[Tamar]

3D printing: skins vs bodies, meshes vs solids, squares vs triangles...Babylon rules
Oct 2018, on my hard disk most likely the most detailed 3D model of a BMW M8 GTE, as an extra the 3D Artist had thrown in a perfectly detailed interior.
So what now...press "CTRL P" for print? Well I knew it was not going to be that easy,  Fola had done projects like this before.
We knew that we would need another 3d specialist to convert the model into a 3d printable file. But boy was I in for a steep learning  curve.
Some of the members on SF are working with 3D designs and prints, but for those of you that have no experience at all...a short "simplified" introduction.
A kind of summary of the stuff I was about to learn the hard way,
 
A small introduction into the world of 3DP
If you want to create a digital 3D model there are basically two methods, two ways of doing this, you can work with skins and/or with bodies.
Working with Skins is best illustrated by thinking how, in the old days, a carrossier would use sheet metal to build up the outer skin of a car body.
For working with Bodies you could best think of a scratch builder, carving that same shape out of a solid block of balsa wood.
 

On the left: Aluminum skin shaped on a wooden buck to form the body of Daytona Coupe. On the right solid blocks of Jelutong wood to be cut back to form the body of a Tojeiro Climax GT
 
Meshes vs Solids
Skins are often referred to as meshes, like a wireframe, but unlike the metal skin of the Daytona Coupe they don't have any physical properties, no thickness.
They are but digital boundaries. For example to create a cube you need to mesh the 6 faces of that form a cube, the shape of the cube would be defined, but not its contents.
If you want to 3D print that "meshed" cube you need to convert the mesh into a Body, often referred to as a solid, because...well that's what they are after conversion.... solid.
In general "free form" 3d modeling like for Film, Animation and 3D Games use meshes, 3D modeling for fabrication of physical parts prefers working with solids.

Quads vs Triangles
So you would think that each 3d software program would have a simple drop down menu with a function "convert mesh into a solid". Well yes and no.
First of all there are many 3D software programs and again there's a two way division in how they construct a mesh... quads or triangles.
In general they're split along the same lines: Film, Animation and 3D Games use quads, Cad cam and 3D printers use triangles.
Quad meshes are better for "optical use" as they provide better and smoother renders, but they require more computing time and data.
Triangle meshes require less computing power 


On the left: the original M8 GTE 3d model, as you can see the mesh is build up by squares (quads) .  On the right an example on how quad mesh "renders" better than triangles.

Babylon rules
As you've probably guessed by now...that wonderfully detailed 3d model we got...had a quad mesh needing to be converted into a triangulated mesh before converting it into a printable solid body.
Like most computer programs destined to do the same work..they don't really like to talk to each other. Unless you have someone that really knows how to convert the one into the other...a lot of the data will one lost in translation and...Babylon rules
But as I mentioned  earlier, Fola had done these projects before, he had a guy that could do these conversions for us. So we send him the file and he said he would dig into it.
In for another waiting game, in the mean while I returned my focus to the BMW M6 that we'd been using as a test hack for the development of the M8 Chassis.


to be continued

With kind regards
Tamar