New algorithm can supposedly stabalize herky-jerky 360
degree videos.
Last week,
President Barack Obama dipped his toes into the world of virtual reality.
He starred in a short film during a recent
trip to Yosemite
National Park that was shot with high-end cameras that capture video in full
360 degrees. Viewers wearing virtual reality headsets could crane their necks
to gawk at Yosemite’s majestic granite cliffs and tranquil meadows as if they
had tagged along with the president.
It was the
next best thing to being there.
President
Obama’s trip was a showcase of what is possible by filming video in 360
degrees. But it’s also a reminder of how much work remains to be done before
tourists are able to film their own vacations like that of President Obama by a
professional VR studio for Facebook’s Oculus Rift virtual reality business.
Facebook FB 0.15% has been a big proponent of 360-degree video (in addition
to regular, old video in general), and over the past year
has added several data
center and video
processing technologies
so that it can more efficiently show 360 degree videos to users without
annoying delays.
By improving the technology for consumers to both watch
and create videos in 360 degrees, the social network hopes to benefit by
keeping its over 1 billion users more engaged and active. As of now, however,
most amateur 360-degree video being shot is “super shaky and not so watchable,”
said Johannes Kopf, a research scientist in Facebook’s computational photography
research group.
Watching one
of these shaky 360 videos using a headset can be disorienting and can even
cause people with sensitive stomachs to feel queasy, Kopf explained. To deal
with these wobbly videos, Facebook built a new algorithm that Kopf said can
automatically improve amateur videos by removing some of the unwanted
unsteadiness that is typical when non-professionals film using a camera in
their untrained hands.
The algorithm is part of what’s known as electronic image stabilization,
a type of video processing that can help smooth the jerkiness in videos even
when filmed in an unsteady environment, like from a dirt bike cruising down a
bumpy trail.
Currently, many different automatic video stabilization
tools are available for standard, flat video, but there are not many designed
for 360 video. Companies like VideoStitch and Mettle as well
as academic researchers have all been
working on ways to smooth bumpy 360 videos, but the technology is not yet
widespread.
Unlike some
video technology companies, Facebook does not want to sell video-processing
software to consumers. Instead, it wants to bundle its homegrown 360-degree
video smoothing technology into its social networking service so that when
users upload videos, the stabilization technology works automatically behind
the scenes to remove some of the jittery imagery, Kopf explained.
Facebook’s video stabilization tool involves slicing a
video into chunks, or key frames. The engineers used an existing image tracking technology to pinpoint specific objects within a
video, which allows them to keep track of those objects in the film over time.
So in the
case of a 360-degree video of a yellow ball filmed with shaky hands, Kopf said,
Facebook can lock onto that ball and keep track of its original position.
As the film
progresses and the ball starts moving away from its center position of the
image because of poor camera work, the algorithm can essentially rotate each
key frame so that the ball magically appears in the same spot in every frame.
Once the key frames are rotated, the algorithm can then re-orient all the other
video frames in relation to the stabilized key frames, which helps if there
happens to be multiple balls in the scene.
“It’s like a
balance, you can’t smooth them out all at once,” said Kopf. “Different parts of
the scene might be moving in slightly different ways, and by having more
localized information you can smooth them out as well.”
The
algorithm can also slightly deform each frame as well, so that in the case of
an extreme wobbles the actual frame gets a little tweaked to conform to where
the ball should be. Once stabilized, the film should appear less amateurish
than before and less nauseating of an experience.
Kopf and his
team started working on the technology in January and is still testing and
improving it. Facebook hasn’t decided when to actually start rolling it out to
all of its users.
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