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As CGI tools emerge as a powerful force in experimenting in animation, the artistic and technical challenges meet them head-on. In this article we will interview the team behind the cloth/cape work done on the 3D CGI short MAJOR DAMAGE ™ © 2001 Chris Bailey.

Early on in the project, the creative team knew that they wanted to stay away from using flowing cloth elements because this is typically a difficult and time-consuming effect to animate. But of course the show is about a superhero, and superheroes have capes.

“Historically, the complex simulations required to generate believable animation for cloth have been beyond the reach of most computer animators. In the past few years, most high-end production facilities have developed their own internal solutions for clothing simulation, but these have been out of reach for Independents and individuals. Now, with Maya’s cloth tools, even a tiny production like Major Damage can use cloth simulation techniques, and Maya’s tools are even finding their way back into those larger facilities to replace previously proprietary solutions. -Doug Cooper, CG Supervisor

Being that MAJOR DAMAGE is an independent short, time and resources were limited for extensive R&D. So the team began work with what they could use straight out of the box. Stephen Krauth and Stuart Seldon were the first on-board and together they came up with the majority of the cape process for the show.

“Setup was a problem. In the beginning at least, we weren’t able to figure out how to use preconstructed cloth models and import and place them into scenes. As a result we had to construct the cape for each scene, with a pretty streamlined process; we imported curves, made the cloth and did a bit of hand tweaking of vertices before starting the simulation. There was probably a better way to do it but we didn’t have time to find one.” – Stephen Krauth

“Before cloth was a part of Maya, the only thing available was soft body dynamics. Maya Cloth greatly simplified the process.” – Stuart Seldon

Below is the cloth/cape step-by-step process used on MAJOR DAMAGE:

1. The character animation was “baked out” into a series of frozen models, one for each frame, that we could scrub through quickly – instead of having to compute the character’s expensive deformations over and over.
2. The cape clothing “pattern” was imported as a set of Nurbs Curves, and positioned over the character’s shoulders. We generated cloth panels from the curves, and stitched them together to make a complete cape.
3. The cape was then “relaxed” onto the character’s shoulders, using a “shelf” to keep it from sliding off the character’s back.
4. After relaxing, the ends of the cape were constrained to the shoulders, and the shelf was removed. The simulation of the entire scene was then run to animate the cape.
5. Melvin’s cape was a little more complicated because instead of being glued to his shoulders, it was tied in a bow around his neck. But the basic process was the same.

As the project moved along, the cape team got a few new animation hands, Alex Bryman, Walter Schulz, Karen Smith, Tim Ryan, and SID. CGI animation is a young art form, and experimentation, even with established tools, is inevitable. Hear how these teammates learned, used, and trouble-shooted their way through the cape process.

Alex Bryman – Cape Supervisor

“Wow, where to begin? Maya cloth was able to capture very realistic cloth simulations with minimal effort in the setup stage. With a few curves, a garment object can be created which is then ready for simulation. Once the cloth exists, it is very easy to play with the variables and make the object react to the environment the way you want, whether you need it to be more flimsy and fluid at times when actions are simple, or be less flexible at times when you need it to be resistant to fast actions or exaggerated animated movements. Also, Maya Cloth really understands the physics behind the way a cloth object should react in the real world and can sometimes give fantastic and realistic results in one or two tries.

The problems I ran into while using Maya Cloth were that, like all things in computer created environments, they only have a set of rules and restrictions to guide their animation; they are not actual physical objects in a real space and thus do not always do what you hope or expect them to do. Interpenetration is the number one problem I ran into. I usually fixed the problem by adjusting the offset value on the surface object, or sometimes even tricked it by creating an invisible surface for the cloth to react to just above the visible surface. Depending on the camera angle, you could sometimes get away with having the invisible surface object quite a distance away from the visible character, and not be able to tell there was a space cheat going on.

Finally, most other problems I ran into were CV’s attaching themselves to strange random points in space or CV’s crumpling into big ugly messes around the constraints as the animation progressed. Usually, you play, tweak and yell obscenities at the computer, but when all else fails, you can usually resort to going in and keying each unruly CV, one frame at a time. It is a lot of work, but at that point it is usually 3 in the morning, and you are just happy to have something that is finally working.

