Armature 101

Table of Contents

What is armature

An “armature” is a type of object used for rigging. A rig is the controls and strings that move a marionette (puppet). Armature object borrows many ideas from real-world skeletons.¹

What is bone

Bones are the base elements of armatures². There are two types of bones:

1. Deforming Bones: are deform/transform vertices which associated.
2. Control Bones: are control other bones or objects

They have three elements:
1. The “start joint” named root or head.
2. The “body” itself.
3. And the “end joint” named tip or tail.

Modes & Pie Menu

Object mode: Edit transform and similar things of objects
Edit mode: Edit armature shape
Pose mode: An armature-only mode, dedicated to posing.

Once an armature is skinned by the needed object(s), you need a way to configure the armature into positions known as poses. Basically, by transforming the bones, you deform or transform the skinned object(s). However, you will notice that you cannot do this in Edit Mode – remember that Edit Mode is used to edit the default, base, or “rest” position of an armature. You may also notice that you cannot use Object Mode either, as here you can only transform whole objects. ³

Edit>Preferences…>Keymap>Tab for pie menu

When we press tab key, we will see the pie menu:

Basic operations

Right click menu

right click in edit mode is give this menu to us

Subdivide: Divide into n pieces an existing bone
Duplicate: Create an copy of existing bone
Extrude: Extrude a new bone from tip or root of a bone.
Fill Between Joints: Create a new bone between selected two points (tip or root)

Mirror: Mirror around selected transform pivot point
Snap: Snapping bones or cursor
Symmetrize: will mirror the selected bones along the X axis based on Blender’s bone naming convention for symmetrical armatures, either from left to right or right to left, depending on the selection. ⁴
Switch Direction: inverts bone
Names: Auto naming of bones by naming convention

with mirror you just create a copy of bones BUT in symmetrize you create a connection between left and right bones.

Parent
- Make
  - Keep Offset: Add a parent to the bone but keep current position.
  - Connected: Add a parent to the bone and move it to the tip of the parent.
- Clear
  - Clear Parent: Clear parent of bone. Child-parent relationship is ending
  - Disconnect Bone: Discconect bone from its parents tip but child-parent relationship is remaining
Split: Disconnect bone from its parent and childs.
Separate Bones: Create a new armature object from selected bones

Dissolve Selected Bones: Dissolve will remove the bone and fill in the surrounding bones.
Delete Selected Bones: If you delete a bone in a chain, its child(ren) will be automatically re-parented to its own parent, but not connected, to avoid deforming the whole armature. ⁵

Before – Dissolve – Delete

Armature Menu

We can find a few more operator on this menu:

Bone Roll: In Edit Mode, you can control the bone roll (i.e. the rotation around the Y axis of the bone).
However, after editing the armature, or when using Euler Rotation, you may want to set the bone roll. 6
Extrude to Cursor: Create new bone between last selected point and mouse cursor
Bone Collection: We can assing or moves the bones to new collections.
- move: remove from current collection and add to selected one
- assing: add to selected one

Bone settings: ⁷
- Display Wire: Always display the bone as wireframe.
- Deform: Toggle deform
- Multiply Vertex Group by Envelope: These settings control how the bone influences its geometry, along with the bones’ joints radius. This will be detailed in the skinning part.
- Inherit Rotation: The bone automatically rotates together with its parent in Pose Mode. For more details, see the relations page.
- Lock: This will prevent all editing of the bone in Edit Mode; see bone locking.

Viewport Display

Bone Color: We can change the color of bone in edit and pose mode
Bone Shape: We can use a new mesh instead of default mesh.

Object to bone

We following these steps for parenting an object to bone:

Disable Lock Object Mode
Select Mesh -> Select Armature -> Pose mode
Ctrl+P -> Bone

Post&Rest position

Yes, it’s also useful when you edit any mesh associated with the armature. You can set rest position to see that anything new you might add gets added in the right place.

For example: you have a human character that you have posed, you then want to add a hat. So you put the armature into rest position, then you add the hat at the correct location to the main mesh, then you rig the hat to the armature, then you return to pose position and the hat will be in the right place. If you place the hat on the head in pose position and the head has been moved, your hat might then not be on the head when you try parenting the hat to the armature and re-posing the character. Not a brilliant example, but you get the point hopefully.

I suggest you search out Nathan Vegdahl’s “Humane Rigging” tutorials if you re rigging characters – they are superb. If you are rigging mechanics things, talk to me… or one or two others here who do a lot of mechanical “hard body” rigging. It would be useful to know what you are working on so we can help better.

Cheers, Clock-down-under.

PS. Sorry if this message is upside down, I am in Australia rather than my home just now…

https://blenderartists.org/t/what-use-is-the-rest-position-in-pose-mode/678346/3

Clear Transform: Clear rotation, location and scale of selected bones
Apply (CTRL+A):
- Pose as Rest Pose: Conversely, you may define the current pose as the new rest pose
- Pose Selected as Rest Pose: Same as Pose as Rest Pose but only applies to selected bones.
- Visual Transform to Pose: Applies the position of the bone after Constraints; allowing the constraints to be deleted and the bones will remain in their constrained positions.
- Assign Custom Property Values as Default: Assign the current values of custom properties as their defaults, for use as part of the rest pose state in NLA track mixing. ⁹

Pose Mode – Viewport Display

Bone shapes

Octahedral: This is the default visualization, well suited for most of editing tasks
Stick: This is the simplest and most non-intrusive visualization.
B-Bone: This visualization shows the curves of “smooth” multi-segmented bones; see the Bendy Bones for details.
Envelope: This visualization materializes the bone deformation influence. More on this in the bone page.
Wire: This simplest visualization shows the curves of “smooth” multi-segmented bones.¹⁰

In Front: When enabled, the bones of the armature will always be shown on top of the solid objects
Relations: Whether the Relationship Lines overlay should be drawn from each parent’s tail or head. The lines are always drawn towards the childrens’ heads.

Bendy Bones

Inherit

Inherit rotation

Inherit scale

Usefull add ons

Copy Attiributes Menu: This add-on extends the Copy Objects Ctrl-C hotkey to include many extra copy types. ¹¹
Bone Selection Sets: Selection Sets are a feature that allows the definition of sets of bones for easy selection while animating. ¹²

Inverse Kinematic

Select Target(ctrl) bone, select Bone_2, SHIFT+I