divisions, just one was enough to force the result to quads.

The better looking eyes are a nice to have. I could have done the same process on the MakeHuman generated eyes, as I did on the body. Then I would have ended up with facsimiles of spheres instead of parameter generated spheres.

I will scale the model, as required, to the approximate size for the costume I want to model.


Gender neutral human - body dummy (STEP format in zip file)
Gender neutral human - head dummy (STEP format in zip file)


** As a side note, the new interface, in Blender 2.8 beta, is so much nicer and easier to use than the earlier versions. It's close enough, to the earlier versions, that I could transition quite quickly but improved in many areas to make it more intuitive to use.