Confusion over export options

[welbot]

I was just working on something, and I wanted to export one body as an obj or fbx to check the mesh version in another software package, but it seems the only way I was able to do it, was to first create a component from the body, then "Save copy as" to save that single component in to a project of its own, which I then loaded, and via the main file menu at the top, selected "export" and then chose FBX/OBJ. 

Is there a particular reason why when you right click on a body and choose export, that the only options are for CAD formats? Even changing the body in to a component of its own, and trying to right click and export the component  only allows CAD formats. The only method that does allow for non cad formats, is the main file menu at the top, but it exports the entire project rather than just the single body I want exported.

If there is a particular reason, I'm keen to hear why, as I just find it a bit odd. If there's no particular reason, is it likely to be changed in a future update?

I can export an STL by right clicking on a body, so why not OBJ or FBX? I understand it needs to be "translated" via the server, but I assume it has to do this due to the fact it's converting an entire project hierarchy. Wouldn't it really be less work for it to translate just the body? If STL can be done without translation, isn't it possible to do the same for a single body in OBJ or FBX? 
Also, while I'm asking about it, I might as well throw in, will it ever be possible to export either of those formats as quad meshes? Other software allows for OBJ to be exported as tri's or quads depending on the option you choose. I would LOVE to see that as an added option!! 

[dsouzasujay]

Hi @welbot ,

I can't answer all of your questions but can answer some of them.

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Is there a particular reason why when you right click on a body and choose export, that the only options are for CAD formats? Even changing the body in to a component of its own, and trying to right click and export the component  only allows CAD formats. The only method that does allow for non cad formats, is the main file menu at the top, but it exports the entire project rather than just the single body I want exported.

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The reason is, 3rd party CAD formats need translation, Fusion 360 does translation on cloud.

 THIS forum thread talks about cloud translation advantages.

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I can export an STL by right clicking on a body, so why not OBJ or FBX? 

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Today its possible to export a .obj file directly from Fusion 360.

Again FBX needs translation.

Video Explains how:https://knowledge.autodesk.com/community/screencast/f109d78b-6772-460d-a730-10b741703297

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Will it ever be possible to export either of those formats as quad meshes? Other software allows for OBJ to be exported as tri's or quads depending on the option you choose. I would LOVE to see that as an added option!! 

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Today Fusion 360 supports Quad mesh export if you create a design in Sculpt/Form environment.

Today for Design workspace we don't have support to export Quad meshes, but we do have support for tria mesh.

Let me know if i have missed any part, i will tag someone experienced who can answer.

[welbot]

Hi Sujay,

Thanks for that link showing the export to obj. That's not something I would have ever considered trying in an effort to export a particular file format 😂  The FBX portion of my question isn't terribly important to be honest. It's just one of the two formats that Fusion can export that I can use, and I happen to know both support quad meshes. 

Speaking of which, my asking about the quad meshes, was specifically with regard to solid bodies being converted to be exported. I am aware of the 'forms' and I do in fact use them, but that's also part of the reason I was hoping to get a quad mesh out of the solid/brep part of Fusion. I often need to take things in to other packages at some point, to either accomplish something that's just not possible in Fusion, or to match up with other parts of what I'm working on that can't be brought in to Fusion. 
Once I'm done with what I need to do there, I often have to bring it back in to Fusion to continue working on it, and as I'm sure you will know, trying to do anything in Fusion with an imported tri mesh that's then converted to a brep, is an absolute nightmare, or potentially not even possible, as Fusion may just completely crap its pants if the triangle count is too high. 
So my hope is, that if Fusion can generate a quad mesh to export as an OBJ instead of a tri mesh, I can do work on it elsewhere, and then bring it back in to Fusion, and convert to a t-spline, and from there, back to a b-rep. 

Surely making a quad mesh couldn't be that hard. The meshes it produces for obj's and stl's etc., are 99.9% of the time, quad meshes, except they have the dividing edge between 2 corners of the quad, making it a tri mesh. Surely it must be possible to simply not output those dividing edges?

[jeff_strater]

Fusion can not export a quad OBJ mesh from BReps.  You can export a quad mesh from T-Splines (assuming that you created those T-Splines using only quad faces) using the "Save Control Frame as OBJ" command:

"Surely making a quad mesh couldn't be that hard".  Actually, it is quite hard.  There is extensive research around "re-topologizing" in the mesh world.  The application Instant Meshes does a decent job of it:  https://github.com/wjakob/instant-meshes for curvy, "organic" shapes.  You can export as STL and use Instant Meshes to convert to quads.  Sharp edges will probably be a problem.  There are other tools around with varying degrees of success, but it is not just as simple as combining every other triangle in a triangle mesh into a quad face.

[welbot]

Hi Jeff,

You can export the entire project as an OBJ though, and since STL is there on each menu for bodies, I didn't get why OBJ wasn't I was indeed aware of the t-spline method, but I am really hoping it may be possible for b-rep too. Normally, when I hit these issues, I have started my design as a b-rep because the tools are much more suited to the job. If I was able to convert the b-rep to an accurate t-spline representation of the body with ANY amount of ease, I wouldn't be fussed. 

The conversion process for b-rep to t-splines is just a nightmare though. One patch at a time, which never seems to be capable of matching/filling the space occupied by the b-rep face.. it's horrid!

I do tend to work with some odd shapes, and you'd think some of them might be easier to start as a t-spline to begin with, but I just can't achieve the same results and accuracy with it. For the most part though, I start these things with no intention of moving them to a different package until they are finished. It just  happens that I either hit a roadblock for some reason or another, or occasionally have a great idea for a design change part way through, and I just need to  make that change in something else. 

Given how nicely even the face distribution is in the meshes Fusion outputs, in theory, it shouldn't be terribly difficult to just tell it not to put the diagonal edge between each pair right?  Obviously it's not always foolproof  that a model will result in a pure quad mesh, but like with exporters from other programs, I'd much rather have to go through and manually adjust a handful of triangles, than be faced with what can essentially be a roadblock. 🙂

Even the quad meshes exported from a t-spline body, are still technically made up of triangles, they simply don't have a visible diagonal edge, hence my querying if it might be possible to include that functionality for the solid/b-rep bodies as well 🙂