Everyone finds his or her favorite tricks when working with cloth, but my best friend was gravity. In the Attribute Editor, you can play with the force of gravity in the X, Y, and Z directions. Because I wasn’t able to physically pull and wrap the cloth the way I might have wanted to, I found that by playing with the gravity and strategically placing constraint points to hold the cloth in place, I was able to get a variety of effects ranging from wrapping the cloth around his neck in extreme action posed shots, to keeping the cape from flying over his head or doing other “unpretty” things during the animation. When in doubt, I messed with the gravity as both a first and last resort.

My favorite thing was seeing my hard work result in a realistic effect. Seeing the cape on Melvin not only react to his movements, but seeing it contour over objects on the floor as he walks makes you feel a bit giddy in the wee hours of the morning. There are endless problems to stumble across, but there were so many skilled people working on the project, you always had someone to turn to ask for help or brainstorm with. It seemed like everyone who worked on this project did it because they really loved the process and it really makes a difference working in an environment where everyone loves what they do. This was a team effort from beginning to end, and we definitely had a fabulous group.”

Sometimes on projects, especially independent films (Indies) like this show, some find that they need to create alternative processes that work best for them to execute a certain end result. In a studio environment, which is driven by teamwork and structured processes and pipelines, this is generally irregular and highly discouraged, but for Major Damage it opened an arena for animators like Walter Schulz to work at his best.

Walter Schulz

“I’ve been using Maya Cloth for 2 years now, and I believe it is the best cloth simulation solution on the market, since it’s early release. My work on Major Damage consisted of creating and animating capes for the character of ‘Melvin’ as well as ‘Major Damage’.

Most of the shots were relatively easy to solve, as we had a workflow already set up. However, on the Major Damage character I had to devise a way to create the cape in a different way as we had stipulated, because the shoulder panels kept coming apart from the rest of the cape, and since I always received the scene with the collision objects already baked there were no functioning scripts for the cape to work according to the guidelines. I simply created the cape with curves traced over the original ones, which was our template to work with, and made 3 panels; the ones on the side run from the shoulder pieces and the one in the middle from the neck down. Then I created seams between them to make it one single piece. In some cases I had to vary the seams’ tension to give the cape a more natural look and avoid a crease.

In one particular shot, I had to animate a cape with Melvin laying on his bed. His hand was very close to his face, actually touching the face, so whenever the initial simulation of the cloth started it would get caught in that area; if I ran it between the shoulder and the arm, it would get caught during the calculation of the animation.

That shot was the hardest I got. The way I worked around it was to set collision priorities to the hand and the face, so the cloth ran smoothly between. Also, as Melvin stands up his right elbow makes a sharp move that always made it interpenetrate the cape. During those 23 or so frames, after adjusting the collision depth without any success, I had to manually adjust all the vertices of the cape in that area to a position where it wouldn’t collide with the elbow. The solution was to make the vertices look smooth without any abrupt changes that would eliminate the effect.

After I was able to make the elbow look good, I began to check the rest of the cape and I realized that it was also colliding with the shoes and other areas, so I proceeded to correct the rest of the cape manually until I got the look I was after.”

Tim Ryan

“The main problem I had with cloth on the cape scene I worked on was getting the simulation to keep up with the fast movement of the character. I know you’ve already heard this, but it was a big hassle! I had a short number of frames to work with and the character of Major Damage was flying though the shot really fast. The part of the cape that was constrained to the character was, for the most part, staying with him. But the simulated part was dragging behind to the point that it was still at the starting position at the end of the animation.

I asked several people how to solve this problem, and they suggested that I add frames before frame 0 and animate the character to gradually build up speed. Although this worked for other scenes, it just added additional problems to mine. So I took a different approach and turned up the stretch resistance. I also found it was better not to let the cape settle on the characters back. Instead, I left it at a slight up angle and decreased the density. Also, Karen Smith figured out that we needed to increase the shear resistance to keep the corners from being too pointy. And turning up the air damping gave us the desired flapping effect.”

Karen Smith

“After doing a lot of scenes, I noticed this very predictable behavior when the cloth first starts out with initial movement. If the character is moving fast, it wants to sort of stretch out, then snap back up, like an elastic band. But once it goes through this little “freak out” thing, it acts great. So I’d give the animation “pre frames,” usually between 5 or 10. I would translate the Major Damage character back a ways, let him fly, let the cloth freak out, and by the time he’s in front of the camera, he’s looking like nothing ever went wrong.

