topic Bridging two models together causes them to unsmooth in Fusion Design, Validate & Document Forum

Bridging two models together causes them to unsmooth

Anonymous — Mon, 08 Aug 2016 14:27:41 GMT

I have two bodies that were both created using the model tool that individually have smooth/round edges. I've tried to connect the two bodies every which way I could (bridge, weld, merge edge), and in every case when I connect two vertices in one particular area in the middle - the models unsmooth, and turns into that jagged wire-frame look. Both bodies are pretty complicated, but the point of connection is pretty simple, with 8 edges on each side lined up near perfectly next to each other. Usually this happens if the bridge creates a model with self-intersecting surfaces, or broken twisted things, but that shouldn't be the the case here. I've tried hitting finish form to check for any self-intersecting surfaces in the models individually, and combined as one of those ugly wire frame things, and there weren't any. Is there any way to fix this/identify what's causing the connection to be unresolvable?

Re: Bridging two models together causes them to unsmooth

TrippyLighting — Mon, 08 Aug 2016 16:11:17 GMT

The best way to report this and get help is to make a screenshot or even screencast and even better, share your model.

Re: Bridging two models together causes them to unsmooth

PhilProcarioJr — Mon, 08 Aug 2016 17:21:13 GMT

@TrippyLighting is right we need at least a screen shot, but your problem can probably be solved with the face tool.

Re: Bridging two models together causes them to unsmooth

Anonymous — Tue, 09 Aug 2016 03:07:43 GMT

Thanks for your interest. Attached please find 3 screen shots, 1) the edges i'm trying to merge, 2) being able to weld all but 1 point with no issue; and 3) the result after welding the last point.

Re: Bridging two models together causes them to unsmooth

Anonymous — Tue, 09 Aug 2016 02:27:50 GMT

please see below for a reply in which I posted screens and the model! Thank in advance.

Re: Bridging two models together causes them to unsmooth

Anonymous — Tue, 09 Aug 2016 02:37:38 GMT

Thanks for the suggestion, but using the face tool yields the same results. I can create all of the faces except the last one you see here. As soon as I do that, it goes all blocky.

Re: Bridging two models together causes them to unsmooth

Anonymous — Tue, 09 Aug 2016 03:07:12 GMT

I figured it out! as I was welding, the models changed slightly, causing overlaps in the corners of the eye, using the repair tool and a lot of hunthing and pecking I was able to resolve all of them, and it returned to it's regular shape all connected!

Re: Bridging two models together causes them to unsmooth

TrippyLighting — Tue, 09 Aug 2016 10:25:38 GMT

While you might have been able to get you model to compute I am afraid that this is going to happen again.

The reason for that is that you are using triangles in your model. While you are getting away with that at the moment, this is likely going to bite you again.

T-Splines are happiest when you are avoiding triangles altogether. Triangles are evil! Quads and 5-sided polygons, but really mostly quads is what keeps your models stable with smooth surfaces.

Re: Bridging two models together causes them to unsmooth

PhilProcarioJr — Tue, 09 Aug 2016 12:09:02 GMT

@TrippyLighting

You couldn't be more correct...he is setting himself up for a massive headache down the road.....

Not to mention the curvature map for this model will be bad....

Re: Bridging two models together causes them to unsmooth

Anonymous — Tue, 09 Aug 2016 14:42:05 GMT

Thanks for the note, I had no idea. So what do you do when you need a triangle shaped face, do you just keep an extra vertex close to one of the legs of the triangle? I end up with these because i'll be trying to join some planes/faces that partially overlap, so I'll weld 2 of the corners of one of the face together.

Re: Bridging two models together causes them to unsmooth

PhilProcarioJr — Tue, 09 Aug 2016 15:15:17 GMT

@Anonymous

You will have to point out areas where you think you need a triangle and we can point you in the right direction. I have a little bit of experience with T-Splines in Fusion.

Another observation I made about your model is you are using the face modeling method used in polygon modeling apps....that too is a very bad way to work with T-Splines in Fusion.

Let me explain why....When you model with T-Splines in a closed shape the curvature is continuous across the shape. When you face model it is not because of the edge curvature controls...and although usually when you join T-Spline patches together, Fusion re-approximates the curvature correctly. But if the joining geometry is (for lack of a better term messy) the curvature is trashed and there is no real way to recover from this state. Based on the current topology of your mesh your going to have a lot of messy geometry. Your topology in a lot of areas does not flow with the forms, this adds another layer of problems with surface tension. So all in all your current workflow and topology = migraine headaches. I only tell you this because I have been there before and there is nothing worse then pouring blood, sweat, tears and life hours into a mesh that's harder to fix then starting over.

Just my 2 cents...

Re: Bridging two models together causes them to unsmooth

Anonymous — Tue, 09 Aug 2016 15:57:23 GMT

Thanks, I very much appreciate your observations - i'm just making this model to learn Fusion and see what I can make, so best practices are great to hear. How would you go about making a similar model? Should I be using different software?

I use a lot of triangles in radial areas such as the nose part. I've clipped a piece of the screenshot above that has a lot of triangles. Where you suggest a fourth vertex? Where I put the question marks?

Re: Bridging two models together causes them to unsmooth

PhilProcarioJr — Tue, 09 Aug 2016 16:25:18 GMT

@Anonymous

Just trying to help you out and save you some headaches. For stuff like this I find it easier and faster to make my quad meshes in Maya or blender then bring them in and convert them to T-Splines. Although this can be done entirely in Fusion. Which path you follow is up to you but IMO use what works best and gets the job done so you can make the next cool thing.

Here is a very rough and quick markup just to give you some ideas...at this point you should really go check out some youtube videos on modeling in quads. The theory and practices you will learn will push you forward 10 fold in no time.

Re: Bridging two models together causes them to unsmooth

Anonymous — Tue, 09 Aug 2016 16:32:00 GMT

awesome, thank you! I will do that.

Re: Bridging two models together causes them to unsmooth

PhilProcarioJr — Tue, 09 Aug 2016 16:37:57 GMT

@Anonymous

Your topology needs to be clean like this.....LESS faces though if your using just Fusion T-Splines.

Re: Bridging two models together causes them to unsmooth

Anonymous — Tue, 09 Aug 2016 20:26:26 GMT

Wow! that is indeed super clean! Is there any good way go back and clean up my existing model (like reset/straighten edges), and weld/cut new faces, or do i just need to be much more careful from the onset? I have noticed a bunch of bumps and aberrations in my shapes, so now I know why!