Structured light 3D imaging enabled at extreme speeds and challenging scenarios using single-photon cameras and digital micro-mirror devices.
Structured light 3D imaging systems have inherent tradeoffs balancing the precision of the 3D scan against its acquisition time. For instance, certain structured light techniques achieve high depth resolution by projecting multiple patterns but require long acquisition times. At the other extreme, some techniques project a single pattern, facilitating high speed but result in loss of detail. Such tradeoffs are exacerbated when operating in challenging regimes with low signal-to-noise ratios arising from either low-albedo objects, dynamic scenes, or strong ambient illumination.
In this work, we leverage Single Photon Avalanche Diode (SPAD) arrays, an emerging class of single-photon imaging sensors, to enable 3D scanning at high-frame rates and low-light levels. This technique, called Single-Photon Structured Light, works by sensing binary images that indicates the presence or absence of photon arrivals during each exposure. We use the SPAD array in conjunction with a high-speed binary projector, with both devices operated at speeds as high as 20 kHz. The acquired binary images are heavily influenced by photon noise and are easily corrupted by ambient sources of light. To address this, we develop novel temporal sequences using error correction codes that are designed to be robust to short-range effects like projector and camera defocus.
Our lab prototype is capable of 3D imaging in challenging scenarios involving objects with extremely low albedo or undergoing fast motion, as well as scenes under strong ambient illumination.
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