3D spline on Mesh

[Anonymous]

Hi Everyone

I did not find a solution in order to snap a spline onto a 3d scan data?

Is there any trick or work around?

Many thanks in advance

[paul.clauss]

Hi @Anonymous

To snap sketch points (including spline control points) to a mesh body, you will need to convert the mesh body to a Brep body. I have illustrated this in the screencast below:

Please let me know if you have any questions - I'm happy to help!

[jeff_strater]

Hi @Anonymous,

The short answer is "no", you cannot snap a spline to a mesh body.  A mesh body today is really somewhat limited in its functionality in Fusion, especially in using them for operations in the Model and Patch workspaces.

What is your goal here?  What are you trying to do that snapping a spline to the mesh would help you?

There are some techniques that can help, depending on the answer to the question about your goal.

• If the Mesh is less than 10,000 faces, you can convert it to a BRep body, and then snap the spline to the BRep.  This works, but I don't recommend it - the resulting BRep body is very heavy, and does not respond well to other operations
• You can use "Snap to Object" in a Sculpt feature to create a body that conforms to the mesh, and use that result to snap your spline to

I'd be happy to provide more info on either of these options

Jeff

[Anonymous]

Many thanks but unfortunately I can't use the conversion tool; the original scan data contains around 3.5 millions of polygons. I already reduced the  data in Geomagic Design x

Again, I have done the decimation within Fusion one more time in order to get a "super light" STL but seems I have to insist

(I need to preserve the polygons density around the intersection areas).

[Anonymous]

Thank you Jeff.

I'm interested in getting Class-B surfaces from scan data by using Fusion.

Firstly, I tried to use the freeform workspace but, frankly speaking, is not quite easy generating a decent t-spline layout.  In terms of deviation, I have to stay around 1 mm from the scan data (0.5mm would be better). Secondly, I was playing within the patch workspace but just right now I have realized that is not allowed setting the tangency by using 4 edges (loft tool). Seems I have to give up.

[jeff_strater]

Hi @Anonymous,

Thanks for the info.  If what you are after is what I would call "reverse engineering" from the mesh, there are a couple of approaches that might help.

First, as you've already found, there is the TSpline approach.  As you've discovered, that method is not great if what you want is to rebuild the whole mesh as a TSpline.  It can be useful if what you want to do is just map out a part of the mesh to use as a reference.  The example that always comes to mind here is using a scan of the inside of a car's engine compartment to make, for example, a windshield washer fluid reservoir that fits up against the surfaces.  Then, you would just use Create Face with "object snap" to get just the part of the surface that you need.

Another method is to use the Mesh Section and Fit Curves to Section commands in the Fusion mesh workspace to create sketches that can be used to rebuild the part using features in the Model workspace.  Here is a rather long-ish screencast of doing this on an imported mesh.  This is a much different model than yours, so you would use different features to build it, but the basic technique is useful, IMO.

Finally, there is another Autodesk product: Autodesk Remake that is intended for dealing with large meshes.  I'm not an expert on this product, but I think you can use it to "quadrify" a mesh, meaning to produce a mesh with 4-sided facets.  The advantage of this is a quad mesh can be imported into Fusion and automatically converted into a TSpline.

Hope one of these works for you...

Jeff

[timUTXF2]

It is now 2019. I cannot put a spline point on the nearest intersecting Mesh Vertex Point. And Fusion runs like my fat self in a Marathon if I even reduce an STL to 40000 faces and then do a BREP conversion, just for the purpose of finding points to reference, it's overkill.
Whatever code is used in (Autodesk) Meshmixer to drop a pivot point... could it be that hard to mimic that in "Drop Point to Surface/Vertex"?
Marking important points in 3D space of a mesh then auto-creating a Spline doesn't sound like Black Magic.
Autodesk has at least 712 different 3D products, why? This seems like a very basic, needed design tool.

[TrippyLighting]

A mesh in Meshmixer is really still a mesh. A mesh converted into a BRep is a BRep. Even in 2019 😉

All mesh facets are converted to mathematically analytical surfaces, which is much heavier in data and also more computationally intensive.

