Figure 1: Imagine trying to acquire live video (30fps) of structured-light patterns as they are being projected onto a compact fluorescent bulb that has already been turned on (rated 1600 Lumens), or onto a face in bright sunlight (80 kLux)-with a 5-Lumen projector. One of our two prototypes, shown in (a), achieves this with an off-the-shelf laser projector and a CMOS camera with an ordinary lens. We then used it to capture the video frames in (b) and (c). We also show how to use our prototype to generate a live video feed from the projector's-rather than the camera's-point of view, shown in (d).
AbstractProgrammable coding of light between a source and a sensor has led to several important results in computational illumination, imaging and display. Little is known, however, about how to utilize energy most effectively, especially for applications in live imaging. In this paper, we derive a novel framework to maximize energy efficiency by "homogeneous matrix factorization" that respects the physical constraints of many coding mechanisms (DMDs/LCDs, lasers, etc.). We demonstrate energy-efficient imaging using two prototypes based on DMD and laser illumination. For our DMDbased prototype, we use fast local optimization to derive codes that yield brighter images with fewer artifacts in many transport probing tasks. Our second prototype uses a novel combination of a lowpower laser projector and a rolling shutter camera. We use this prototype to demonstrate never-seen-before capabilities such as (1) capturing live structured-light video of very bright scenes-even a light bulb that has been turned on; (2) capturing epipolar-only and indirect-only live video with optimal energy efficiency; (3) using a low-power projector to reconstruct 3D objects in challenging conditions such as strong indirect light, strong ambient light, and smoke; and (4) recording live video from a projector's-rather than the camera's-point of view.