Modeling smooth curved metal with holes

[Eric2575]

This has been giving me fits all night long. I can't get the surface smooth of this simple, yet compound shape - notice the deformations around the cutout. The cutout is giving me all the problems, but I have to have it there. Any suggestions on how to do this? None of the planes are flat and none are directly on the xyz plane. The piece is curved too.

 

The picture doesn't do the shape justice. The shape I am trying to get is very similar to the rounded quarterpanel of a roadster like the AC Cobra. Who is the expert on forming sheetmetal in AM?

[KenH]

It's hard to tell without the wireframe. Do you know about pressing shift when you connect a cp?

[starving4rtist]

A wireframe would be really helpful. I know it can be done though.

[R Reynolds]

It's difficult to tell from your image but I think you'll have more success if you build a rounded corner to define the edge of the cutout with a spline defining both sides of the corner (see attached image). There's only so much contour you can asked for in a 5 point patch. You may have to stitch in another spline to reduce it's area and hence the amount of contour.

[heyvern]

Depending on how the completed model will look you may want to try using a boolean cutter for the hole.

 

Create a shape for the hole, assign it to a bone and set the bone to be a boolean cutter. You may need to parent that bone to another bone or something like that to prevent other pieces of the model getting "cut". Can't remember the exact steps, I haven't used booleans in a while.

 

This would allow you to make a smooth shape with a perfectly cut hole.

 

Vernon "Hot air boolean" Zehr

[John Bigboote]

THIS may be a perfect time to use the AI Wizard. Simply create the shape you need in Photoshop with the bezier pen tool, when done choose File/Export shapes to Illustrator. In A:M make new model, right click in new window choose Wizards/AI

and specify the file you made in Photoshop, set the bevel options if desired and hit OK. A:M will do the modelling for you at that point, and it is usually quite good!

[heyvern]

Sorry Mr. Bigboote,

 

AI wizard only does flat shapes. He needs one that is curved on both the y and x axes.

 

On that same note, Eric2575, you may want to try using the distortion thingy after using the AI wizard to bend the shape. Or use distortion on a flat shape you created. You will need extra splinage in there, "cross wise" if you follow.

 

I find the distortion thingy does a pretty good job at keeping the shape of stuff. I haven't used it for something this subtle before.

 

Keep us informed!

 

Vernon "!" Zehr

[Eric2575]

Thanks for all the input. Ken, I know about the shift key. The problem is the slight adjustment after laying down the splines. Since the piece isn't on any axis, any movement of a cp, even if ever so slight will deform the dang thing. I can't model it on an axis and rotate it later because it is curved in two directions.

 

The attached pic shows two attempts (out of many), one on each corner of trying to get a smooth surface at the corners.

 

I will try all of your suggestions and keep you posted.

 

Thank you

[hypnomike]

Do you know about pressing shift when you connect a cp?

 

Ken, I know about the shift key.

 

What about the shift key guys???

 

I move over the point and right click, is there something I should know?

[robcat2075]

Your treatment of the curved corners has several awkward spline intersections.

 

Here's a take on your shape created with the mesh flat first, the using a 3x3x3 distortion box to bend it on X and Y. It still has a few lumps in it but Porcelain.mat would make it very smooth.

 

A Vern noted above, the splinage should be very regular for good distortion box results. Mine should have been more regular.

[KenH]

What about the shift key guys???

 

It's mainly for stitching a spline into an existing mesh. Pressing the shift key as you make it causes the new spline to align and integrate perfectly into the existing model.

[hypnomike]

Hey thanks for that Ken, you may just have solved some anomolies I came across in my giraffe model!

[starving4rtist]

I just quickly threw this together to show you what I would do. Anyone else, feel free to prove me wrong

[Eric2575]

Here is my latest attempt with everyone's help. Although it is very smooth, I can't brag because I still need to bend it. I'm gonna try distortion - have to find a tutorial on how to do that.

 

Will keep ya posted.

[robcat2075]

I know how to get into distort mode but am unable to do anything in it.  ...  You mentioned a 3x3x3 distort box? 

 

You can set the number of divisions for distort boxes in the Options>modeling tab. The number of divisions you choose will depend on when you need to distort your model.

 

Once you go into distort box mode it puts what looks like a box of splines around whatever you had "selected".

 

You can drag the CPs of that box around individually or select and group them or use any other tool just like CPs in a model. As you distort the proportions of the box the original modle mesh enclosed by the box will follow that distortion.

 

Q:Why is this different from moving the original model's CPs?

 

A:The box has far fewer CPs than your model so it is easier to make broad curves over a complex mesh than if you had to adjust the complex mesh directly.

 

While distort boxes do a good job of moving the CPS they aren't smart enough to adjust the biases between distant CPS to match the new broad curvatures. That's why distort works best on meshes with fairly regular splinage.

[Eric2575]

Rob:

 

Thanks for the brief, yet very concise explanation of the distort. I played around with it and in a few seconds had the shape to where I wanted it (will tweak it a bit later.) The ability to change the xyz box factors is great - AM rocks, this forum rocks, you rock

 

Here is a question before I started distorting the mesh - before. The mesh was already pretty smooth, so I wanted to see what porcelain would do. See the attached pic. What is causing the unwanted distortion, and what can be done about it besides removing the porcelain?

 

The distortion is not there without the porcelain.

[John Bigboote]

Make sure your normals are all facing the same direction. Porceline needs that.

 

Yes, the distortion box feature is very powerful and straightforward and easy to use. Do not be intimidated, it's a piece of cake. Works good in actions and poses too! Play with it for 1/2 hr. you'll know all there is to know.

[Eric2575]

I want to thank everybody for the great input and being patient in teaching me. This has been a very good experience. I'll post the final piece when I'm done with it.

[filipmun]

Hey, here is my version of faking the geometry with decal.

 

The fact that I usually don't have the time to do everything in AM and mechanical modeling is quite difficult, so I come up with this technique.

 

No tricks, just use a transperency decal to cut a hole and place the necessary parts in place.

[filipmun]

Here is the sample prj

Fake_geo.zip

[robcat2075]

No tricks, just use a transperency decal to cut a hole and place the necessary parts in place.

 

No, I think feathering the transparency is a brilliant trick! That does alot to make the backing geometry appear to match the cutout. Hard edge cutouts always look weird.

 

Will remember that one! thanks!

[Eric2575]

I like it too filipmun.

 

Here is my final piece. I haven't dealt with lighting yet, so the rendering doesn't do the shape justice. It is warped on all axis, has the shape I need and looks very smooth. This is part of the Nautilus (Disney) that I am modeling as my first project.

 

Again, thanks to all of you for your guidance.

[Biotron2000]

Great subject. I'm looking forward to seeing more of it!