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How to add bones to the spine in an animation?

When it comes to animation, adding bones to the structure of a model is crucial to facilitate its movement. Here we will explain how to add bones to a character's spine using animation software.

First step: Preparing the workspace

To begin with, it is optimal to erase any objects used to explain previous concepts, ensuring a clean working area. One of the key tools in this process is the use of the perspective view, as it provides a full angle of the scene, which is essential for accurate bone placement.

How to add and position the bones?

1. Creating the first bone:

   • Add the bone directly to the center of the scene.
   • Adjust its position so that it controls the hip, bringing the bone from the front view to its respective place.

2. Bone naming:

   • Use clear labels for each bone, such as:
     • Hip_deformer: Assign this name to the bone that will control the hip.
     • Chest_deformer: Duplicate the hip bone and move it to the chest area.
     • Deformer_vertebra1, Deformer_vertebra2, etc..: Creates a chain of bones to represent the vertebrae.

Bone structure configuration

• The chain of vertebrae:
  • Although the human body has approximately thirty vertebrae, for basic animation purposes, only three can be used. The structure would look something like:
    • Vertebra1 → Vertebra2 → Vertebra3.
  • These vertebrae will control different parts of the spine and their movement will influence the character's torso.

How to connect the bones using neutrals and controls?

• Neutrals and controls:
  • Neutrals define the origin of the controls for the bones. Name them using a prefix such as N_TR followed by the name of the area they will control (for example, N_TR_hip).
  • Controls are essential for motion manipulation in animation and are usually named with CTR_L. An example would be CTR_L_hip.

# Pseudocode for basic bone structure renderinghip_bone = create_bone(center=True)label(hip_bone, "Hip_deformer")
chest_bone = duplicate_bone(hip_bone)label(chest_bone, "Chest_deformer")position(chest_bone, "chest")
 # vertebrae creationfor i in range(1, 4):
    vertebra = duplicate_bone(hip_bone) label(vertebra, f "vertebra_deformer{i}") position(vertebra, f "vertebra_position{i}").

How to ensure proper mobility?

When completing the structure of bones and neutrals, create control constraints (constrains) for the controls to move the associated bones. This will ensure that, when modifying the hip control, the character's hip will also move.

Motivation for further learning

Animation is a constantly evolving art, and each technique learned opens up a world of creative possibilities. Experiment with these tools and discover new ways to bring your characters to life. Keep exploring and let this knowledge awaken the animator in you.