Turning a closed sketch into a face

[Anonymous]

Hi Everyone,
I have drawn a closed sketch of a shape I want to turn into a editable t-spline. Is there a way I can turn this sketch into perhaps a face that means I can subdivide into muliple faces to modify in sculpt mode?

Thanks for your help

[jakefowler]

Hi Simon,

Thanks for your post, and welcome to the forums!

Creating a T-Splines surface that closely matches an input sketch is unfortunately not quite as easy as it might seem (as you may have discovered!). There’s a few ways you can do this, and the method that’s most suitable probably depends on the shape of the profile you are trying to match, and what you eventually want to do with the surface.

The most common way would be to use the Face tool to build up a set of T-Splines faces that approximately match the input profile. If you want a closer fit, you could follow this with the Match tool to match the outside T-Splines edges to the profile curves (note that this could end up subdividing your faces further - increasing the tolerance might help if this happens). If use this method, sharp points will remain sharp (but these may become smooth if you work with the surface downstream, such as using Extrude).

The below video shows this workflow:

 http://screencast.com/t/KRofMJkqvjD

Another method I sometimes use, which might work well if you your sketch profile is smooth all the way around, is using the Extrude tool:

1. Start the Extrude tool, click your profile, and extrude it away from the sketch plane (modify the face number & distribution until you get a good match to the profile - an even number of faces is recommended). 
2. Open the Edit Form tool, select the edge loop that follows your sketch profile (double-clicking one of the edges will select the whole edge loop), and Extrude this inwards by holding the Alt key, and dragging the scale manipulator inwards. Your surface will start to curve away from your sketch, but don't worry for now...
3. Delete the set of faces that you created with the first Extrude (you can do this by window selecting these faces, and pressing the Delete key). You should now have a flat ring of faces that travel neatly around your sketch profile. 
4. You can then use the Fill Hole tool to fill the hole in the middle. If the Reduced Star setting doesn’t give you a nice edge layout, change the option to Fill Star (which just gives you one big face), and use the Insert Point tool to split the big face into a patchwork of four-sided faces (you don't have to do this, but it's strongly recommended if you’re going to continue working with the geometry).

Video of this workflow here:

http://screencast.com/t/2rmi4y7RmI

If you’re able to share the sketch in question (via f3d file, or just an image), and if you have any more details on what you want to do with the geometry, we can probably give some more specific recommendations on how to create a good surface for it.

Hope this helps!

Jake

[Anonymous]

Thanks heaps Jake for that awesome reply!. I thought this might be the case. The second option is probably more appropriate for may shape as it is all splines.
I am currently working on a project around face masks for dust etc and we are trialing the 360 software. 

Im not entirely sure if Im going the right way about this but this is my plan of how to make a facemask shape with the small fusion experience I have. The sketch I am working off ( no dimensions yet) I have uploaded. I'm also unsure whether I should model this as a solid mask first and then hollow it out (How I would do this Im not sure, perhaps shell it then delete the back face off the solid body to make it a hollow mask). Or should I create it just through flat faces then thicken them once I have the final shape.

The Plan

Create a base sketch shape of the mask outline. Turn the sketch into a face. The wrap or push this face over a curvaceous head like surface. The sculpt our the shape of the mask from the now curved face.

I hope this makes sense. I've seen the other recent thread on masks but Im still at quite a fundamental stage and am not sure which tools would be best to use to create the shape or how to take the ketch into a face mask. Any advice on this process and mask design would be greatley appreciated!

Edit: Forum wont seem to let me attach my .f3d file when attaching it just says "The contents of this attachment does not match its file type"

[jakefowler]

No problem, glad that helped!

Sorry you’re having problems uploading the file - I know we had a problem like this before, but it should be working now (perhaps this is related to the browser being used?). Anyway, you could try zipping it to a ZIP file, and attaching it like this. Or, you can email it to me directly at jake (dot) fowler (at) autodesk (dot) com.

The workflow you describes sounds reasonable to me - T-Splines should be perfect for this kind of job. Assuming your mask is going to be thin, I would recommend starting by working with a flat surface, and then only thickening/shelling when you have to: this will make modelling the overall shape a lot simpler. You may also need to convert the T-Splines model to a solid model if you want to add small details (such as holes, attachments, etc.). Again, it’s best to do this only after you’ve finished making the overall shape of the mask.

Hopefully you found this other recent thread about mask design; but if not, Paul posted a download link for a headform T-Splines model, which you could use as a reference for your model.

If you’re able to send us the sketch curve, and/or you can send (or link to) an image of the kind of thing you are trying to create, I’ll try to offer some workflow tips on how I would approach it.

