# Ep.16 — Customizing 01: Hierarchy Structure

https://youtu.be/joFROh0jGag


This document helps you understand the Hierarchy of a BipedPlus Build result, and know **where to attach** customizations (capes, bracelets, etc.).

> **Hierarchy View is the foundation.** Layer View is for organization and visibility — not the basis of rigging.

## 1. Why This Document

BipedPlus quickly creates the structure via Auto Rigging.
But every studio has different naming, props, and additional controllers.
**Understanding the structure reveals where to customize.**

## 2. Four Key Groups After Build

```
Scene
├── Grp_Mod          (Modeling Group)    ← Original mesh
├── Grp_Sys          (System Group)      ← Helpers / INFO that just need to exist in scene
├── Grp_RigModule    (Rig Module Group)  ← Arm/Leg/Head modules + Space
└── Root / Skin tree (Skin Bones)        ← Bones for engine export
```

| Group | Role | What to do |
|-------|------|-----------|
| **Modeling (`Grp_Mod`)** | Character mesh | Place all mesh here |
| **System (`Grp_Sys`)** | Nodes that just need to exist in scene | INFO, helpers, system nodes — animators must not touch |
| **Rig Module (`Grp_RigModule`)** | Arm/leg/head modules + Space | **Main area for customization** |
| **Skin Bones** | Final bones for engine export | Skinning and export reference |

## 3. Two Spaces Inside RigModule

| Group | Meaning | Used by |
|-------|---------|---------|
| **`Grp_Admin_Space`** | BipedPlus internal calculation space | Rarely touched in normal work |
| **`Grp_Custom_Space`** | Spaces aligned to final bone positions | **Where to place capes, bracelets, props** |

**What is a Space?** A group that follows a specific node's position, rotation, and scale.

### Practical Example — Create Space by Selection

1. Select the target bone (e.g., `Skin_Hand`)
2. Run **Edit_Utils → Create Space by Selection**
3. Move the created Space into **`Grp_Custom_Space`**
4. Place bracelets, extra bones, or controllers **under** that Space

## 4. Customization Rules

| Type | Content |
|------|---------|
| ✅ Allowed | Modeling → modeling group, create Space, place custom nodes, add control Ctrl |
| ❌ Do not touch | **INFO node** (stores rigging data), **Admin Space branches** (internal calculation) |

### Why Use Parent Skin Bone Instead of Seg Bone

| | Example | Recommended |
|--|---------|-------------|
| Parent Skin bone | `Skin_Spine1` | **✅** — basis for Space and custom |
| Seg bone | `Skin_Spine1_Seg` | **❌** — may be affected by Stretch scale |

## 5. Checklist

- [ ] Can identify the 4 major groups in Hierarchy View
- [ ] All modeling goes into the modeling group only
- [ ] Customs go under `Grp_Custom_Space` + target bone Space
- [ ] Don't stop at Skin Parent — also create a control Ctrl
- [ ] INFO node is never touched
- [ ] Do not judge structure from Layer view alone