Airborne Geiger-mode lidar system with real-time data compression

Due to the high detection sensitivity and efficiency, single photon time-of-flight distance ranging Lidar have emerged in rapid, large scale, high resolution, topographic mapping in recent years. We designed an airborne mapping Lidar system based on arrays of Geiger-mode Avalanche Photodiode (GmAPD) detectors capable of detecting a single photon, and the area coverage rates in excess of 122 km2 /hr. The Lidar system uses an eye-safe, low-power fiber laser and a 64×64 pixel GmAPD arrays capable of readout rates in excess of 20 KHz. Although large-pixel-format GmAPD detector array can obtain plenty laser point cloud in one frame, but the requirement of raw data transmission and storage rate would be particular high when the detect repetition frequency reach at 20 KHz or even more. Therefore, we proposed a lossy realtime data compression algorithm which can reduce a half of data transmission and storage rate so that the data can transmission through low bandwidth situation. By analysis the quality of point cloud, this lossy real-time data compression method had been validated works well during our airborne experiment which had carried out in Wuhu city, China. For a single mapping strip, the point cloud had a mean measurement density greater than 110 points per square meter in flat topography and 75 points per square meter in rough topography when the aircraft above ground levels (AGLs) was 1 km and velocity was 220 km/h.