How did I deal with…?

Simulating Maya Muscle as Skinning Method for a Human Character, Driving nHair and nCloth

The goal of this simulation is to provide animators with automatic deformations on a rigged/skinned character for a short film. I'm using the animation on the character as collision surface, and the joints as anchors for the simulations. This is what the short film looks like after post‑production:

I'm solving this situation in 2 steps:

1. Simulating the muscles, and
2. Letting the deformations on her skin drive the other 2 simulations (nHair and nCloth).

Muscles

The solution I'm developing here consists of simulating muscles mimicking the behavior of the muscles in a real human body. I'm starting with a rigged character, using Maya Muscle as deformation mechanism.

I'm linking rigging and skinning using Maya Muscle as deformation mechanism through:

• Maya Muscle using NURBS surfaces deforming in real time, simulating the behavior of real muscles, compressing or stretching from their anchors on bones
• My joints in Maya are rotating like my character's articulations, deforming the polygonal surface, and
• I am keyframing controls in a Maya Character Set, to rotate and translate these joints.

The advantage of using controls on a character set is that I can import/export the animation curves to similar character sets independent of the rig system they are using.

Before the animation process is finished, I am linking my NURBS to the virtual bones, telling the polygonal surfaces to react to the deformation of my NURBS muscle simulation, like here:

Other simulations

Once my rig has a functional muscle system, I can move on to implement other character specific simulations. In this case, I'm applying a nHair solution to simulate the long hair of my character, and nCloth to deform her dress, based on her skin deformations, using them as collision objects:

The advantage of this method is that I can take my simulations wherever my rig is, being careful to keep up with updated caches. Once the simulation on muscles, clothes and hair are cached, I can import my character into my lighting scene, and prep for render.

This is a simulation example for a character, but there are many other methods to calculate, apply and render simulations and VFX. Click on these cards to take a look at other case studies:

Grooming Human Head

Grooming a human head using XGen in Maya, linking geometry to descriptions, simulating, caching, applying shaders, rendering and compositing.

Simulating Clothes

Simulating clothes using nCloth in Maya. Mesh with motion capture drives dress & necklace. Cached shirt simulation drives a vest.

VFX for Environment

Simulating nParticles and force fields in Maya for an exterior environment including wind on vegetation, air particles, volumetric lights and water.

Simulating Fluid Injection

Simulating a fluid injection for a shoe sole using nParticles in Maya. Understanding the briefing, developing simulation tactics, caching and rendering.

VFX Workflow

Letting animated characters drive VFX using Maya Nucleus, including flexible cables, molten metal, smoke, sparks, and optical effects.

If you want to know more about rigging and skinning, take a look at these case studies:

Rigging Human Body

Rigging a human body using animator friendly rigging in Maya. Torso, spine, FK/IK, neck, head, pose, fixed elbow, hand, reverse foot, independent pivots.

Rigging Human Head

Rigging a human head with FK/IK minimal joints, creating a user interface, and combining blendShapes to match an expressions sheet.

Skinning Human Body

Skinning a whole human body using Maya Muscle, attaching muscles to joints in Maya, using them as influence objects, and mixing blendShapes.

Skinning Facial Expressions

Using skinning for facial expressions, through quad retopology, minimum Maya joints, importing and combining expressions sculpted in ZBrush.