2160p refers to a Progressive high definition video signal or display with 2160 horizontal lines and an Aspect ratio of 16:9 (1.78:1). It's also often called either QuadHD in reference to having four times as many Pixels as the highest standard HDTV Resolution (1920x1080). It may also be referred to as 4K2K (or 4K for short) in reference to having approximately 4000 vertical lines and 2000 horizontal lines.
While there have been 2160p displays and projectors developed by several companies, so far the lack of consumer video with a matching Native Resolution has kept the technology from being adopted in consumer electronics.
Getting Started With HDTV
Afterdawn HDTV Buyer's Guide
Introduction To Next-Generation Multimedia - HDTV Technology
Introduction To Next-Generation Multimedia - High Definition Video and Audio
Digital Video Fundamentals - Resolution and Aspect Ratio
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