How to manipulate independently an edge in a T-Spline form without altering form

Anonymous · ‎01-06-2020

Hello Community,

I would like please to manipulate (extract, isolate, duplicate, or whatever else) a 3D edge loop in a T-spline form without moving or tweaking the form itself. The aim is to create a NEW solid using the isolated edge via extrusion.

The 3D loop edge that i want isolate is in fact delimiting a pattern to reproduce.

I'm working in the Form workspace and the T-spline form was obtained by converting a quad mesh.

I'm able to select the whole loop of edges but no more. I couldn't check the effect of the keyboard ALT button as advised by someone in the forum because nothing happen with that button pressed and edge being moved.

Please is there a simple way to duplicate and isolate the edge without redrawing it from scratch ?

Many thanks

TrippyLighting · ‎01-06-2020

Can you share your model ?

You could just copy/paste a face loop including that edge loop and work form there.

If you want to extrude an edge from a T-Spline, which is visible only in the T-Spline environment, but vanishes after conversion, then you can manually convert the T-Spline (Utilities->Convert), which will allow you to select the edges to keep.

Anonymous · ‎01-06-2020

Please find attached the model.

Hereunder a screenshot of the loop edge in question (in blue):

I'm still trying to apply your advices :

- Regarding the copy/paste of face loop, the selection is a bit complicated. Also i failed to achieve the copy/paste.

Nothing happen in the Form environment when copy/paste the slected faces.

- For your second advice it's ok. I was able to convert tspline to body and keep the desired edge. The problem is that slected edge is not necessary closed (not loop) after conversion. Maybe my model is not clean enough.

Retrying ...

Hope the attached model will give a clear idea of what i'm trying to do

thanks for help 🙏

Johnc911 · ‎01-06-2020

Unfortunately you can see from your screenshot that you no longer have an edge loop there. Did you add that feature with the ring around it? That is what is terminating your edge loop.

You will have to fix that if you want to restore an edge loop there.

Anonymous · ‎01-07-2020

Hi @Johnc911

Thanks for checking my post.

The model was purchased at CGTrader platform. It was initially a quad mesh I converted to T-spline thanks to Fusion 360.

In fact I provided the screenshot for purpose of illustration to show you what kind of edges I m trying to handle. You are right, the loop is broken in the screenshot but in my real use case I was able to select a full connected loop of edges by double clicking one small edge portion. The loop continuity was checked carefully .

I’m in fact trying to select the groove surrounding the skull eye to do something with (duplicate, extrude, create new solid based on that edge, )

If you have a moment please you can take a look to the model attached and check wether you can create new solid based on the groove mentioned above.

The model includes quad mesh + Tspline combined.

thank you

TrippyLighting · ‎01-07-2020

This mesh contains mostly quads, but there still are a relatively large number of triangles in it which makes it hard for Fusion 360 to deal with. Also with over 45k faces and considering the relatively large amount of triangles it's a pretty heavy mesh. One has to be careful when buying the meshes as they are created almost exclusively for further use in Sub-D modeling workflows where triangles are not such a problem.

You can select a face loop easily by clicking on one face and then hod the shift key and select the 2nd face loop in line with the first one. However, even in that eye area there are several triangles and poles (star points), which will result in pretty broken curvature of that face loop. You might want to consider fixing these first and then re-select that face loop, so you end up with better edges to build your model on.

Or as I do in the screencast, I fix the two areas of concern after copy-pasting the face loop, but before converting it to a surface. The effect is clearly visible.

While it can't be seen in the screencast, it took 2+ minutes after I clicked on the paste command for the dialogue to appear. I just cut that out. You might want to consider only importing the eye section so this is easier to wrk with. I would probably modify this mesh in Blender before taking it into Fusion 360.

Anonymous · ‎01-08-2020

Thank you for the demo @TrippyLighting and detailed infos.

Yes i noticed the heavy weight of the model. Over the few past days i tried to isolate a small parts of the model and convert them to T-Spline (using sliced STLs in Fusion and/or quad mesh in ReCap photo and handling it again in Fusion) but the final result is not accurate with some distorted areas and unclean edges, even with high resolution set in ReCap photo. I dont know why but this is outside the scope of discussion. I will try to use more appropriate tool

-- OK

I had doubt about poor perfs of my machine. You confirmed that when you said the copy-paste took more than 2 min. That's why i'm seeing nothing when copy-paste in my side for this use case. -- OK

Switching the solution to ACCEPTED.

Thanks a lot 🙏

TrippyLighting · ‎01-08-2020

@Anonymous wrote:

... using sliced STLs in Fusion and/or quad mesh in ReCap photo and handling it again in Fusion...

You never want to compromise you holy-grail-quad-mesh with such tools.

Triangulated meshes are the least common denominator for 3D geometry.

If you need help with isolating areas, I can help you with Blender. It takes minutes to to that in Blender.