How to join cylinders?

Tom Ellis

Hey there,

I'm having some modeling issues trying to join two cylinders together.

I just want to connect the two cylinders where they intersect and have a smooth transition between the two. Kinda like how a bike frame is welded together.

I've looked at both Sathe's method, and Ben Tate's which is simlar, but the problem (unless I'm missing something) is that it only works when the adjoining cylinder is of a certain size in comparison to the other cylinder.

In this case, I need the cylinders to be a specific size... .13 units and .16 units.

Using the method in Sathe's tut isn't working because the cuts are too close to the existing edges which results in pinching when TS'd.

Of course, it may be possible to adapt the method to make it work but I'm having trouble.

I know a simple alternative would be to just shove the cylinder into the other and use mentalRays hard edge bevelling thing but I feel I should really know how to model it properly.

I get the impression this is one of those situations where there is a way of doing it that can apply to any size cylinders... I just don't know that way of doing it!

Here's a screenshot explaining it... if you wanna try it, I'm using a 12 sided cylinder of .16 units radius, and an 8 sided at .13 units... only the size difference is important, if I need to up the number of sides then that's no problem.

whipSwitch

why not add more sides to the larger cylinder?

Tom Ellis

whipSwitch wrote: »

why not add more sides to the larger cylinder?

When I try this I get flatspots around the joint when it's TurboSmoothed.

EDIT: This might well work, I'm probably doing it wrong.

Tom Ellis

OK sorted, the Ben Tate method worked.

And as you said whipSwitch, adding more sides to the cylinder was the solution.

Thanks!

Tom Ellis

These cylinders are still causing problems!

I'm modelling a bike frame, and it's taking me such a long time that I'm rethinking how to go about it.

The difficult areas are where the back section that holds the rear wheel join the frame under the saddle, and also the bit where the pedals go where you have like 3 bars joining at the same point.



Is it even worth modelling them so they actually join? Or would it be better to just edge them up to each other, and maybe add some weld detail with ZBrush or even just the sculpt geometry tool?

In reality, the tubes are obviously not inset into each other, they just butt up and are welded.

Part of me is thinking I should learn to do it since it'll improve my skills, but part of me is thinking I could save a lot of time and finish with an equally good if not better result by not actually joining the cylinders.

What would you do?

There is gonna be a low poly eventually so I'm keeping that in mind, but I'm thinking I can just use separate cylinders for each bar, and just flare out the end to encompass the weld.

Eric Chadwick

These examples might help.
http://www.etereaestudios.com/training_img/subd_tips/agujeros.htm
(English translation from Google)

monster

I don't think it's that important to join them. Imagine the asset in game, will the player ever walk up to the bike frame and inspect it?

Tom Ellis

Thanks Eric, those'll certainly be useful, not just for this project, thanks.

Monster -

That's kinda what I was thinking, either way is gonna yield equal results I think and if anything, the non-joined method would be more realistic.

I think it's just me being overcritical thinking I should be able to do it... I probably should really, but I'm just gonna save so much time doing it the other way and less frustration for hopefully a decent result.

Thanks again.

Tom Ellis

Just found this... pretty much answers all my questions!

http://www.staticcurve.com/Artists/viewtopic.php?f=11&t=168

Thanks a lot Bitmap if you read this!

I_R_Hopo

Okay, did this quickly to show how I'd go about it. Technically there is some slight warping on a few faces, but nothing noticable. Sorry for the crappy image too :P Hope it helps!

Tom Ellis

Thanks man, that's very similar to the method I've been using. Problem is, it gets very tricky and almost impossible to implement that method in some areas, notable on the crank (not sure if that's what it's called) bit where you got like 4 cylinders intersecting at different angles.

I'm just gonna butt them up against each other and sculpt welds, it'll look better, be easier, take less time and really it'll replicate how they're built in reality... *insert more justified reasons for cop-out here*

Eric Chadwick

It's not a cop-out if the asset works well in-game. There are all kinds of cheats we do to get something done in time. monster has it right, it's the result that matters.

Pedro Amorim

oh
i'm everywhere lol

Slum

EricChadwick wrote: »

It's not a cop-out if the asset works well in-game. There are all kinds of cheats we do to get something done in time. monster has it right, it's the result that matters.

I think this is a huge issue. It's the portfolio piece vs. production asset issue. There a lot of things people do in highpoly that take way too much time, that essentially becomes completely wasted when the texture is baked, compressed, and shown in a normal resolution. Shortcuts and hackery are win on the job!

Michael Knubben

in I_R_Hopo's example, I would've used Polyboost/Graphite Tools' Flow Connect before cutting into the pipe, so as to minimise warping from having to weld things afterwards. So you're basically subdividing it locally so as to support the circle better, without having to quadruple the detail in the entire mesh.
I seriously love Flow Connect, it's such a time-saver at times!