SIGGRAPH paper: Light Stage
Early in my career, I had the pleasure of working as a Computer Animation Producer in Paul Debevec’s graphics lab at USC’s Institute for Creative Technologies. While there, I had the opportunity to contribute to the design and construction of a profoundly new piece of imaging technology, something we called the Light Stage.
Imagine a geodesic dome covered with 156 programmable LED lights that can accurately reproduce the 360 degree lighting conditions sampled anywhere in the world with a high dynamic range light probe.
The Light Stage was used for a number of Hollywood productions (Spiderman, The Curious Case of Benjamin Button, etc.) and I am happy to boast that it is also widely regarded as the inspiration for the Light Box technique Alfonso Cuarón used for the realistic lighting effects that made Gravity so effective. Here is a nice article about it. If only he used the infrared keying system as well…
- Debevec, P., Wenger, A., Tchou, C., Gardner, A., Waese, J., Hawkins, T.: A Lighting Reproduction Approach to Live-Action Compositing. ACM Trans. Graph. (Proc. ACM SIGGRAPH 2002) 21(3), 547-556 (2002)
We describe a process for compositing a live performance of an actor into a virtual set wherein the actor is consistently illuminated by the virtual environment. The Light Stage used in this work is a two-meter sphere of inward-pointing RGB light emitting diodes focused on the actor, where each light can be set to an arbitrary color and intensity to replicate a real-world or virtual lighting environment. We implement a digital two-camera infrared matting system to composite the actor into the background plate of the environment without affecting the visible-spectrum illumination on the actor. The color reponse of the system is calibrated to produce correct color renditions of the actor as illuminated by the environment. We demonstrate moving-camera composites of actors into real-world environments and virtual sets such that the actor is properly illuminated by the environment into which they are composited.