topic Re: Modeling complex/compound curves in Fusion Design, Validate & Document Forum

Modeling complex/compound curves

Anonymous — Mon, 27 Apr 2020 00:14:13 GMT

Essentially what you see in the picture is an object with known dimensions with modeling clay added to fit constraining parameters. I have also modeled the object with known dimensions in Fusion 360 and have created alterations to it.

I have attempted to model the object from top, side and front pictures within Sculpt/Form. The top, side and front pictures included a grid overlaying the physical object to help express the curves. I am not getting accurate results. I am curious to know how you would model this?

I have also used photogrammetry to create an .obj file and will clean it up in Blender or MeshMixer. I just downloaded MeshMixer last night and have yet to dig in. The current plan is to take the cleaned up model, cut it where the plastic and clay meet and join it to the new dimensional piece I have modeled. I assume this can be done?

I have tried to convert the .obj file to a BRep, but Fusion didn't want any of it

Is it possible to use an .obj file/mesh as a form/boundry to either "fill" or use as a constraint while sculpting?

I know it would be an immense amount of clicking, but is it possible to trace the .obj mesh and utilize the traced model for further alterations?

At the end of the day, I'd prefer to just model the entire object and eliminate all these extra programs.

Curious to hear your thoughts and thanks for the help!

Re: Modeling complex/compound curves

laughingcreek — Mon, 27 Apr 2020 01:40:22 GMT

can you post the other pictures? it helps to put them in the body of your post

is the .obj a quad mesh or triangulated?

Re: Modeling complex/compound curves

Anonymous — Mon, 27 Apr 2020 02:39:15 GMT

Unfortunately, the .jpegs are too big to include on the body of the post.

It is a quad mesh.

Thanks! 🙂

Re: Modeling complex/compound curves

TrippyLighting — Mon, 27 Apr 2020 14:26:19 GMT

Import the quad mesh into Fusion 360 using Insert->Mesh.
Create a new Form.
While in that form environment, select the mesh and right-click on it.
Convert from mesh to T-Spline.
With Utilities-> Repair Body, check if there are any red points. Use auto-repair if there are any.
Click on Finish form.

You should now have a surface body or solid body in the browser.

Re: Modeling complex/compound curves

Anonymous — Tue, 28 Apr 2020 01:50:39 GMT

Thanks for the info, I will give that a whirl.

I went down the youtube rabbit hole last night and found some other interesting ways.

"Using convert and pull to match a mesh in Fusion 360" - https://www.youtube.com/watch?v=S_G_xs0Qx3c

"Reverse Engineering Meshes | AVA: Fusion 360" - https://www.youtube.com/watch?v=SykRF0C_MPo

Re: Modeling complex/compound curves

TrippyLighting — Tue, 28 Apr 2020 06:42:31 GMT

Those are workflows concerned with triangulated mesh geometry. You won’t have to mess with that if you already have a quad mesh.

Re: Modeling complex/compound curves

Anonymous — Tue, 28 Apr 2020 18:13:21 GMT

Awesome, it worked!! I had to reconfigure the amount of faces on the quad mesh, but I think I might have something usable now. I am not sure what the official quad face limit is, but Fusion just converted just over 168K quad faces into a t-spline model. I appreciate the help.

Re: Modeling complex/compound curves

TrippyLighting — Tue, 28 Apr 2020 18:30:37 GMT

The object in your images looks so simple that this should be possible with factor 1000 fewer quad faces.

Unless you want to convert every little surface pimple into actual geometry.

Re: Modeling complex/compound curves

Anonymous — Tue, 28 Apr 2020 18:57:49 GMT

I see your point. I did try to reduce the amount of vertices and faces but the surface/mesh starts turning "blocky" with sharp edges. So the curves aren't as smooth of an arch. I did try to smooth the mesh but only to have a message with something the like of "the surface is already smooth".

Re: Modeling complex/compound curves

TrippyLighting — Tue, 28 Apr 2020 19:01:45 GMT

How did you model that mesh in Blender ?

The only modeling tools in Blender that create such an amount of faces are the sculpt tools.

But those great triangulated faces.

Are you aware of the Subdivision Surface modifier?

Re: Modeling complex/compound curves

Anonymous — Tue, 28 Apr 2020 19:37:09 GMT

Here is a brief workflow breakdown:

1. The photogrammetry model had a few surface ridges which were smoothed using the sculpt tools in Blender. (smoothing brush)

2.) I cut clay cone (pictured) from the "plastic" body/base (not pictured).

3.) Deleted everything except the clay cone.

4.) Decimated the surface to .5 and exported out as a triangulated mesh, as I could't get Blender to create a true quad mesh.

5.) Imported the clay cone .obj with the triangulated mesh into Instant Meshes and converted it to a quad mesh.

6.) Converted the quad mesh using your information to t-splines

7.) Current goal now is to re-scale the clay cone and combine/mesh it into the new/modified "plastic" body in Fusion

I'm thinking I should have re-scaled the cone in Blender though.

