Deep Cuts: Forging the three elven rings for The Rings of Power

Outpost were thrilled to work on such a creatively challenging, FX-heavy sequence that was integral not only to the series but to the wider Tolkien universe. Outpost VFX Head of CG, Joan Panis, talks us through the team’s work.

Faced with such a big FX sequence, what initial conversations were had around delivering this important story point?

We approached it by breaking it down into a few things. VFX Supervisor Richard Clegg started by collecting a lot of references of molten metal in refineries and looking at smithing where we can see how the metal begins to melt. We sat with the clients and went through these to start figuring out what type of effect was needed for each part; we had the fire in the forge, the melting dagger, the mithril, and the melting of the three different metals, each of which needed to have a different appearance.

So we asked ourselves, how would that all look? We started with the different types of metal and the different types of properties for each. The whole thing had to melt, and we had a lot of reference for that, but the real challenge was how do we separate them within one area that looks good. There was a fair bit of back and forth on that and we went through some concept art to try and nail down the different looks. 

At the same time, Amazon released the first teaser trailer which was all filmed practically with macro photography and it was a high, super up-close shot of liquid running through wooden runnels. We used a lot of that as reference and what we really took from that was when the molten metal starts cooling, it creates like a skin, similar to what you get on milk if you leave it out.

That became a big part of what we had to look at; getting that skin, that crust on top and that’s how we decided to define the three different metals: how much of that skin and the properties of that skin and its cracked look between all three.

From a more technical viewpoint, can you talk us through the process that you and the team went through when creating the fluid sim?

There were a few different setups depending on what was needed. We had the melting dagger shots where we converted the dagger into lots of particles. We used a FLIP simulation and transferred all the attributes, the UVs, from the original model to particles for the melting behaviour. We had noise going through to try and get the timing right of triggering the viscosity change of that FLIP and then as the viscosity was changing, we played that in the shader as well.

[Outpost Lighting Lead] Guillaume Depierre and I built a molten metal shader that was red with noise attributes to create cooler areas, so you get the nice texture look of not just yellow, but ranges of yellow.

So that was one type of liquid simulation, then we had a standard FLIP where we filled the pan with liquid and we poured it into a bowl, but one element of molten metal is that crust we were talking about earlier. So we had our CFX artist, Kira Urquhart, who created cloth sims to go on top of that sim that glided and fell into place to create those little sections of skin crust. 

We then had the liquid in the spinning bowl that needed to move with the centrifugal force and expand out to the edges. We did a few different ways of having the liquid expand before we settled on the one you see in the series.

And whilst the liquid is spinning, they drop in the mithril and so we have a splash in the liquid which also needed to react to the variation in heat, so we needed to make sure that there was an attribute that tracks for shading, which means when it hits the liquid it’s much more glowy and heats up. We had heat attributes that would drive the shader colours. That was a mixture of getting a FLIP and then making sure we get the rest attributes on there so we can track the texture onto the liquid.

Then, finally, we had the separation of the liquid into the three different metals for the three different rings. For this we used one big mesh that we made from the last frame of the metals once it’s spinning and we used that as a base. To start off this shot, we made a 2D fluid sim with three rings of colour: red, green, and blue. And we spun them so that the colours started mixing. Then we took that sim and reversed it so it was going from mixed colours back into the three separate ones. Then we transferred those FLIP attributes, the colours, onto the mesh and those would be masked for the three different shaders.

It took us a few iterations because it was looking cool, but something about it looked a little odd. We were discussing this shot for a while and in the end we reversed the spin on that attribute to make it lag instead of going forward, and it looked so much better.

Once we had all of these simulations in place, comp took over and added lots of lens flares and gave them the extra 2D love that really brought those shots to final.

How much of a challenge was the pouring of the liquid down through the elaborate funnels and into the mould?

This started with the scooping up of the liquid, so we started with the last frame of the attribute transfer again, and initially tried to do a simulation but because it was spinning very fast, it was really tricky. So what we ended up doing was just a simulation for when it was going along the scooper to get the splashing behaviour. 

When the liquid was travelling down the rails, instead of a FLIP, we used geo in the shape of a sausage to give us more flexibility with timing as it’s travelling. We moved it around in a layout pass to show it in context. That gave us our layout, shape, and timing.

In a few of the shots we’re looking at it side on, and with a FLIP you wouldn’t have seen the bulge coming out of the rail; it was all inside. So we merged our FLIP with our layout geometry and then worked up the shader.

Another little touch we added in FX, we did some fire sims and smoke because one of the things we took from the trailer was that as the liquid was advancing, it created small bursts of smoke because there are particles there or some dust that gets burnt up as it touches, and some static energy I’m guessing. These sparks happen automatically, so we added some of those elements in there too as it’s moving.

Then, once again comp added lots of elements on top such as heat haze distortion and more smoke to really embed the liquid sim in the shot. Our comp supervisor, Luddnel Magne, and his team's work was really great in helping sell this sequence.

Another thing we noticed from the teaser trailer was that the skin on the top didn’t move as fast as the more viscous liquid beneath. So through shading we created another layer of skin that would not move at the same speed as the liquid. We also played with the roughness of the specular, because obviously that skin is much more of a diffused surface and less reflective than the molten liquid beneath. So we put a pattern on the geo that would then be given to the shader that would follow that pattern. All of that was on the geo we made so we could control the speed of that skin versus the speed of the metal.

When you think back on this project, is there any one thing that stands out in your memory?

It was a really cool show, and the seqeunce was made up of really creatively challenging shots. I think out of the work we did, getting the texture of the spinning rings right was something that stays with me. We were working on it for a while and couldn’t pinpoint why it looked unnatural and I remember when we flipped the whole thing so that it was playing backwards, it was such an ‘ah-ha’ moment, I’ll remember that for a while.

Joan Panis is Outpost Montreal’s Head of CG with 20 years in the industry. Joan has extensive experience across various CG departments and on-set, with a deep specialism and interest in FX. 

Over the course of his career, Joan has lead VFX teams on highly technical CG sequences on high-profile film and episodic productions, including Disney’s Lady and the Tramp, Slumberland, WandaVision, and Godzilla vs. Kong.