![]() We do this by transforming the top 25 percent of the equirectangular video to one cube face and the bottom 25 percent to another cube face. As an example, a 10-minute 360 video has 300 billion pixels that have to be mapped and stretched all over the cube. In order to implement our transformation from equirectangular layout to cube map, we created a custom video filter that uses multiple-point projection on every equirectangular pixel to calculate the appropriate value for every cube map pixel. The shark images used to demonstrate the concept are taken from a 360 video from Discovery, one of the first publishers to share 360 video on Facebook: You can see the process for creating a cube map in the slide show below. Each face is mapped only on the corresponding face of the cube. There are no poles as in equirectangular projection, which contains redundant information. Cube maps’ pixels are well-distributed - each face is equally important.And that’s why it encodes better than with bended motions in equirectangular. This is important because video codecs assume motion vectors as straight lines. So each face looks exactly as if you were looking at the object head-on with a perspective camera, which warps or transforms an object and its surrounding area. Cube maps don’t have geometry distortion within the faces.There are a few benefits of using cube maps for videos: Cube maps have been used in computer graphics for a long time, mostly to create skyboxes (six-sided cubes that are drawn behind all graphics) and reflections. Cube map solutionĬube map projection is a combination of six faces of the cube. We found our solution to this problem by remapping equirectangular projection layouts to cube maps. In 360 video, instead of a warped landmass, there are either same-color pixels nearby or pixels that are indistinguishable at the render time, like in this image: How you display the map affects how much extra Antarctica there is in the image. Antarctica is really a circular landmass, not a drawn-out linear one. Think of it in terms of a map of the globe. The problem is that this layout can contain redundant information at either end. The first thing we wanted to tackle was a drawback of the traditional layout used for 360 videos, called an equirectangular layout. ![]() Here’s how we approached building this experience. From mammoth incoming raw file sizes to warped, stitched-together imagery, 360 video is a generous playground for an engineer looking to solve a broad set of challenges. It’s an immersive addition to the ways that people can share and connect on Facebook, but it was a launch with an abundance of technical challenges to overcome. It’s like turning your head to look around a room - you control the perspective. With 360 video, you can choose which angle you want to view the video from. We were excited to roll out 360 video for News Feed recently. ![]()
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