Digital Choi: Dynamics of a fantasy character

A large part of this project was designed to showcase my technical ability in rigging and dynamic simulation. So naturally I designed characters that utilized everything that I could throw at maya. the following page will cover all the dynamic aspects of digital choi. First we will look at my adventures in styling choi's digital coiffure using the dynamics system to help me along. Then we will take a look at the rigging aspects of the character and how I was able to use maya's muscle systems to get choi to perform digital acrobatics, and a series of math equations relating to the rigging of realistic armor movement. Then we will talk about the finishing touches of the character and how I used a secondary hair system to drive some jiggly dynamic straps that would hold the armor together.

Hair

Designing an appropriate hairstyle for Choi was difficult. After attempting to get what I wanted out of maya fur, I abandoned the grooming in favor of using the dynamics of the hair system to develop Choi's hairstyle. it started with a basic fill of dynamics curves with paint effects attached.The next process used the basic head rig I had devised and the interactive playback controls, then by moving the head to whip the hair around I was able to freeze parts of the hair into the look that I wanted. I also employed the lattice deformer as well as soft modification on the individual curve points, having the ability to work with a series of curves allowed the level of control that I was looking for and through a process of interactive adjustment, keyframe head tosses, and carefull adjustment of the dynamic properties. I was able to bully the curves into the messy, life on the road hairstyle that I wanted .

Rendering the hair

how the edge of the hair would read was super important to me. and it set a definate challenge as paint effects rarely yeild believable results. However, after less than adequate results attempting to retrofit a fur description to my hair curves, I was left with no other option. I found that by lowering the amount of hairs at every follicle it became difficult to maintain a full head of hair, but by enabling multistreaks, or cheap copies of the hairs you already have just cloned about the location of the folicle I achieved both a low render time,  a nice rim disruption, and the ability to simulate faster. making the hair both easy to work with and elegant to render.

Muscles

While thinking about the fast action shots that this character would need to endure, the rig needed to be the kind of thing that could withstand whatever torture that I was willing to throw at it. after seeing the need for dramatic poses and extreme positions Muscles were the only choice, while I was hesitant to throw valuable time into learning a new feature for maya to meet a heavy deadline, the few hours I spent investigating this new plugin paid off in full as I realized quite early on the versatility of this system, while it has a way to go I found this system allowed the deformations of my dreams on choi's upper body. giving not only flex movements but a subtle jiggle, and sliding motion that added a whole new layer of realism to the character. Starting this task required that I break out my anatomy reference and start planning the muscle groups that I would simulate. I started with the deltoids on the shoulder and got some pretty believable motion out of them, Biceps and Triceps were next the insertion points of all my muscles became the biggest challenge, because physically accurate placement rarely yeilded believable results. Funny to think that yet again what was wrong was actually right. The underside of the arms became a problem at this point and was cleaned up with the addition of the teres major, converting some simple geometry to act as Choi's ribcage also aided the deformation of the chest and gave the skin something to slide around. However the chest made some weird deformations at the top, so the last muscles in the system ended up being the pectoralis. getting these right was a real challenge, because unlike the rest of the muscles which mostly expand and contract in a straight line, the pectoralis has to wrap around the front of the ribcage as it expands or contracts. you can see in the image above my attempts at making this deformation sellable. all in all I think that muscles could be the future of rigs for me as they yeild a whole new range of possibility in the rigging process.

Armor

while the armor isn't dynamic special rigging concerns had to be taken to rig the armor like a machine but still allow it to shift and move on choi's form. this was acheived by rigging empty objects that were controlling the armor and enabling controls that would allow adujstment of the armor. for example we will look at the knee as it is the most straightfoward. the knee consists of a hinge joint(being a joint that really only bends on one axis), the armor knee called a poleyne is comprised of a solid cap and is connected to smaller plates that each allow for a piece of the movement. so all of the pieces of the poleyne are rigged to the thigh bone. the individual pieces of the armor are then connected to nodes that compute the rotation that each plate is supposed to have. allowing the plate at the end of the chain to move with the thigh and follow the rotation of the calf, the next plate up does the same but only follows 75% of the calf's rotation. Then the knee protector is more of a 50-50% rotation and so on. Often times in fantasy animations or films I see armor that is obviously rubber, or just designed/build/rigged to move in unrealistic way's. Wanting to preserve a sense of realism in my fantasy piece has definately set a bar that I must achieve, but I wanted it and I feel that with this collection of multiplication falloff nodes I have given the armor an extra hint of realism that may just be the difference between creating something so-so or something that makes the causual observer say, wow!

Straps

This piece of rigging would probably be the icing on the cake. I had seen a tutorial once describing the use of the hair system in rigging a robot to control hundreds of jiggly wires in the undercarriage of the machine. I took a similar path to create some leather straps whose purpose would be to tie the armor all together. I wanted the straps to be simulated to allow for plenty of great secondary action on my character. also I was unaware at the time how well the armor rig would work out so the option of standard rigging for the straps was ruled out almost from the beginning. The creation of the straps began with a spline IK joint chain,  a chain of joints that is controlled by a curve where every joint in the chain tries to stay in line with the curve. this chain is bound to the straps using a simple smooth bind. the chain is also rigged into the character. Then we create a curve by placing a point on the curve at every bone in the chain. The curve is then added to a dynamic hair system, and the created output curve is used to drive the IK spline. when we run the animation the bones follow the dynamic motion created by the hair system. constriants rigged into the character allow for the straps to move between the pieces of the armor like they were tied down.

Cloth

choi's upper body is covered by a sort of battle scarf that has attached to it the shoulder protection. it is intended for this to be a dynamic cloth object that will be constructed after the female character is created. Choi will lose this cover during his battle with the monster. While I didn't have time to work on this element this quarter, I still wanted to talk about it a little bit and will cover it's creation here as I develop this asset.  This will prove to be a difficult object since it has both cloth and metal plates in one simulated object. I have a few plans for how this could be done, but very little of it has been tested. as a cloth showpiece I look forward to this object being a great addition in the future. look for it in the finished animation!!!!