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schneik
Posts: 651
Registered: ‎04-05-2003

What a mesh

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08-12-2013 03:53 PM

 

OK, bad pun aside, Mesh is a passionate topic for me.  For quite some time it has been apparent that people are looking more and more to aggregate and mashup designs.  There are A LOT of 3D design tools out there. We have made good progress on getting translators for most 3D CAD tools so you can read these models into Fusion 360.  Increasingly there are desires to bring in data from visualization, reality capture and other sources. The challenge in doing this is in how the data is represented.

 

For years there have been 2 popular types of model representations:

  1. Boundary Representation aka BREP/Nurbs
  2. Polys aka Mesh models

BREP models are mathematical models that represent surfaces and solids with high precision.  They use these mathematical models to generate mesh information to render to your graphics card or to export to stl.  They can generate any level of mesh detail because the mesh is calculated from the mathematical model.

 

Mesh models are shapes created from polygons where the user is directly create the polys and can decide the mesh density required.

In the past few years sub-d modeling ha become popular as an evolution of mesh modeling as it allows mesh refinement automatically.  It is still a mesh representation and the output is a specialized mesh type.  To complicate things there are different mesh types. Typical meshes are made of three sided polys.  Some design tools can create meshes that are 4 sided polys. Affectionately called quads.

 

(I'm sure I am offending some since I am grossly simplifying some details here but for the sake of this post I will gladly take their ire)

 

So imagine you find a great STL model. It is a mesh model made of triangles. If you look at any hole or fillet you will see that it is faceted and made up of lots of triangles.  Now, suppose you want to use that in Fusion 360. You find one of any number of mesh to solid tools and you get a solid of some kind.  You open it in Fusion 360.  ITs never going to be the same as a design you created in Fusion. Each poly face has become a flat solid face.  There will be very little you can do with it.

 

So here is where are passion for this problem comes in.  This agregrtion and mixed modeling has been the vision all along.  Fusion 360 already has a good start on the problem.  TSplines technology has allowed us to take in Sub-d and quad mesh data and convert it to Tsplines data. Which in turn can be converted to BREP.

 

This winter we are going to add general support for Mesh data.  You can read in mesh data like STL, tinkercad or Sketchup.  You will be able to connect to Recap or other scan/photogrammetry tools.  Mesh data can have color and you can position and scale it. You will be able to snap to it and start creating new surfaces and tsplines on top of it.

 

After that we have ideas on converting tiangle polys to quad polys (called retopolization) or vice versa.  We have some exciting work on converting mesh to analytic geometry so those STL file holes that are all faceted can be automatically converted to cylinders.

 

Until then, you mileage is going to vary. Fusion 360 is best suited for Sub-d/nubrs/BREP modeling.  You can make Fusion 360 work with triangle poly data but it's going to be a hard fought battle untill we get some of the above enchantments in.

 

We really think we can be the best in class tool for working with all these different types of representations.  What you you think? Is this important to you?

 

Kevin Schneider


15" Macbook Pro Retina - OSX 10.9 in Portland, Oregon


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Active Contributor
LeonMF
Posts: 34
Registered: ‎02-14-2013

Re: What a mesh

08-12-2013 04:02 PM in reply to: schneik

Given my role in prompting this thread, this is important to me. :smileyhappy:

 

For me, there are two likely use cases.

 

1. I have access to a reference design, such as the X-Carriage for my 3D printer but I need to modify it.  With the current state of Fusion 360, that was a about 4 hours to painstakingly work with the mesh to generate a Fusion 360 clone and an hour to make my modifications once I was able do dispose of the mesh model.

 

Right now, one of my engineers is using tinkercad to patch up some custom Prusa i3 parts for the printer we're building.

 

2. 3D scanning.  I want to be able to 3D scan objects and build things around them.  For example, making a bracelet from a scanned wrist.

 

Those are both use cases you alluded to above.  I expect to need the second use case more than the first but who knows when I'll need what.

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*Expert Elite*
big_red_frog
Posts: 243
Registered: ‎03-02-2013

Re: What a mesh

08-12-2013 09:55 PM in reply to: schneik

Not having played with 3d modelling fot 10 years, and only dabbled back then, I don't know what I actually want, except ease of use, a good chance of a workable. Import and for she'll, snap to edge, point etc to work with models when they do import ( or less cryptic errors that give me a chance to fix them).

 

I am struggling through and finding ways to do what I need, but believe it's half my ignorance and half the maturity of the package.

 

Its a journey and I am going to stick with it.

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