Creating realistic organic characters can be considered like the "Holy Grail" for some CG artists. This "neo-realism" is based not only on the way the character looks, but also on the way the character moves, because they only come to life when you see them acting on the screen. Most of the digital characters that you see on the screen are able to move thanks to some very complex rigs, but their skin is deformed by muscles. The creatures that you may have seen in "StarWars" or "The Lord of the Rings" have these kind of muscle systems to simulate their arms bulging when they lift something, or simulating the fat around the belly or thighs.
Muscle systems are available for the major 3D applications out there, such as Maya, Max, or XSI, but they are usually very expensive. However, thanks to Judd Simantov, we Maya users are able to have a fully working muscle system free of charge. Before going any further, I want to clarify that I have never used any muscle system, such as Comet or MuscleTK, so I can't really make a side by side comparison between them.
cgMuscle is Judd's plugin for Maya that will allow you to create an entire muscle system for your character. To start the plugin, you simply run a command from the command line and the main window will open. When you are to create your bones, you have the option to create the inserts and roots as locators, or stick them directly to the bones, as well as the number of spans for your muscle. The "manipulator" button will allow you to modify the direction of the tendons, as well as the width and overall shape of the muscle.
As you can imagine, you can define the muscle flex and volume; this is useful to simulate the different kinds of muscles. Some muscles widen when you bend your joints (such as the biceps), while others only seem to slide on the bones (such as the Deltoid). The muscles can also be used for fat simulation. These muscles not only flex, but also jiggle when you animate them. This proves to be especially useful for fat simulation. A lot of Maya users around here will surely want to try this plugin with their favorite Poser figures (actually I am trying this one with Victoria 3). Imagine, for instance, that you imported your Troll figure, and you want to simulate the fat on his belly. You can easily do this using the muscle jiggle.
The main reason why you would use cgMuscle, is to create a muscle system for your character. For this you would need to build your skeleton and then attach the muscles to it. If you thought you would be able to use the Poser skeleton, or any other skeleton model out there, think again! You can only attach muscles to NURBS surfaces, which is a very big drawback, because it forces you to create a complete skeleton using NURBS surfaces.
The demo video features a preview of the skin modifier. This modifier will let you easily deform the skin using muscles. Judd has also added "sliding-over-the-muscles," so you will be getting very natural and organic deformations. Unfortunately, the modifier is not available yet so I was unable to test it. Even if you don't have the modifier yet, you can use the muscles as soft-skin influences or wrap modifiers to deform your skin (actually, I wrote a MEL script that will allow you to deform your skin with wrap deformers. You can find it in the Maya forum).
As I said before, I've never used any other muscle system for Maya, so I can't really tell you if this one can be compared to them. I found the creation method to be simple, but effective. However, when you have to manage the muscles, things are not so friendly. First you have to select your muscle from the roll-out list in the window, and then you modify it using the different operations found in the window. For most of them (such as the inserts or the manipulators), these can also be modified using the channel box. However, the command I used more was the "Initialize Length" operation, and that can be called only from within the UI window. There is actually a MEL command for it, so if you are a MEL-lover you can even write your own script that will perform the Initialize Length. These problems may not sound like such a big deal, but you will really think of this as a limitation as your muscle list grows larger (my current muscle system has around 90 muscles, and the roll-out list is not long enough to show them all. So I am forced to either enter the name in the window, or use MEL scripts to operate on my muscle). Keep in mind though, that this is the first release and there is a lot of work to be done.
I can't say whether or not you should choose cgMuscle over Muscle TK or Comet Muscle System. However, this system does include a lot of very nice features to help you with your character deformations, and surely you can't beat the price! It still needs some refinements when it comes to workflow, but if you know how to make Maya MEL work to your advantage, you will be fine till these features are added. I advise you to visit the cgMuscle website and try it for yourself!
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Animation Alley is a regular featured column with Renderosity Staff Columnist Sergio Rosa [nemirc].