The landscape of stage lighting has shifted dramatically toward multi-emitter fixtures. Modern rigs are packed with LED pixel bars (e.g. 16-cell battons), moving head wash lights with concentric LED rings and center spot emitters, dual-tilt moving heads, and high-density strobe panels.

On traditional lighting consoles, accommodating multi-cell fixtures is notoriously frustrating: operators are forced to either patch 16 separate single-channel fixtures (cluttering the patch list and losing global pan/tilt control) or treat the fixture as a single coarse lamp (losing pixel mapping).

Unilighter solves this with a native **Multi-Head Architecture** that treats complex multi-emitter fixtures as unified, intelligent single-device containers.

![Multi-Head Fixture Channel Mapping - Master Dimmer on Shared channel alongside independent color emitters assigned to Head 0 and Head 1](https://unilighter.cc/info/docs/multi-head/multi_head_device_af87d367.png)

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## 🧱 The Single-Container Model

When you patch a 16-cell pixel bar or a ring-wash moving head in Unilighter:
- You patch **exactly one device** in your patch list.
- Unilighter allocates the entire continuous DMX footprint automatically.
- All internal sub-emitters (heads) remain individually controllable while sharing master fixture attributes.

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## 🔀 `SHARED_HEAD` vs. Independent Emitters

Unilighter partitions fixture channels into two distinct scopes:

### 1. The Shared Head (`SHARED_HEAD = -1`)
Channels assigned to the shared scope govern global physical attributes of the fixture housing:
- **Master Dimmer & Strobe**: Controls total luminous output across all heads simultaneously.
- **Pan / Tilt & Pan/Tilt Fine**: Physical mechanical motor orientation.
- **Optics & Mechanics**: Global Zoom, Focus, Frost filter, and Gobo wheels.
- **Built-In FX & Macros**: Internal fixture chase macros and speed controls.

### 2. Independent Heads (`H0, H1, ... Hn-1`)
Channels assigned to specific head indices represent localized, independent emitters:
- **Cell Colors**: Independent $R, G, B, W$ channels for each individual lens or pixel diode.
- **Cell Dimmers**: Dedicated intensity channels per pixel (if supported by fixture mode).
- **Secondary Pan/Tilt**: Independent tilt angles on dual-head moving bars.

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## 💡 Intelligent Dimmer Inheritance & Multiplied Output

A major advantage of Unilighter's multi-head engine is its hierarchical intensity resolution:

$$\text{Effective Intensity} = \text{Master Shared Dimmer} \times \text{Head Cell Dimmer}$$

- **Blackout with One Fader**: Bringing down the master fixture dimmer gracefully fades out all 16 heads at once, without clearing or altering individual pixel color patterns.
- **Fallback Dimming**: If a multi-head fixture profile does not have per-pixel dimmers, Unilighter automatically maps the master dimmer across all heads.
- **Per-Head Color Calibration**: Each individual head can have independent color correction applied in [Color Engine](https://unilighter.cc/info/for-ai/docs/colors.md), ensuring uniform whites across every cell of a pixel batton.

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## 🏷️ Tagging & Targeting Multi-Head Fixtures

Unilighter's [Fixture Tags](https://unilighter.cc/info/for-ai/docs/tags.md) and parameter selectors seamlessly address both global fixtures and localized heads:

- **Targeting All Heads**: Selecting `#StageBars` in a color picker sets all pixels on all patched bars simultaneously.
- **Targeting Shared Parameters**: In [Keyframe Animations](https://unilighter.cc/info/for-ai/docs/animations.md) or [Node Graphs](https://unilighter.cc/info/for-ai/docs/node-graphs.md), binding to `pan (Shared)` moves the physical bar while leaving pixel color chases untouched.
- **Targeting Specific Heads**: You can isolate sub-emitters (e.g. `#StageBars.h0` for the first pixel of every bar, or the outer LED ring of a wash head) to generate intricate geometric chases.

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## 🌐 2D & 3D Stage Visualizer Integration

In Unilighter's built-in 2D Stage Layout and 3D Visualizer, multi-head fixtures are rendered with accurate physical spacing:
- Each pixel cell emits light from its true spatial coordinate along the fixture bar.
- When the fixture moves in Pan or Tilt, all child heads rotate cohesively in 3D space.

Read more in the **[Device Patch & Universe Setup Manual](https://unilighter.cc/info/for-ai/docs/device-patch.md)** and the **[Fixture Profile Editor](https://unilighter.cc/info/for-ai/docs/fixture-editor.md)**.