"Smooth" feature adds faces but there is no visual difference

[Anonymous]

I made a model for 3D printing in Fusion 360 and it has very noticeably not-smooth circular cutouts. I thought to import it to Maya and use the Smooth function on it but all it does is add faces, it doesn't change the positions of vertexes or anything to make it look more high-detail. This function has always worked fine for me, but I've been working on this for a long time and have not gotten anything to work.

When the object is selected, it is apparent that many more faces, edges and vertexes exist after the smoothing. I have attached screenshots of the mesh selected before any changes, the mesh selected after a smooth with 2 divisions, and the mesh deselected after the smooth. It's easy to see that even after the smooth, the object has a low-poly appearance, even though the outline of the faces would show otherwise.

As stated above, the mesh was created in Fusion 360. I exported it as an STL file and imported that to Maya. I need to export this back to an STL when I'm done making it look better so I can slice it in Ultimaker Cura. Also, it is worthy of noting that I would like to know how to fix this in Maya and I don't want a fix where I would somehow make it export higher quality in Fusion or smooth it in Cura. I should note as well that the smooth previews (2 and 3 hotkeys) don't show any difference even when the model is selected.

I'm using Maya 2019 on Windows 10 64 bit, and if you need it to help diagnose the problems, my system specs are:

AMD Ryzen 5 1600 6C 12T @3.8GHz all cores at all times

Overclocked nVidia GTX 1060 3Gb (I don't remember which exact model, but it's from EVGA)

B350 motherboard

16GB non-ECC DDR4 RAM

and a way bigger power supply than what these parts need.

[osidedan]

Hello! I think what is happening here is the mesh you are importing doesn't have the vertices merged. To fix that, simply select your low resolution import, then go to Edit Mesh > Merge. (you may need to adjust the tolerance settings if it merges vertices you don't want merged). After that though, you should be able to smooth it as you would expect. Hope that helps!

PS, here's a quick example of what I'm talking about. These 3 cubes have had their vertices split on purpose where the red circles are, and you can see the smoothing result next to them. What you have seems to be the example on the left, so doing a Merge should fix that:

Edit: Quick side note, one thing to keep in mind though when you go back to the other programs: Maya is a SURFACE modelling software. So when you go back to Fusion or some other SOLID modeling software, you will have to convert the model back to a solid object for printing. Shouldn't be a problem as long as you keep the Maya version of the model watertight. 

[Anonymous]

Hi, osidedan! Thank you very much for the reply! I tried this solution, but it made my model look weird and I don't quite understand what's going on or how any of this works with the merging and what it does. I took more screenshots and I hope they can help you.

From my understanding with the way you described it, when I imported the STL from Fusion 360, some data relating to the vertexes was missing, but I don't quite understand it or even know if that's right. I used the Edit Mesh > Merge tool, and with different tolerances the results were different, but it gave my model a weird shape and  when I smooth the model it only gets worse. Here is what it looks like before the merge:

And after the merge, it gets these things that look like dents, and are not extremely noticeable but definitely there:

And after a smooth, the dents look like wrinkles, and they are all over the place:

I was wondering if maybe I was doing something wrong, or if there could be something else going on, but I also was wondering if you could explain how and why all this happens. Sorry I'm a bit of a beginner and don't have a lot of knowledge, but your help is very much appreciated!

Thanks in advance!

[Anonymous]

To add, I don't know if this helps to know what's going on, but I've tried a whole lot of things and none of Maya's automated processes will change the original geometry. I've done MEL commands polyRemesh and polyRetopo (retopo didn't do anything the one time it didn't freeze up), I've done Mesh > Reduce, even Mesh > Quadrangulate, and all any of them do is add edges and faces to the original thing, preserving its original edges. And the reduce only subtracts from the product of that to get back to the original topology. I have tried softening all of the edges and it had no effect.

Hope that information helps!

[damaggio]

Hi Preston,

the solution is very simple , your mesh is not a subdvision model , it does not have proper topology for smoothing, you need to retopo or refine to high resolution in fusion for export to printing.

[Anonymous]

Hi, thanks for the advice! I am still somewhat a beginner, and I don’t know much about retopologizing. I’ve been trying to run the MEL command polyRetopo but it gets frozen at 66 percent for a while, then does it again at 83 percent. I left it on overnight even, and it didn’t get past the 83 percent. I have tried this with and without running a polyRemesh command, and have had the same result. Could you possibly explain or link me to something that would teach me how to retopologize without doing a lot of manual work?

Thanks in advance!

[damaggio]

The retopo tool is not gonna fix the mesh the way you need and  retopo by hand with the Quadraw tool is not gonna be easy for a beginner and you still need to understand subd topology and edge flows. 
The easiest way is to finish the piece the way is meant to look like for printing in Fusion,  don’t worry too much about having a high poly model in the end. Just go on to printing the piece.

[osidedan · Accepted solution]

What damaggio mentioned is 100% correct, the original topology isn't really suited for smoothing. In my original response I should have clarified that I was just elaborating on why it wouldn't smooth haha. 

Anywhoo, in the interest of getting this working for ya and saving a ton of work, I would just clean up the edges in Fusion, and skip Maya all together. Especially since this is going to 3D print. I've never used Fusion, but I downloaded the trial and after some tests it looks like you just need to add fillets to your edges that you want "smoothed".  Here's my quick mockup I did in Fusion of what I think you are after:

Let me know if that works, and I'll try to answer any questions with my limited Fusion knowledge haha, but the folks over in the Fusion forum will probably have a ton more info on the topic. Hope that helps!

P.S. outside of this project, if you are interested in hard surface modelling in Maya, there are TONS of tutorials out there. Just do a search for "maya hard surface modelling" or something like that. Same thing for retopology tutorials. Cheers!

[ThomasPasieka]

You may want to use the Soften/Harden Edges commands in Maya for this. Unless, you want to actually get a bevel in that circle. Then you'd need a bit cleaner topology for starters.

[Anonymous]

Okay. I am very interested in Maya, so I will definitely look up tutorials on the subject to learn more about the program and 3D modeling in general.

Also, a quick note, I already had the fillets on the edges, I just wanted a slightly higher poly/quality model than what Fusion exported.

Thanks to everyone for all the help! I hope y’all have a wonderful new year.