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Photon-sensitive lidar receivers enable range measurements at high probability of detection and low false alarm rate using only 5 - 10 detected photons on average per range measurement. This much-reduced link requirement, compared to photodiodes operating in linear mode, holds the promise of much-reduced system volume, mass, and power consumption, while simultaneously enabling longer standoff and higher measurement rates. We present a commercially-available, Geiger-mode lidar system, called Zion, optimized for rapid collection of dense 3D point clouds using small, economical aircraft. The system mass is under 120 kg and it consumes under 1 kW. Zion has operated at ranges between 800 m and 8,000 m. The area collection rate for data products with density of 100 points per square meter exceeds 300 km2/hr at an aircraft altitude of 1,400 m. The maximum usable measurement rate exceeds 10 million points per second. A significant capability of Zion is the agile geo-referenced scanning system, which can point and scan anywhere within a 40 × 40 degree field of regard. Collection efficiency is optimized by scanning only the desired geographic region of interest (e.g. meandering roads and utility corridors) and even in spite of non-ideal aircraft flight path and attitude. The agile, georeferenced scanning allows the flexibility to maximize oblique imaging of structures or to penetrate dense foliage. The collected points are spread evenly across the imaged area, which reduces image artifacts and simplifies processing. This system has flown over 50 flights, and is currently operational.
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