A LIGHTWEIGHT UAV-BASED LASER SCANNING SYSTEM FOR FOREST APPLICATION

Abstract Lightweight Unmanned Aerial Vehicles (UAVs) have become a cost effective alternative for studies which use aerial Remote Sensing with high temporal frequency requirements for small areas. Laser scanner devices are widely used for rapid tridimensional data acquisition, mainly as a complementary data source to photogrammetric surveying. Recent studies using laser scanner systems onboard UAVs for forestry inventory and mapping applications have presented encouraging results. This work describes the development and accuracy assessment of a low cost mapping platform composed by an Ibeo Lux scanner, a GNSS (Global Navigation Satellite System) antenna, an Inertial Navigation System Novatel Span-IGM-S1, integrating a GNSS receiver and an IMU (Inertial Measurement Unit), a Raspberry PI portable computer and an octopter UAV. The system was assessed in aerial mode using an UAV octopter developed by SensorMap Company. The resulting point density in a plot with trees concentration was also evaluated. The point density of this device is lower than conventional Airborne Laser Systems but the results showed that altimetric accuracy with this system is around 30 cm, which is acceptable for forest applications. The main advantages of this system are their low weight and low cost, which make it attractive for several applications.

摘要 轻型无人机（Unmanned Aerial Vehicles, UAVs）已成为针对小区域且具备高时间频率需求的航空遥感研究的高性价比替代方案。激光扫描仪设备广泛应用于快速三维数据采集，主要作为摄影测量的补充数据源。近期搭载激光扫描仪系统的无人机在林业清查与制图应用中的相关研究已取得令人鼓舞的成果。本研究阐述了一套低成本制图平台的开发与精度评估工作，该平台由Ibeo Lux激光扫描仪、全球导航卫星系统（Global Navigation Satellite System, GNSS）天线、集成GNSS接收机与惯性测量单元（Inertial Measurement Unit, IMU）的诺瓦泰尔Span-IGM-S1惯性导航系统、树莓派便携式计算机以及八旋翼无人机组成。本研究采用SensorMap公司研发的八旋翼无人机开展机载测试。此外，还对林木密集样地的点云密度进行了评估。该设备的点云密度低于传统机载激光系统，但测试结果显示，本系统的测高精度约为30厘米，可满足林业应用的需求。本系统的核心优势在于重量轻、成本低，因而使其在诸多应用场景中具备吸引力。