The Bullet Time effect became known to the general public thanks to the saga The Matrix, but it is not a discovery or an invention of the film’s creators, although they did help popularize and globalize it. This is a high cost multi-camera effect as it requires a large number of cameras.
The good news is that costs have come down, and what was once only within the reach of a Hollywood production is now possible using low-cost hardware. Eric Paré and his team are experts in creating the Bullet Time effect, and decided to push it to the limit with a special configuration of 15 Pi Cams and Raspberry Pi.
Who is Eric Paré?
Eric Paré is a visual artist from Canada who does Light Painting, and plays with the concepts of time, light and space with his photography that explores the delicate beauty of women and their bodies, from a hypnotic handle that pairs illumination and movement. He has held various workshops and conferences in cities such as Dubai, San Francisco, Mexico City, New York and Toronto.
He developed too different camera systems software to create bullet time, slow motion and light painting effects.
The Raspberry Pi is a series of low-cost small board computers, single board computers or single board computers (SBC) developed in the UK by the Raspberry Pi Foundation, with the aim of putting the power of computing and digital creation into the hands of people around the world.
The official camera for the Raspberry Pi averages 30 euros. With 8 megapixel resolution and an ultra-compact format, DIY enthusiasts have used it for all kinds of projects. However, the feeling is that it falls short in specific cases. This led the Raspberry Foundation to launch its upgrade, the 12.3 megapixel Pi Cam HQ with C-mount, which allows us to experiment with different objectives.
So, what can we do? How does Bullet Time sound?
Obviously, professionals adopt much more advanced settings with DSLR cameras and complex synchronization systems, but Eric Paré decided to follow this particular low-cost route, and after multiple adjustments, we must admit that the final result is very good:
How the did it
Eric and his team started working on a Pi Cam version of their multi-camera system several months ago, although at first it had nothing to do with Bullet Time, but with photogrammetry.
The reduced size of the cameras became an advantage, as Eric was able to achieve a much higher than normal density in these structures.
But the first version suffered calibration problems due to a small detail: The lens of the Pi Cam is mounted on the PCB with a kind of thermal paste (which in the video looks like foam), which destroys any attempt at precision extended to fifteen modules.
The solution was to modify each of the lenses to eliminate the paste and obtain more solid joints.
The general configuration is based on 15 normal Pi Cams, 15 Raspberry Pi 3B+, and continuous light. There are no custom electronics here beyond the mod needed in the lenses, and a small PCB to send a signal to the speedlite. Each Pi is connected to a laptop via Ethernet, and the trigger is a simple Bluetooth unit used in PowerPoint. Needless to say, Eric doesn’t plan to replace his professional equipment with this, but it opens up a wide range of possibilities, and it’s also compatible with the new HQ modules.