Hand-modeled weld line, but how to fit it?

[Tekergo]

Hi!
I want to make a good looking weld for my model. Sculpting and those random blob generators didn’t really work, as with that the weld looked like… like if i was doing it in real life (a mess)

So, i had the idea to make a weld line from a simple mesh and and array modifier, added some randomness to it, will be perfect with some tweaking.
My plan was to snap it to a curve (or even get a curve from the intersection of the parts), and then adjust it slightly (size, shape, tilt, etc.)
And then, when the line is in good place, i would join it with the main model, and actually merge it into the topology. (or maybe just add it as prop over the joint, without merging with the mesh, not perfect but might be good enough)

However, when my plan failed, is that it’s basically impossible to handle it perfectly with a curve. The intersection of even just two cylinders is so complex shape, and the line has to be on so many different distance from the actual intersection (the thickness of the weld), with different shapes, etc., that i just can’t control it well enough. Also even if i could do it, would be way too much time with a probable not good looking result.

So, my question is, given this base, does anyone have any ideas, anything as a brainstorming, what else could i try to fit it perfectly on the surfaces? The ideal would be that both edges of the strip fitted onto the surface, kinda like a shrinkwrap but only for the edges while keeping the shape, obviously.

This is the basic mesh:

To make this strip:

It was my first try, just a brute force “fill the gaps” method, but this way you might understand my plan better:

With or without the sides, it’s very difficult to fit everything, especially since controlling bezier curves in blender is not always perfect

If it worked, the final result would certainly be better than any other methods, the weld would look truly professional.
For now, i would like to avoid a bump/displacement map method, my hope is to have it as a true model, with a really high level of detail.
Not sure if geometry nodes would help anything with it, I’ve been using blender for 15+ years but my knowledge in that area is very shallow.
I would really appreciate any ideas, as my brain is already cooked
Thank you very much!

[BG_Division]

@Tekergo

For now, i would like to avoid a bump/displacement map method, my hope is to have it as a true model, with a really high level of detail.

Displacement IS real geometry, if you find a good texture then it could be a perfect way to do it.
Or, as a perfect craftsman welder, you can directly sculpt it, why not.
Also, I see there are some add-ons that can do it but I don’t use them.
Below you can find an old but very good texture to be used for displacement (the GiantCowFilms user answer), I used it several time in some of my projects:

How to create proper displacement for weld joints?

You can use it in many ways, to displace the strip and then stick it to the object using the shrinkwrap modifier, for example.

[Tekergo]

Thank you very much for your answer!

I think i figured it out. I’m writing it down in case someone finds it useful in the future.

First, i made a loop like this, simply the shape of the contact edge.

Then extruded it, and added a shrink wrap modifier. The trick is, that on the top/bottom part (in this case) the weld line is about 45° steep, so i made it that way. But since the middle parts are now have a different width, with the shrink wrap enabled in edit mode, i adjusted it so the edge lengths are more or less the same all around. This new strip is exactly where the weld line would be, nicely fitted to the surface.

Then, taking this strip’s middle line i can make a curve, that enables me to use for deforming the weld line. This is in the correct position and angle, only have to tweak the tilt and some distances, but already in a good place.

I still have to figure out how to implement a nice weld line here (maybe it’ll indeed be a displace modifier now that it is separated from the main body), but with a bit of shrink wrap + data transfer magic, this is how a simple strip looks:

I’m sure it will need a lot of adjustments but this technique for finding the middle loop is the key. It’s so simple, but i don’t know why didn’t i think of it earlier

Thanks again!

[BG_Division]

This is a quick setup with the texture a linked above + shrinkwrap + displacement (it took 3 minutes):

[oo_1942 (Kim)]

The attached image is the use of welding addon.
As you can see in the image, you create one pattern and apply it over and over again.
This can be made by transforming the cylinder.

[Tekergo]

Thank you!
My problem is not doing the displacement, but making the strip blend nicely with the main body.

It looks nice in material preview mode:

But when rendered, there are a lot of shading problems, edge artifacts, etc.

The visible (jagged) edge comes from the intersection of two surfaces, that faint banding is from the data transfer modifier.

Maybe i’m just asking too much from blender and it’s not possible to blend two separate geometries into one, without having some shading issues. Without of course, merging the mesh properly, by hand.

weld_test.blend (150.7 KB)

[Tekergo]

What’s the name of this addon?

[oo_1942 (Kim)]

This is Welder.

Welder

[BG_Division]

I can’t reproduce your issue on my own.
Sorry but just to know: why you need to use the data transfer modifier. Welding strip and pipes are different objects, also in real world they looks as 2 separate things:

[SoundDifferent]

Whi render you are using? I cant see such artifacts at least in eevee if i try to render it.

[Tekergo]

I want to use the data transfer so the strip becomes the same object, although different material. I mean, no gaps, no shading bugs, one “solid” object, as in real life.
I attached a blend file in my previous comment, so you can see what i was talking about.

[Tekergo]

Indeed, in eevee it looks perfect, but i’m using cycles

[BG_Division]

Ok, ‘De gustibus non est disputandum’
I downloaded your file and played a bit with it, below you can find the file:

weld_test_mod.blend (191.0 KB)

My test renders are fine, sometimes jagged edges are still visible ONLY in 3d view (especially in solid and orthographic view, but renders will be ok (at least in my test…)):
render

3dview

I used mixed techniques, some of them from this very nice video because a little bit different from my usual workflow/targets and I’d like to try them:

Connect two objects using the Data Transfer modifier, it's cool!

Hope it helps

[Tekergo]

Thank you very much!

I tried to back-engineer your version, and the only significant difference I found, was the base geometry. I mean, simply copying the modifier/vertex group system won’t help to solve those issues. Shaping the base mesh differently does seem to help a lot.
Still not perfect, but way better than before, and that tiny crack and shading misalignment won’t be visible on the final renders.
Thank you, again!

[BG_Division]

@Tekergo

I tried to back-engineer your version, and the only significant difference I found, was the base geometry

Not only that, just some others: SubD before the first Shrinkwrap and vertex weight.

But the truth is that there is not a unique solution that could be used for any situation.
It’s always a ‘Improvise, adapt, and overcome. Then adapt again’ moment… (Gunny cit.)
You can play further with it to improve the effect, mine it was just a start.

@Tekergo

that tiny crack and shading misalignment

In 3d view is normal to have some ‘artifact’ in case like this, it cannot have the same quality as a real rendering.

[Tekergo]

Yeah, exactly that’s why i like Blender. There are so many ways to do everything, kinda like real life crafting. You have a couple of tools at hand, the rest is up to you.