Light-field photography is truly impressive, with almost limitless depth of focus that opens up whole new options for professional photographers and specialists. And now, with the emergence of affordable cameras, amateurs are getting in on the action, too. Not only does the technology allow users to change the point of focus in an image even after the picture has been taken, it can also be used to take three-dimensional photographs. However, when it comes to videos, light-field technology is much less widely used, particularly since the necessary hardware is virtually unavailable. Among the few with access to the necessary camera equipment is Saarland University. Researchers from the university are at CEBIT 2018 to showcase videos shot on their system and present the details for the first time.
"No image information is lost any more," explains Thorsten Herfet, Professor of telecommunications at Saarland University, explaining the effect of the camera system. "If, for example, you film a cyclist who is obscured by a shrub during recording and is therefore only partially visible, you can completely eliminate the shrub during post-processing," continues Herfet, who developed the system with his colleagues Tobias Lange and Frank Wassmuth over the last twelve months.
For the light field videos to work, it is crucial that the same scene is shot from multiple angles. To do just that, the computer scientists have arranged 64 cameras in an array which can be adjusted in terms of its area. Each camera has a resolution of 1920x1200 pixels, 8-bit color depth and can shoot up to 40 frames per second. "We can control each camera independently of the others on the timeline and thus selectively replace individual image areas with earlier or later images," explains Herfet. "This enables us to shoot movement in a completely new way. You could say we're breaking into the fifth dimension." While the video is being shot, image data from each camera is processed by its own mini-PC, which is no bigger than a lunchbox. "The fast hard disks of these small office PCs are particularly important, as each camera sends 270 megabytes of data per second during recording," explains Lange, who is a PhD student working under Professor Herfet. The 16 mini-computers are combined in a one-meter-high case that Lange developed and produced using a 3D printer. From there, the image data is sent to the central storage unit, which can hold more than 50 terabytes.