High-resolution high-accuracy orthophoto map and digital surface model of Forni Glacier tongue (Central Italian Alps) from UAV photogrammetry

This work presents the high-resolution high-accuracy orthophoto map and the Digital Surface Model of Forni Glacier (Italian Alps). These represent the status of the glacier tongue in mid-August 2022 when surveys were carried out with a DJI Phantom 4 RTK drone. The processing was carried out in Leica Infinity, and a 3 cm orthomosaic and a 20 cm Digital Surface Model were generated and made available for analysis of the current status of the glacier, which shows signs of downwasting, with the occurrence of collapsing areas and a rapidly changing proglacial landscape. This work can also be used as a reference to investigate the glacier evolution, also in light of climate change. Accuracy requirements of the deliverables were ensured by combining Post Processed Kinematic and Structure from Motion integrated with bundle block adjustment, and using Ground Control Points and Check Points, to guarantee redundancy and evaluate the geolocation accuracy and precision.

本研究发布了意大利阿尔卑斯山脉福尔尼冰川（Forni Glacier）的高分辨率高精度正射影像图（orthophoto map）与数字表面模型（Digital Surface Model, DSM）。上述数据展现了2022年8月中旬该冰川舌的现状，彼时研究团队使用DJI精灵4 RTK（Phantom 4 RTK）无人机完成了外业测量。后续数据处理在徕卡Infinity（Leica Infinity）软件中完成，最终生成了分辨率为3厘米的正射镶嵌图（orthomosaic）与20厘米分辨率的数字表面模型，可供该冰川当前状态的分析研究使用。当前该冰川已显现消融衰退迹象，存在坍塌区域，且冰前景观正快速变化。本研究成果亦可作为气候变化背景下冰川演化调查的参考依据。为保障成果满足精度要求，研究团队结合后处理动态定位（Post Processed Kinematic, PPK）与集成光束法区域网平差（bundle block adjustment）的运动恢复结构（Structure from Motion, SfM）技术，并辅以地面控制点（Ground Control Points, GCP）与检查点（Check Points, CP）以保证观测冗余度，同时完成了地理定位准确度与精度的评估。