I am unfamiliar with Subdivision Surface modifier, but I will look into it for sure.

Re: Modeling complex/compound curves

Anonymous — Wed, 29 Apr 2020 02:43:14 GMT

Well not sure why I thought that was going to work! 😄

T-spline bodies and BRep bodies don't merge *puts a check in the box*... the only thing I can think of is convert the BRep body faces to a T-spline and hand sculpt each face to the cone?

Is there a way to use the T-spline cone to reshape/conform the BRep body?

Thanks!

Re: Modeling complex/compound curves

TrippyLighting — Wed, 29 Apr 2020 16:05:45 GMT

Can you share the scan data?

I believe you are using a lot of cool technology perhaps following online tutorials such as this one, but don't really know whats going on under the hood and as such are somewhat blindly fondling your way forward 😉

As I've already mentioned for the simple shape of this object you should not be using more than 100-200 quad-faces when using InstanMeshes. Properly manually re-topologizing this perhaps with RetopoFlow might yield even fewer polygons and much better edge flow than a semi-automatic remeshing method.

Once that is achieved, I am not sure why the whole object could not be modeled as a T-Spline.

Modeling this manually should also not be too difficult, but I'd really need to know what the overall intention of the project is.

Re: Modeling complex/compound curves

Anonymous — Wed, 29 Apr 2020 18:32:58 GMT

I don't think the photogrammetry data is really going to help to be honest. My original intention for the dslr photogrammetry was... 1.) For fun, and 2.) I thought it may be possible to trace the trimesh and convert the traced line work to a body or possibly to use as a guide with the creation of a body. Tracing trimesh, which can be labor intensive, is sometimes used to repair or alter LandXML surface files.

I am certainly diving in and plowing through, but as a result I've learned a lot about the process. The tutorial you posted would have saved me much time scouring the web and piecing together the process. I was unaware that the faceted quad mesh would be smoothed out just by converting it. I did replay the section of you taking the mountain scene quad mesh and automagically converting it to an inert body and it seems all you did was click finish form?

I realize this cone should be relatively easy to build. It seems sculpting would be the way to build this but I have no idea how that works if you can't create limitations or molds/forms for a bit of guidance. The final product (especially around the cone) has tolerances. I will look into building the cone with cross sectional information while using a plane offset. The end goal would be to have the dimensional piece (not pictured) easy to alter after testing the piece, (wall thickness, length, additional support brackets etc.) so I am not sure having the entire model built as a t-spline would be the best fit?

I just have to say thanks for the guidance thus far. I have posted elsewhere, with only crickets as a response! 🙂

Re: Modeling complex/compound curves

TrippyLighting — Wed, 29 Apr 2020 20:06:47 GMT

I was going to use the scan data to be better able to judge how to actually model this. The photos only tell me so much 😉

There is a reason I asked you if you are familiar with the Sub-D modifier in Blender 😉

Just use the standard Cube Blender starts with go into edit mode and subdivide it once. The mesh will look just like a cube primitive in a Fusion 360 Form in Box view mode:

Now in Fuoisn 360 switch this to Smooth View mode. Either use the Utilities->Display Mode button or CTRL-1:

Your cube in F360 now looks all round and blobby:

That's more or less the same view you'll get when clicking Finish form, which converts the T-spline into a NURBS surface and/or BRep.

Now in Blender tab back into object mode and press CTRL-3. That applies a Catmull-Clark Subdivision Surface modifier to the selected object with 3 levels of subdivision. Right-click and select "Shade Smooth" from the menu and your cube in Blender now also looks all round and blobby:

That object is all smooth and has 24 faces without subdivision. That is the level of detail you need to export to Fusion 360.

Now I increase the subdivision level to 6. The object in the viewport still looks exactly the same.

Now it has 98,306 surfaces, but not carrying any more visually detectable detail than the 24 face object.

Yet, that is the object you exported 😉

If you would look at the resulting NURBS surface in another application able to show he NURBS control points, e.g. Autodesk Alias you'd see that is extremely densely packed requiring a lot of computational resources. There's no way to edit such an object in Fusion 360.

Re: Modeling complex/compound curves

Anonymous — Wed, 29 Apr 2020 23:54:58 GMT

You sir, are a bad ass.

I experimented and played around with the above work flow in Blender. Blender 2.8 is a bit different than what you posted but I worked through it. This is nice to know! Next week there will be an update for Blender 2.8.1.3 v3.5 and the menus will be changed again. 😉

Here is what I have! I'm going to experiment with getting these merged in a clean fashion.

Thanks again!

Re: Modeling complex/compound curves

TrippyLighting — Thu, 30 Apr 2020 00:02:03 GMT

@Anonymous wrote:

... Blender 2.8 is a bit different than what you posted but I worked through it....

This is the Blender version I worked with 😉

Re: Modeling complex/compound curves

Anonymous — Thu, 30 Apr 2020 00:31:49 GMT

Haha interesting. None of the shortcut combo's worked and the right click -> Shade Smooth doesn't exist in the menu. S'all good.