How I approached animating a tripedal character.
Question: “How do you research locomotion of a creature or animal that doesn’t exist in the real-world?”
Answer: You combine physics, logic, and creativity to come up with something that looks awesome!
Tripedal movement (something that uses 3 legs to move) is not a popular form of locomotion. In fact, no animals or creatures on Earth have three legs. So, this was definitely a challenge (which is why I love animation)! A hearty Google search provided some interesting reference material:
| Star Wars (prequels) - Droidekas |  |
| World of the Worlds (2005, Spielberg) - tripods and aliens |  |
| Borderlands 2 (video game) - creatures called "Crystalisk" |  |
| STriDER (research project by RML) - wildly unique robotic locomotion |
All of these examples had unique forms of tripedal movement. Droidekas had small, jerky movements. All three legs are equilateral and spread evenly apart. However, Droidekas cannot run or move quickly (watch the prequels if you don't believe me). In order to get Droidekas to rapidly deploy, they are designed to roll into a ball-like shape and move like Sonic (the video game character). Whoever came up with this design solution is a freakin' genius!
The Tripods and the aliens in War of the Worlds both had different takes on tripedalism. Tripod (the alien machines) legs are not quite equilateral. The back leg is slightly longer than the two front legs. Also, the two front legs are positioned more like arms while the back leg serves more as an actual leg. When walking, Tripods resemble gorillas (notice how the front two legs move more like shoulders than thighs). All three legs have a tube-like design (like a rubber hose), allowing for more graceful and less robotic movement. The aliens are similar, but they have much longer back legs, which makes it easier for the back leg to pass between the front legs.
Crystalisks (Borderlands 2) locomotion is similar to Droidekas. They can’t run, but they can move forward at a moderate pace. Their equilateral leg design most resembled The Gardener’s.
STriDER (the research robot named after a Half-Life 2 tripedal creature) stands for Self-excited Tripedal Dynamic Experimental Robot (I think S.H.E.I.L.D had better luck with acronyms). Obviously I couldn’t use this type of locomotion, but it was fun and creepy to look at!
Question: So I did my research, now what?
Answer: Make it cool and believable.
The character design is awesome, but it needed to have functionality (even in the fantasy world). Being a tripod had to give The Gardener a strategic advantage in combat. Believability is critical with an audience (especial with modern-day movie goers). I can’t count how many times I’ve heard someone comment on the “why” of a design in movies.
“Why do Jaegers (Pacific Rim) look like humans in armor?”
“Why are ATAT Walkers(Star Wars) designed so top heavy?”
“Why didn’t the aliens who built The Gardener give it four legs or six legs?”
“Why didn’t Darth Sidious try to fix his face after that little electricity incident with Mace Windu (just kidding)?”
There’s a hazy line between what audiences will accept and what they will consider “unrealistic” or down right stupid. Everyone has a different opinion (also another reason I love movies). Why does The Gardener have three legs? Because that’s how he was designed by the Art Director! My job is to make it cool and believable!
Question: How do I make it cool and believable?
Answer: Start animating and experimenting, duh!!!
I decided to try out a few patterns and started coming up with what I affectionately called the “Z-pattern”. It’s a mix of Crystalisks (BL 2), Tripods (WW), and my fingers moving across the desk (no joke).
The tricky part was getting the back leg to move faster than the other two whilst retaining a good sense of weight and scale. A good trick to making something look bigger in animation is to have it move slower, which makes it look heavier. The Gardener’s back leg takes a step between every step of the front two legs. In addition each step lands closer to the front leg that’s about to move forward (trust me, it’s confusing as hell). Take a look at this video to help you understand my babble.
Question: Can The Gardener run?
Answer: Yes, but you have to be careful.
What do I mean by “careful”? I mean that running The Gardener in broad daylight across an open field would look comical (I’ve included one of my run tests to prove it). The Gardener is here to wreck Floyd’s day, not to act like a clown at some kid’s birthday.
Instead, we used the cluttered area of the spaceship hanger to get The Gardener to jump, crawl and stomp in pursuit of Floyd. During the tunnel chase, lighting has a big part in get the animation to look scary and intimidating. Basically, we had to get creative, which is what I like most about movies!
Question: “Did it work?”
Answer: You decide!
Be sure to watch ÆtherEdge(proof of concept) when it premieres later in 2013! Thanks for reading!!!
-Andy