3D Animation Rigging: Concepts and Techniques

• University of Perpetual Help System DALTA presents Lesson 1: Overview of Modelling and Rigging

What is Rigging?

• In skeletal animation, rigging is a technique where a network of interconnected digital bones is applied to indicate a 3D character model.
• Rigging involves building a 3D model's skeleton and controls the bone structure as a puppet for animation.
• Brian Green of Pixar describes rigging as adding control to a digital model.
• Rigging can be applied to almost anything, including vehicles, characters, and props, by adding bones.

What is Rigging in 3D Animation?

• Rigging is commonly used in animated characters for video games and animations, improving animation process efficiency.
• Any 3D object can be controlled and changed by wiring it with skeletal bones.
• Rigging is essential in animating characters in the entertainment business.
• Characters are typically rigged before animation because a character model cannot move around without a rig.

The Importance and Purpose of Rigging in Animation

• Digital animation software enables modification of a bone's placement, rotation, and scale during rigging.
• 3D rigging creates a 3D model’s skeleton, with bones having specific capabilities and limitations, similar to a real skeleton.

Why Correct Rigging is Vital in Animation Production?

• Correct Rigging allows for believable movement.
• Correct rigging aims to make movement believable and organic. Figures and objects need move as viewers expect.
• Correct rigging enhances animator efficiency.
• Ergonomic rigs allow animators to focus, for faster animation and reduces the time spent tweaking crucial for business.
• Proper rigging includes the use of:
  • Correct skeletal system
  • Inverse kinematics
  • Simplified limb animation
  • Speeding up long-advanced animations.
• Rigging allows for animation consistency
• A pelleted character ensures consistent movement quality across animators and continuity across games or films.
• A standardized rig allows animation retargeting where it is beneficial for running multiple characters in the same game.
• It enables complex interactions involving objects, and preventing characters from clipping through solid objects or reducing immersion.
• It impacts the visual aesthetic with animations by providing transitions and maintaining character sizes. Ensures natural and believable looking characters across games or film.
• It allows a multitude of facial expressions, where bone structures and morph targets replicate human muscle movements that enhances narrative in film and games and allows for realistic characters.
• Reduces Costs in the Long Run
• Early rigging in a project can lead to long-term cost savings, saving animators both time and money.
• A strong rig can accommodate multiple animations without alterations, while standardizing rigging practices optimizes production processes and allocating resources better.
• Improves Real-Time Performance by:
  • Ensuring smooth performance without over-complexity
  • Requires minimal detail and functionality
  • Supports LOD systems
  • Optimizes scenes based on screen distance
  • Frame rates and maintaining visual and gameplay quality
• Supports New Technologies
• Virtual Reality (VR) and Augmented Reality (AR) technologies need high-fidelity rigging for immersive and believable interactions, which can require translating human movements into digital characters.

How Does Rigging Work?

• Rigging is integral to the animation process, and starts with character design.
• It involves building a skeleton structure with a set of bones within a 3D model, which can include backbones, a spine, and head bones.
• Animators create animations by capturing various bone features along a timeline using keyframing.
• The duration of the rigging setup can vary that takes anywhere from a few hours or days depending on the complexity of the rigs..

Which is the Best 3D Rigging Software Program?

• There are numerous 3D rigging software programs that come with their own features and options.
• Photoshop
• ZBrush
• Maya
• Many 3D rigging artists use multiple programs:
  • Maya
  • Blender
  • 3Ds Max
  • Modo
  • ZBrush
  • Cinema 4D
  • Houdini

How to Properly Rig Your Characters for Animation

• Once the character is modeled, it gets prepared for animation using a process called rigging, which is a combination of adding a skeleton and controls to the model.
• A well-built skeleton will allow for the character to be quickly and easily manipulated to attain any pose.
• The rigger is part animator, part programmer, and part interface designer.
• Rigger understands the needs of animators.
• The perfect Rigger allows animators to have control over the character and automatically managing the parts of a character.

Hierarchies and Character Animation

• 3D Software

• Create a hierarchy of character information, resembling a tree structure

• Hierarchy connects bones, forming branches similar to nested directories on a computer

• After animation, the hierarchy is set up

• The Body is built from the Hips or Pelvis:

  • Pelvis close to the center of gravity
  • Is the center of weight distribution for the entire body
  • Supports the spine and the weight of the upper body passing those forces down through the legs to the ground
  • All motions in a character start from the hips

Skeletons

• A single-skin character is deformed using a skeleton of bones and joints, similar to the human skeleton.
• In 3D software, bones act as helper objects, guiding the deformation utility.
  • Virtual bones assist the skeleton to deform a mesh
  • Virtual bones may not match a real skeleton exactly

Skeletons: Animated

• The bones built within the mesh will assemble into a hierarchy which then becomes animated.
• Once the skeleton is assembled, there are two strategies:
  • Forward Kinematics
  • Inverse Kinematics.

Forward Kinematics

• Forward kinematics (FK) is the primary manipulation method for skeletons that is rotation based where you position the joints by rotating them.
• It provides a good simulation of reality.
• If a hand needs to be placed on a coffee cup, first rotate:
• Shoulder
• Elbow, then the hand
• Wrist and fingers
• From hierarchy, the rotation brings the hand closer.
• FK cannot simply pick the hand and place it on the cup, as the wrist is left behind.

Inverse Kinematics

• Inverse kinematics (IK) works the opposite way; it's translation based instead of rotation based.
• Inverse kinematics allows for placing the character's hand on the coffee cup, and the rest of the arm automatically follows.
• Complex because the software must solve the rotations for all of the joints in the arm.

Parts of and IK Chain

• An IK chain has joints manipulated by an object called an effector. The first joint is known as the root of the chain for data that helps position the chain that may not be the entire skeleton.
• Moving the root of the IK chain moves everything in the hierarchy. The tip of the last joint is the effector.
• The effector controls the IK chain, allowing the software to position the chain so that it runs between the root to the effector with bones connected by joints.

Manipulating A Chain

• Use the effector to manipulate the IK chain where the joints of the chain will rotate accordingly.
• Easily pose and animate a character by focusing on a single effector rather than the rotations of many joints.
• Software will keep the joints at a fixed length, so the fully extended chain simply aims itself at the effector.
• Software can allow joints to stretch for a cartoon squashing and stretching motion.
• Move the chain by translating the root where the IK effector is outside of this hierarchy, then the chain locks onto the world.
• The effector connects to another object through a hierarchy; for instance, a character riding a bike, with effectors keeps the arms locked to the handlebars.

Joint Limits

• To prevent the incorrect bending of joints there is software with exactly set limits for that specific joint and axis-by-axis basis:
  • Hinged
  • Socket

Explore the core principles of rigging in 3D animation, including its purpose, importance, and benefits. This includes the role of inverse kinematics (IK) and forward kinematics in creating believable character movements. The ideal balance a character rigger strives for in a character.