Killer Scorpion VFX for Clash of the Titans
How Cinesite Designed the Arachnids, Scanned the Location, and Helped the 3D Conversion Team
Simon Stanley-Clamp: Back in December 2008 we did tests based on a really loose description [in the film's script]. We’ve done eight-legged creatures before – spiders – so it wasn’t difficult to rig a rough rudimentary scorpion and use a digidouble we already had just to do a formative fight sequence of about eight shots. We were awarded the sequence virtually on Christmas Eve and hit the ground running January 5, 2009, working with [the film's visual effects supervisor] Nick Davis.
[Character designer] Aaron Sims scanned out five drawings we were given. They were not dramatically detailed, but they showed the scorpiochs in their environment. We got an idea of this palanquin on their backs that people could sit in. They showed that the armor was quite plated, that the stinger was slightly exaggerated and oversized, so it was a beginning for our designer. We worked up about 10 or 12 designs in Mudbox and presented those in various stages over the course of about three sessions with the director. I took the Mudbox models, posed them, rendered them, and did flat Photoshop boards for presentation. The director could say, “I like the claw on that one, the tail of that one and the legs of that one.” We kept remodeling until we locked the design for the middle-sized scorpioch, and then we went through the same process for the mother, the biggest of all. We had two sizes, and we extrapolated for the ones in between.
Next you had to turn those designs into 3D models.
The Mudbox models took us to about March, and at the same time we were working on animation rigs and walk cycles. We were fine-tuning the outward look, but the underlying skeletal rig wasn’t going to change – it has eight legs, claws and a tail, and an undulating body. So we were able to rig the scorpioch and start work on our initial animation. We did quite a few scenarios, and built up a little library of movies: a scorpion that would jump; a scorpion that would run; a scorpion that would stab its stinger through a figure and throw it away. Louis wrote those back into the previs, or “beat sheets,” which were these descriptive, blow-by-blow accounts of how a fight would work. We then took the Mudbox models into Maya and started to do the full build on those. Texturing was going on concurrently.
How did you steer the texture decisions?
It had to be organic. We had to be careful not to make it too shellfish like. Early designs leaned toward a lobster or a crab, so we backed away from making it too shiny and mollusk-shell like. We built up a library of textures. In March 2009 I got some more reference from the location, and the tone of the rock, the cragginess of the rock, was something else that we built into the textures of the scorpiochs. They are a combination between the hard shell and the softer, muscly bits ‘ a bit rhino skin or elephant skin, with gnarly and very deep textures.
What was the location?
It was in Tenerife [in the Canary Islands]. We went there just for a reccy, a two-day scout, back in March. It’s a national park 2000 foot up the base of a volcano. We divided out three areas where three separate fights took place. A fight with the smaller scorpion and the two brothers and then the bigger crew led by Draco in more of a valley environment, and then the other fight with Perseus, Io, and a couple of the other soldiers. We took a lot of reference photos and 360-degree panaromics, brought those back to base, and piped that into building up our library of elements and starting to texture.
The scorpiochs have to break out of the ground, and initially I thought the ground would be really hard, almost like cracked mud, and when the scorpions broke out it would shatter. Having visited the location and shot a little DVCAM footage, we knew it was nothing like that. It was little pumice stones with dust on them, and when you kick the stones dust flies everywhere. Peculiarly, if you bury something and pull it out, the ground reforms and pulls itself back together. You’re not left with craters. That was one big area where we had to change the animation. The ground had to be much finer, very dusty, and that led to a whole new pipeline for fluid textures, dust, gravel, and sand.
What software were you using for fluids and particles?
Was principal photography for the scene happening while you were working on the animation?
No, we had a good lead time. We started January 5 and the production shot for a month in May. Pre-vis was closely locked around March. The stunt coordinators were working to the previs, and they built a proxy set in the warehouses at Longcross Studios. They had rehearsal rooms with cardboard pillars and tubes and ramps and rostrums where they measured the location out so they were able to run around and do the moves and rehearse. They even built a proxy scorpioch. It’s a nice rig. One of the stunt guys played the scorpion and had carbon-fiber extended arms with claws on the end to our measurements. The actors knew what to jump over and how far away they could get and how close they could get to the scorpioch. It gives you this whole spatial awareness and you’re not guessing on the day.
What happened next? Was it a matter of getting live-action plates in hand?
We went out a week ahead of the shoot and surveyed absolutely everything. We took HDRI photography of the three locations as well so we were really covered. The timespan of the fight is minutes, and the lighting is a rocky desert at noon. In theory, the lighting shouldn’t change – but it’s a 12-hour day. We shot from 7 a.m. to noon, then physically switched the set around and shot from 1 p.m. to about 6 p.m., when the sun went behind the volcano. We covered that a week before, shooting HDRI on the hour every hour throughout the location. So before shooting started, we had HDRI of all the locations and all the potential lighting scenarios. We could DP it and go, “We need 11 o clock HDRI.” It’s done.