Fusion 360 is not the right tool if creating a spline from an imported 3D mesh is what you are looking for. One of the other 712 AD products might serve that purpose better. Try Autodesk Alias.

[timUTXF2]

Thank you for the suggestion on the product.

And thank you for the time you take to answer so many post on here that I read and learn from, but never comment. Your contribution to our education and productivity cannot be measured. Thank you!

I am trying a demo of Geomagic Free Form. I had previously tried a demo of Design X and it was confusing.
Free Form is much more intuitive than I expected.
My gripe with Fusion is that I can see the mesh, so I know all of the edges and vertices are right in front of me. I should be able to snap to those points. Give me a checkbox while 3d sketching "snap to mesh coordinates."
Cinema 4D has a spline that will project into a mesh...
Even the ability to just drop points on a mesh surface as meshmixer does would be amazing... Just add them as a construction item, even. Then I can choose them when making a 3D spline sketch.

While I am on my wish list, let me pick multiple segmented flat surfaces then click a box that says "pull flat to a plane" and show me the variance from axes and the deviation.
Then if we are really being crazy, let me click some boundaries on a rounded/organic section and a few surface points then select a button that says "Generate surface to this area."
Between loft, patch using points and edges inside of patch, and t-splines pulling to surfaces, everything needed is already inside a Fusion, certainly.
Again, Sir, you are much appreciated!

Tim

[TrippyLighting]

That sort of reverse-engineering functionality exist to some degree in other software packages, namely Spaceclaim.

But then that comes a a cost!

[mah56]

Oh wow i wondered the same things since i use Fusion360, and i discovered Autodesk Atlas with this topic...

Well, like you i'm thinking that everything is included in F360 to have better tools like sketch snapping on mesh (without brep), better mesh section tools etc. But now that i know Autodesk Atlas exists, i think it's dead : they'll surely never implement simple but essential tools to F360 as it is free for small company or 60€/month, while Atlas costs 10 times more.

They keep the most useful tools on the more expensive software, that's all. Understandable but sad.

[TrippyLighting]

I am assuming that you are talking about Autodesk Alias, not Atlas ?

Alias is a high end surfacing software surely aimed at high end vehicle surfaces.

Technically Fusions 360 is not able to do this.

[mah56]

Oops yes, even with a mispell i found an autodesk product... They have one for every thing apparently.

However, what makes you say that f360 is technically unable to do that ? Since 3d sketching is possible by moving manually points of the spline, and as each vertexes of a mesh has coordinates... I wonder why it is impossible to give this sketch point the same coordinates.
In form mode, you can draw a surface with object snapping directly on mesh, if a vertex of a surface can snap on the mesh, why not a 3d sketch point ?

If you have technical explanation, i would be happy to understand more why it's impossible as it interests me.

Edit : also "mesh section" is a tool that draw a sketch based on a mesh, isnt it ? I mean, it draws the sketch in real time while you are moving the plane, it seems technically possible. I still think that enhance the tool by letting user drawing like they want (plane section are sometimes not suitable for some projects) is like bringing some alias possibilities, and there's no logic for them to do that as they want user to pay for alias, not for f360.

[TrippyLighting]

I was not referring specifically to snapping spline points to a mesh. You were comparing Autodesk Alias abilities with Fusion 360 abilities and then continued to elaborate that "they" keep some tools in their more expensive software.

Alias plays in a technical league of surface generation tools that Fusion 360 cannot attain as the underlying geometric modeling kernel in Fusion 360 does not have the technical ability (higher order surfaces) to implement such tools.

Even if you can snap spline points to a mesh that will not allow you to properly reverse engineer a surface from a scanned source. If you want to re-create a curved surface based on a scan or otherwise triangulated mesh for use in Fusion 360 I'd look at re-topology tools outside of Fusion 360 and Autodesk. These create quad meshes that can perfectly fine be used as T-Splines in Fusion 360.

[mah56]

And i was referring about enhancements on sketch snapping and mesh section that F360 already does well, for using them as a base (principally to create stuff based on the scanned object, not doing reverse engineering of the object), not surface creation / editing like Alias does, that's why i still think there is no "technical problem" to enhance these simple tools.