Thanks!

Jake

[Anonymous]

Thanks again Jake for your help. I have emailed you two files to try and show you what I am doing. I tried to upload again on a range of internet clients but no luck. The mask I am designing has to be quite accurate in terms of facial dimensions and how it will fit on to the face. The sketch ulpoaded shows the linear dimensions I need. One way of tackling the problem I think could be to turn this sketch into a number of faces ( however you think would be the best way to do that), and then push this shape onto the curved surface/head to get the curvature needed around the cheek areas etc. Then from this we sculpt out volume.

The second file I have uploaded is the ideal kind of shape I am looking to get in the mask. I made this just from deleting half a quadball and then sculpting out. The reason im not just using this is thats its not dimensionally accurate at all and does not have the correct curvature needed to fit onto a head. 

I  suppose my real question is then how would I create that mask shape the most dimensionally accurate and easiest way? I can dimension sketches but I dont know how I can dimension an existing t-spline surface and put in a circumference into the curvature of the mask. Would it infact be easier just to start with a primative tspline surface like I did but apply dimensions somehow? I hope this is not too confusing for you and thanks again for your help!

[Oceanconcepts]

I'd just like to flag this as exactly the sort of issue it would be good to go over in the Fusion Hangout. We discussed using the Hangout to work out and illustrate strategies for solving real world problems. 

Integrating T-Splines with the need for precision (since F360 allows you to do both in the same space) demands some workflows that are unique, and requires some creative thinking.

[jakefowler]

Hi Simon,

Many apologies for the delayed reply, it took me some time to sit down properly with this; hope this hasn’t caused you too much inconvenience!

I think both workflows you mention are valid, and either could give you the result you need.

• The advantage of starting with a primitive (e.g. a quad ball) is that you automatically get a closed shape with a nice, well-distributed set of T-Splines faces: the tricky part, though, would be moulding this to your required specifications. 
• Using the Extrude, Revolve, etc. tools gives you more control over the initial form, but it will then take some work to close the model cleanly, and getting a nicely-distributed set of T-Splines faces is more tricky.

Unfortunately you can't currently 'apply' dimensions to a T-Splines body, but the Match tool allows you to approximately match a set of T-Splines edges to some existing sketch (or BRep) edges. Have you tried this approach? I'd recommend doing this by deleting one half of your quadball model, using the Match tool to match the bottom edge to one half of your sketch profile. Enabling 'Refinement' will allow you to specify a precise matching tolerance, but will probably need to add extra edges to do so, which may not be desirable.

After this, use 'Mirror - Duplicate' Symmetry to generate the other half again. Perhaps this workflow works for you?

Alternatively, below I've detailed another workflow which seemed to give me a decent result, which was a 'hybrid' approach: use part of a quad ball to sculpt the required 3D form, then extrude a set of faces that matches your input curves, and weld the two shapes together.

1. As you did in the file you sent me, mould a quad ball (or other primitive) into the shape you need, not focussing too much on matching the outer edge to your precise curve.

 

Then delete the outer ring of faces of this shape: we’re going to replace these with an extruded set of faces.

2. Before extruding the curves, an issue I hit on the file you sent me was that the two halves of the curve loop are not neatly smooth with each other: this means you end up with a crease at the top & bottom when you extrude the curves. This is generally easily fixable - you can use the Uncrease Edges tool to remove the creases in the extruded surface - but uncreasing will change the shape of the surface, no longer giving a good match for your curves. So, it’s best to get the two halves of the sketch smooth with each other first.

Edit the sketch, and open the Constraints panel: the tangent handles for the sketch splines should appear.

Select the Horizontal constraint tool, and click the tangent handle for the top point: this should make the tangent direction horizontal for both halves, giving a smooth connection where they meet.

Do the same for the bottom point. 

The curves should now be tangent continuous all the way around, giving an uncreased result when extruding.

3. Now extrude the sketch loop. The best workflow would be to use the same number of faces as you have edges around the outside of existing moulded shape (for a 4x4 quad ball, this will probably be 16). But it’s possible this won’t give you a satisfactory match to the sketch (although sometimes some manual adjustment of the shape after extruding can give you a better fit). Or, you could use a larger number of faces (although try to keep this number as low as possible). 20 gave me a pretty precise match.

4. If you used a larger number of faces in step 3, you will need to increase the number of edges on the outer ring of the moulded surface, so that we can weld correctly. You can use the Insert Point tool to ‘split’ some of the outer edges of the moulded body in suitable positions. Or, use Insert Edge/Subdivide to add extra edges around the outer loop. Note that doing this will likely cause slight changes to the shape of your moulded body.

