Pixel Mapping for Large-Scale Facade Displays
Pixel mapping is the technical process that translates visual content (images, video, generative patterns) into individual control commands for thousands of LED nodes distributed across a building's irregular exterior. Unlike a conventional display where pixels sit on a uniform grid, facade pixels follow the building's architecture — with gaps for windows, varying spacing between floors, and three-dimensional surface geometry. This guide covers DMX addressing strategies, Art-Net/sACN network architecture, content creation workflows, and the rendering pipeline that connects a media facade design to its physical LED installation.
DMX addressing architecture
Every controllable LED node requires a unique DMX address. An RGBW pixel uses 4 DMX channels (Red, Green, Blue, White). A single DMX512 universe provides 512 channels — enough for 128 RGBW pixels. As facade pixel counts increase, the number of required universes grows rapidly:
| Facade Size | Pixel Count | DMX Universes | Distribution |
|---|---|---|---|
| Small retail (500 m²) | 500-1,000 | 4-8 | Direct DMX cabling |
| Medium commercial (2,000 m²) | 2,000-5,000 | 16-40 | Art-Net over Ethernet |
| Large tower (10,000+ m²) | 10,000-30,000 | 80-240 | sACN over fiber backbone |
| Landmark (Burj Khalifa scale) | 70,000+ | 1,500+ | sACN + fiber + floor distribution |
Content creation workflow
Content must be created specifically for the facade's pixel layout — standard video files will not render correctly. The workflow is: (1) create a pixel map document showing every node's XY coordinate, (2) render content to match the map's resolution and aspect ratio, (3) apply any geometric correction for building curvature or non-planar surfaces, and (4) output the corrected content to the media server for real-time playback.
Art-Net vs sACN
For multi-universe distribution beyond a single DMX cable, two protocols dominate:
- Art-Net — transmitted over standard Ethernet (Cat6). Widely supported by media servers and lighting controllers. Supports up to 32,768 universes. Best for systems under 10,000 pixels on a single network segment.
- sACN (E1.31) — ANSI standard streaming ACN. Uses multicast for efficient bandwidth management. Better suited for large installations where network traffic management is critical.