Can not convert mesh to parametric solid

[Anonymous]

Hi there,

I am using Fusion 360 to convert segmented surface mesh to parametric solid body, but it does not work well.

This is how i worked with the model:

open file > reduce to 10000 faces > generate face groups > combine all the face groups as one > convert mesh.

The model works when the conditions are set to 'Faceted', but I want it to be 'prismatic'.

When I apply 'parametric' setting, the error message shows as below:

The model needs to be imported to CAD program, so as to use it in simulation software.

The model with 'Faceted' option is counted as 5000 faces when imported in simulation program, also it has some unstable faces. 

Would it be able to convert to prismatic solid?

Will models with prismatic option solve import problem in CAD-based simulation program?

Thanks in advance. My models(original model and reduced one) are attached below.

[HughesTooling]

Prismatic will not work with organic shapes. Prismatic can only convert to boxes, cylinder type shapes not monkey type shapes 😉

See help here.

https://help.autodesk.com/view/fusion360/ENU/?guid=MESH-OVERVIEW

Edit

@TrippyLighting Has a post on converting organic shapes somewhere. 

Mark

[TrippyLighting]

I made the video below more 2 than years ago. Before you attempt to follow that workflow, you should consider c leaning up the fringed edges of the scanned .stl and trim off what you don't need. Then you'll have to experiment with the settings in InstantMeshes a bit to get to the desired result.

https://youtu.be/aMZKgzBpodI

[Anonymous]

Thanks for your reply.  I've tried the method you posted on Youtube(head sculpture one), but I got a problem with it.

After I converted my mesh to form, error message show up: 

So I used auto repair from modify menu: figure below is after going through auto repair once.

It looks fine to me since there's no red star marked around it but same error message shows again when I click on 'Finish Form' button.

I also tried to repair mesh to remove the warning sign beside the mesh icon: it says 'Mesh is not oriented. Mesh does not have positive volume.'

After repairing, the mesh is not selected as mesh body when trying to convert quad mesh to t-spline in 'form' menu.

Is there any way to solve this? Thanks in advance.

[Anonymous]

Thanks for your reply, Mark.
However, I got a new problem dealing with the model(what i posted above).
If you have any ideas, please leave me a reply.

[TrippyLighting]

Can you post the .obj created by InstantMeshes ?

Zip the file before attaching it to a post.

You might want to try a much lower mesh resolution . There is no need for that many quads!

[Anonymous]

Thanks a lot. Here's my file.

As you told me, I'll try reducing meshes! 

[Anonymous]

While I was working with my model with 'InstantMeshes', I found out something strange(black region):

Would it be the reason why quad mesh could not be converted to t-spline?

How can it be solved,,? Is it a problem of the model itself??? 

or is it just graphics,,,,,,,,,,? (actually i want it to be just graphics,, )

Thanks in advance, ^0^ !

[TrippyLighting]

Before we continue, please explain what kind of simulation you want to perform on the object.

I also mentioned in a previous post that the mesh needs to be cleaned up and perhaps smoothed in some areas.

That is likely better done to the mesh before remeshing in InstantMeshes.

In teh video I use Blnder and Meshmixer. If you work more often with this sort of geometry then Meshmixer is an indispensable tool.

[Anonymous]

I'm going to use this model for simulation for ultrasound propagation through skull. 'COMSOL Multiphysics' software will be used. I rarely touched the model since skull thickness data is the most important part, which should be preserved.
Wouldn't editing the mesh with 'Meshmixer' harm the original mesh? I'm just worried.
I already went through overall surface smoothing with 'MeshLab' software, using Laplacian and Taubin smoothing.

[hfcandrew]

And what file type does you final model need to be in. Is a triangulated mesh okay? Is so then why are you even trying to convert to a solid?

Also, are you sure your model is scaled correctly?. Its like 700mm (27 inches). Also when I loaded it into MM, its zero point was 9000mm (345inches) off from the origin.

Your model is watertight (solid) after fixing 3 problem triangles with Analysis>Inspector in MM. No conversion, no 'reducing' triangle counts.

Sorry to say Fusion360 sucks with high density organic meshes. If you have a mesh, use Meshmixer (despite it sadly being recently abandoned by autodesk...)

[TrippyLighting]

---

@hfcandrew wrote:

...n why are you even trying to convert to a solid?

---

I am not sure that is the case with the simulation software the OP wants to use. I assume it is, based on his last post.

Much of simulation software today is FEM based and that requires BRep geometry. Usually the simpler, the better. As such , in order to reduce simulation time and memory, the model will be simplified. Fusion 360, for example has built-in functionality do to this with mechanical models.

THe Brep is needed as it has a clear inside and outside. That is needed for the software to create a usually tetrahedral, volumetric mesh, which then forms the basis of the analysis.

[Anonymous]

1. I want it to be .step file since I want to use 'PZFlex' software in my lab, which i prefer to use.

This program needs .step file to input.

However, since Onscale stopped updating the software since 2018, i'm not sure the model can be imported properly in the program. I've already tried to import .step file that I converted from the mesh(reduced one) using Mesh>Convert Mesh from Fusion 360 but it failed, so I was trying to make more stable model with fusion360. Triangulated mesh would be fine.

Actually I didn't get to use such simulation programs like Ansys or COMSOL, so I don't know how it goes on, does the software itself convert surface mesh(.stl or .obj format) to solid? My model needs to be solid; it needs to be work like a solid skull through simulation. Also, is it possible to repair meshes inside the program? 

2. I don't get why the scales went wrong,, When I first generated model from segmentation from CT scans, the scaling was fine, height is 70mm in reality. But starting point was also weird at that time, too. I'll take another look at the model. Does scaling factor changes if I change any settings from Fusion360? 

3. Is meshmixer good for dealing with organic models? I found it quite tricky to use,,, 

Anyway, thanks for your reply 🙂

[Anonymous]

I do get your point, simpler model is needed for speed and Fusion 360 is a great tool to make it.
I already got Brep file by converting mesh to solid in faceted option, but I just wanted to make somewhat more stable model for the reason of PZFlex import problem(described above).
I thought mesh > T-spline > Brep would yield more stable model, but i guess it cannot be applied to my situation,, I guess I should deal with mesh problems first as you told me.

Would Meshmixer be the best tool for dealing with meshes? I don't see any intuitive way to solve my problem in Meshmixer. Please notify me if you have any suggestions. Thanks a lot. :0

[Anonymous]

omg it was analysis, not ansys,,,,,,,
sorry for the confusion! I'll try that with meshmixer!

[TrippyLighting]

I compared the original .stl mesh and the quad mesh created by InstatMeshes.

There are less than a hand full of small areas predominantly around the holes that I would "fix" using meshmixer.

Then, after remeshing in instant meshes I might again inspect the resulting geometry and perhaps fix potential problem areas Using Blender, or even Fusion 360.

Modifications on these small problem areas are unlikely to have an effect on your analysis. If I have time this weekend I might demonstrate how to do this.

In general, working with scanned geometry with general-purpose tools rarely is a on-click solution.

[hfcandrew]

No worries.

Of all the Mesh editing and/or mesh repair software out there, Meshmixer is often described as the simplest.

[hfcandrew]

No worries.

Of all the Mesh editing and/or mesh repair software out there, Meshmixer is often described as the simplest.

Like anything, just needs a little reading: https://help.autodesk.com/view/MSHMXR/2019/ENU/

[Anonymous]

What do you mean by fixing the meshes?

Fixing the original mesh or quad mesh by InstantMeshes?

[Anonymous]

thanks a lot 🙂