I also shot specific HDRIs at the end of each take. If a poly was flown in, or some sort of diffuser, we had reference for that. On two occasions a little bit of additional lighting was put in. We surveyed absolutely everything we could, and it was pretty accurate. The set was still going up in that final week, so we’d do a day of surveying, and then come back the next day when another bit of the set was in and update our survey. We knew we’d have to replace things, add things, and build additional columns. A day before shooting, when the set was as close to finished as it would ever be, we got a LIDAR scan of the three locations.
And you remained on set for the shoot.
Yes. We were shooting three units simultaneously. Nick Davis, the overall supervisor, was on one location, and I covered whichever one he wasn’t on – and occasionally both of them. Nick [Davis] might go off on the helicopter unit and I’d cover the other units.
What kind of material did you start getting from the set right away?
Production turned all the plates over as 2K scans as soon as they could with a rough cut locked. They had always been working to the previs, and at that stage the previs existed as three fight scenes. They turned all those plates over, and we did rough tracks, not of video plates but of film plates, so it wasn’t throwaway data. Anything that made the cut we had tracked at full 2K resolution. All the survey material, the help frames, and the LIDAR scans all made the tracking process easier.
When we blocked out all the shots for the initial fight sequence, it came in at something like 12 minutes long, which is clearly too much screen time. Editorial made a decision that it doesn’t work because a) it’s too long and b) it’s too disparate. They took the three fights and edited them into one continuous, long fight with continuous overlapping action. The fights swing in and out of each other, and if you hadn’t seen the separate fights you wouldn’t be aware of it. At the end of the day, it’s lots of men in skirts fighting big scorpions and you don’t have a good idea of the chronology.
To help that out, we modified some of the scorpion designs. The smallest scorpion became jet black, almost like a beetle. There were two middle-size scorpions so to distinguish we stuck with the original design, which is slightly brown, and then modified the one that Draco fights and jumps on the back one to make it a bright, sandy orange in keeping with the rocks it was fighting amidst and then the big scorpion was the mother scorpion, which stayed as it was. That brought the sequence down to something like eight minutes – still a lot of shots. The cut was getting close to locked. We got rid of the shots we weren’t going to work on and then worked on the shots in the cut, replacing the proxy grey-shaded scorpion with our model, with full displacement and full textures.
And there were a couple of shots with digital doubles in them. We built 14 digi-doubles, and only two of them were hero characters. The others were smaller ones that ride on the back of scorpions. There were two shots where it was going to be a takeover, but at the end of the day we did them as digidoubles all the way through because physically the actors or stuntpeople couldn’t do it – a scorpion picks them up and throws them off into the distance, or the scorpion hooks the guy up and throws him into the air and then crashes him back down to the ground.
Did the last-minute decision to go 3D affect you?
It did. We set up a subteam. The way the decision happened was quite weird. After the trailer there were a couple of shots, and I actually remember saying, Ã¢Â€Â˜This would look spectacular as a 3D shot. Ha ha!’ In December they started to talk about it. They said, “It’s going to happen – they’re doing tests out in Burbank.” Just before Christmas, they said, “No, it’s absolutely not happening. Delivery is as usual. Get cracking.” We came back after Christmas and then a week into January, they said, “It’s absolutely going stereo.”
Framestore, MPC and ourselves had a conference call with the [3D conversion] vendor, Prime Focus, who said they needed mattes and masters and any ancillary 3d passes. We delivered those and, in some cases, clean plates as well for them to push through the conversion.
We set up a small team so it didn’t distract from finishing other shots. We would revisit shots and extract those mattes and masters with camera moves on, and any additional camera shake. We did a lot of work adding dust hits, lens hits and other post effects to make CG shots look authentic. There was some debate about making cleaner versions, because something sticking to the lens wouldn’t translate well to 3D.
Did that actually happen?
It didn’t actually happen, no. [Laughs.] We did supply shots with stuff on the lens.
Was Clash of the Titans a tricky job overall?
It was more tricky than we had anticipated, and it took a while to get right, but once we had nailed it I think everyone was pleased, especially with the effects of dust and gravel, etc. Simplistically, the Scorpiochs land, they generate gravel, the gravel generates dust, and the dust generates sand. You’ve got these nice textures and atmospheres to flesh out the shots and tie in with the live-action plate. Every shot had somebody off camera with a bucket throwing dust in or a broom dusting up the shot. It really worked for the backlit dust ‘ it creates lovely, volumetric god rays. The DoPs love that look, and that’s what we have to match. That’s our job.