5. Once the two edge loops have the same number of edges, start the Weld Vertices command, and sequentially weld points from the extruded surface to the moulded surface. The model will become 'boxy' while you do this, but should resolve to a smooth model once you've got round the entire loop. (Before you do this, I would recommend removing symmetry from both bodies using the Clear Symmetry tool - there’s an issue at the moment with connecting symmetrical bodies, which we’ll try to resolve in an upcoming update.)

The result should be a moulded shape that nicely matches your curves.

(If you added edges with Insert Edge/Subdivide in step 4, you may be able to delete some of these (click them and press the Delete key) without any significant change to the moulded shape. The advantage of doing this is that it might make subsequent moulding a bit easier.)

Perhaps this will work for you? If not, hopefully it still gives you some ideas about how you might be able tackle this.

If any of this isn’t clear, or if you're still not having any luck, please do let us know.

And thanks for the point about our hangouts, Ron, I’ll let Mike know about this 🙂

Best regards,

Jake

[Anonymous]

Hi Jake,

Thanks for that awesome reply, and the time you put into making it. I was able to create the mask I was trying to make with the closing frace method you mentioned before along with wrapping it around a spherical shape. I then went in and sculpted it out. I also went through your way and was also able to get a good result. The tip on the sketching aswell was great to know. I've been progressing alot with fusion and trying out as many tools as possible and It is going great so far. Thank again for your help Jake.

Simon

[dunderhead]

Jake -- thanks for great videos. I have two questions about method  #2, which I tried out.

Question 1. As you can see the t-spline extruded from the profile matches poorly to start with (whether you choose 'uniform' or 'curvature').  Adding many more faces helps little, so the algorithm used for this operation appears to give a pretty poor result in this case. Is that a bug? [Doing a 'match' on the loop of the edge afterwards is the cure, but that adds ghost vertices which are rather confusing (at least until one start to understand them!).]

Question 2. The second extrusion doesn't work in some cases: you see it below where the yellow edge has grown the wrong way, according to flipped normals in the tight middle bend, around the position of the navigator!! I would think that the is a bug??? If not I'd suggest a feature for scaling with normals pointing in the same topological direction!

-dh

[jakefowler]

Hi dunderhead,

Apologies for the delay in getting back about this one.

Regarding question 1: We default to just 8 faces, which tends to be a good default for simpler profiles but sometimes isn't enough to get an accurate representation of more complex shapes. So the recommendation here is indeed to increase the number of faces until a satisfactory match is achieved. Using Match is another way to do this, but as you've seen this will often insert new points automatically to achieve the match. A third option, which requires a bit more work, could be to extrude this profile in the Patch workspace, then switch to the Sculpt workspace and use the Convert tool (switching to the BRep selection filter) to convert the patch surface into a T-Splines surface. Using the Curvature option in this command will actually allow you to specify the surface fit tolerance, and choose the number of faces automatically. If you try this out, would be good to know if this works better for you. 

This does raise the question of whether a similar method for curve fitting may be possible in the Extrude command... I'll look into that.

Regarding question 2: extrusions done in this way will always be with respect to the centre of the manipulator, so unfortunately this is the expected behaviour for now. But normal direction extrusion could well be useful in situations like this. I'll discuss with the team here and see what the feasibility of that is.

However... that has given me an idea for an improvement on the workflow I originally suggested:

1. Extrude the profile normal the sketch plane (as in the previous step 1).

2. Thicken this surface inwards, leaving the default options (i.e. leave thicken direction as Normal)

3. This builds a 'solid' made up of the original surface, its offset, and two sets of 'side walls'. These side walls should actually be giving you the faces you're after, so select the rest of the model and delete it to leave you with the required faces.

Video here: http://autode.sk/1waMiqD

Does this help for the model you are trying to create? If not, let us know!

Many thanks,

Jake

[NickBecker]

Hi guys.

I have been following this thread in detail and I understand the concepts being explained. I would like to know if you have for instance a closed sketch of a pair of eyewear frames, how would one go about closing the sketch up with t-splines to create faces more accurately than physically drawing the t-splines and using the mask function. 

I found drawing the t-splines takes allot of editing and even then my curvatures are rarely matching the sketch curvatures... 

I'll attach my sketch, any help would be greatly appreciated 

Thank you in advance.

[Anonymous]

I don't know if I understand the question right, but you can sketch it first, then select patch workspace->Create patch-> then you get a surface! If that's what you want!

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