Another trick I used was to put a mesh constraint on the entire cloth object. Sometimes, depending on the movement, it will be solving along beautifully, then you’ll hit a frame that just will NOT solve. So I’d key the constraint at 0 on the frame before the problem, 1 on the problem frame and 0 on the following frame. The cloth will hardly move when you do this but if you only do it for one frame no one will really notice; afterwards it goes on fine again.

There were a lot of different ways to keep the cloth from going through the body. Since we used baked surfaces, sometimes I’d take a patch, duplicate it, make it a collision object and just translate and key it a little further from the body; then go back, truncate and re-solve with it thinking it was colliding with the duped patch, then just get rid of it. Just the little extra push it needed.”

Michael Mancini aka: SID

“There are many advantages to using Maya Cloth as opposed to animating cloth using other means such as skinning, blend shapes, or soft and rigid dynamics – it’s great… I haven’t seen anything that can produce as realistic cloth motion as Maya Cloth yet. I’ve personally experimented with other methods in Maya – and it just doesn’t come close. Yes Maya Cloth has some problems, but over all it’s advantages out-way anything else. I’m not just talking about garments and clothing; cloth can be used for other things as well. I’ve used it as rope, hair, even as an invisible constraint that something else is constrained to. Cloth is just so versatile, and except in the areas of fast animation you get great results.

Like several of the other cape artists, I had a lot of challenges with the rapid motions that Major Damage was going through. The way Damage hurled his ball and chain around and launched himself over the Tikis was great — just too fast for Maya to calculate very accurately.

So how do you trick a complex piece of software into doing something it naturally can’t do? I used a lot of techniques to get through my shot, including adjusting the collision priority for different surfaces of the character throughout the animation, sometimes adding full mesh constraints to the entire cape, and even using Artisan to sculpt some fixes. I used the Paint Attributes tool to adjust friction and density throughout, so the cape didn’t look like a piece of cling wrap on a piece of meat at certain points.

To make the final touches, I ran through the scene frame-by-frame looking for little pops, or weird folds in the cloth and smoothed them out with the Artisan tool and used the “Update Cloth State” command to basically save the changes to the cloth cache file.

I think the best part about the whole thing is how it was brought together, artists and animators from all over -communicating and working together. I also met a few new friends to chat with via email every now and again- hopefully someday we’ll all be co-workers! All in all for me it was a great experience, especially to see how things operate on the grand scale of things in this industry- knowledge only gained by participation.”

Doug Cooper (CG Supervisor) — addition

“One thing that really saved me at the last minute was how well Maya Cloth integrated with the rest of the Maya application.

In our last few days of rendering, I was putting together a shot with Melvin on the bed. To get things done quickly, we had given the shot to the cape animator before the final layout had been completed – they were working with just a plane for the top of the bed that Melvin was sitting on. The cape simulation matched to this, but when we put in the final bed, the cape stuck off the end of the bed without falling down, as if it had been over starched in the laundry.

We didn’t have any time to re-animate the cape, so I thought we were going to just have to live with it. But then I thought of an idea, and built a lattice to bend the end of the cape over the edge of the bed. I only had to sculpt one lattice position, and it stayed put throughout the shot, deforming the moving cape. Whenever the cape got close to the edge, the lattice bent it on down, and it worked perfectly. What would have taken a day to send back to the cape animator and re-simulate took me less than 15 minutes to fix because of Maya’s fully integrated tool set”.

What could have been better?

“One of the areas of Maya Cloth that I believe could be improved is calculation time. Sometimes, depending on geometry and the number of collision objects, the solving time would be really high per frame. I was able to bring the time down with some tweaking and by avoiding certain objects that weren’t necessary for the collision.” - Walter Schulz

“By far, quick and immediate movements were some issues that could use some improvement. In a lot of the scenes Major Damage is moving VERY fast! Learning how to wrangle the cloth to behave during those shots was the hardest part. Work-arounds were constraints, keying them on and off at different points, keyframing properties, and when things got really out of hand, just breaking up the scene in order to let the cloth relax just a little.” - Karen Smith

“When I felt everything I tried was going wrong in Maya, then it became a trial and error process of inputting different variables. It was more of a mathematical process vs. an intuitive artistic approach. I do not know if it is possible, but it would be great to be able to have some sort of pull tool or something where you could lift the cloth or pull it back and continue the simulation from there. It didn’t seem to like getting it’s cv’s tweaked and then being expected to continue to simulate (despite updating the cloth state). I don’t know, it just felt like when things got their most ugly, I wished it was made out of clay so I could reach in, correct the flaw and continue on. I guess I would like a manual over-ride clay tool option please.” - Alex Bryman

