Since ancient times, cartographers have strived to make maps that accurately reflect the world. A central challenge of the art is projecting the Earth, which is curved, onto flat paper and screens. Many methods of projection have been proposed over the centuries, but to date no universally good answer has been found: every choice is always a tradeoff tuned for its intended use. Because new services like Google Maps and applications like VR video seek to provide accurate and meaningful information about our curved, 3D world on a 2D screen, this challenge persists even today.

While traditional cartography techniques must address the basic challenge of how to represent the world in 2D, video streaming also faces a new constraint that early mapmakers didn’t have: making efficient use of bandwidth. Streaming high quality video pushes the limits of network bandwidth, particularly for mobile networks. And when considering VR video, the bandwidth demands are vastly increased since it must represent imagery from a full sphere rather than just a small window onto the world. Stereo video roughly doubles the data yet again. Therefore making the most of available bandwidth is a top concern.

Now, in a joint effort between YouTube and Daydream , we're adding new ways to make 360 and VR videos look even more realistic in a bandwidth-constrained world. This post delves into how these techniques work thanks to Equi-Angular Cubemaps (EACs). To benefit from them, consider putting your content on YouTube. EACs are likely to be useful in many other contexts as well, so we look forward to seeing what can be done with them.