Canadian photographer Eric Paré has built a bullet-time rig using 15 Raspberry Pi cameras synchronised to record pictures at exactly the same moment from different angles. The cameras then create a series of images that show the subject, usually someone jumping in the air it seems, from multiple viewpoints. These images can then be put together as a video to show the person frozen in mid-air as the camera appears to pan around them. The technique, made popular by the fight scenes in the movie The Matrix, requires that the cameras used are all pointing at exactly the same spot and that the shutters are tripped either at the same moment or in sequence.
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Eric usually uses a collection of EOS DSLRs for his bullet-time videos but thought it would be interesting to use the tiny Raspberry Pi cameras as the lenses can be placed much closer together to create smoother motion in the final video. To do this he mounted 15 cameras on an aluminium rail and synchronised them using a single dashboard that could also control the settings of each camera.
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Problems arose due to the wide angle lens of the Raspberry Pi camera and because the cameras are mounted on their PCB using a gum glue that doesn’t hold them in a specific position. This meant that while the boards were all facing the right way the cameras were not, and the footage produced was jerky. Eric solved this issue by remounting all the camera units directly to the boards using a thin adhesive.
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Each camera in the rig was connected to the laptop via an Ethernet cable to a switch and Eric triggered the set-up using a Bluetooth presenter controller. He says he didn’t need to make any custom electronics for the rig when shooting with continuous lighting, but he did make a new control board to fit in the rig when he wanted to use flash.
For this experiment Eric used the Pi 3B+ with version 2 of the Raspberry Pi camera module. He says the same set-up would also work with the newer High Quality Pi camera with its 12MP sensor and interchangeable C-Mount lens system.
See Eric’s website for more of his work.
Articles: Digital Photography Review (dpreview.com)