“Hmm! How can Maya Cloth be better? Well, if it could calculate animation that moves large distances in a short amount of time that would be great. Other than that, I have ideas for things that could make useful tools that could aid in how cloth solves or ways to manipulate it easier in certain situations… Other than that I feel cloth is progressing quite nicely.” - Michael A. Mancini / Sid

Working on the fly to hit a production deadline is commonplace in the CG industry. Studios and quality projects demand workers who can jump right into the job and understand how to make it work and look good, many times through troubleshooting as they go. Let’s hear what skills are suggested from a caped crusader (Mike Mancini/SID) and one of the show’s Maya trainer/troubleshooters (Vicky Snyder) before being hirable for CG Cloth.

What skills or background could help someone interested in doing CG cloth work and art?

Michael A. Mancini / Sid
First and foremost you have to want to do it and learn it really bad. Maya especially is a program no one could master overnight. I found my Artistic background helped me out a lot along the way but Maya isn’t just art – it’s a tool. I know a lot about Maya in general, and know how to use it, but I’m still learning new stuff all the time. I’ve always got my nose burried in one or two of the actual manuals that ship with Maya (Yes, I know they’re very boring, and can be difficult to understand, but after your second or third time through, it starts sinking in). The manuals I’ve found have the best information for understanding how Maya works under everything you see, what and how the actual Nodes and Attributes work in relationship to each other.

CG has endless opportunities; you can create anything you know from life or anything from the deepest depth of your imagination. If you have no art background and can’t draw, I recommend taking some art history and figure drawing classes. I would recommend Film, compositing, even lighting classes as well. The better you understand what you want to create in life or imagination – it’s that much easier to create in 3D. Tutorials and forums are also another great way to learn and gather information. I spend, well used to spend, half my day on-line communicating with other Maya users answering questions and getting questions answered until I had to get a job to pay the bills! Now it’s once or twice a week if I’m lucky.

School is always a good choice as well. There are a few specialty schools out there that teach Maya and CG -ranging from basics to advanced courses. You can learn a lot at a school, but from my point of view it’s only a starting place. If you really want to be good at CGI that is Maya particularly, you have to be driven to learn more on your own – use what you learn in school every day as a stepping-stone to unlock the full power of what can be created. I spent a year and a half at a school called Ex’pression Center for New Media. Good school, very intense -I spent between 60 and 90 hrs a week there. Most of that time was behind a computer after class hours trying to learn more. I feel it’s paid off tremendously- and I haven’t run into anything I couldn’t get to work or a problem I couldn’t solve yet.

Vicky C. Snyder
“A combination of an artistic and a computer background would be ideal for working with cloth. Cloth simulations are computationally intensive. Having an understanding of some of the math involved can guide in troubleshooting speed issues. Maya Cloth, however, puts a layer over all the math so that an artist can embrace their creative side and focus on getting the look without running all the calculations. Life drawing is a great way to enhance artistic skills, especially that of cloth. Sketching drapery, or baggy clothing helps to determine if what you see on the computer looks real.

Cloth simulations are one of the hardest things to make look real in CGI today. Maya Cloth makes it achievable, but having a good understanding of the basic Maya package is necessary so that if a problem arises, an alternate solution can be found within the software. Learning the software is no easy task, but the resources are available. If you have the time and the dedication, you can learn the basics by going through the Learning Maya tutorial book. There are other resources available for purchase at bookstores, like Mastering Maya by John Kundert-Gibbs, et. al. The on-line documentation is a great resource for learning how to use each and every tool that comes with Maya. And classes are available at schools like Gnomon, Inc. in Hollywood, CA, as well as on-line tutorials that are downloadable from the Gnomon Workshop site and the Highend3d site.

By far the best way to learn is to try it out. Get in front of a computer and start simulating cloth! Try to help out on a project. And most importantly, don’t be afraid to ask questions. There are many newsgroups and listservers available for aquiring answers to your questions. Use them!”

With this input from the cape team on MAJOR DAMAGE, we hope some questions were answered and those interested in working in cloth are intrigued to dive-in and challenge themselves.