Smartphone assisted fieldwork. Towards the digital transition of geoscience fieldwork using LiDAR-equipped iPhones

Major advances in smartphones and tablets in terms of their built-in sensors (esp. cameras), available computational power and on-board memory are transforming the role of such devices into the key digital platform around which geological fieldwork is redesigning itself. This digital transition is changing how geoscientists collect and share multimodal-multidimensional field datasets, which can now be readily distributed via standardized exchange formats and online data repositories. The increased accessibility of digital field datasets means that such data products are no longer the sole preserve of geospatial/geoscience specialists, but also students, stakeholders and the general public alike, providing great opportunities for knowledge transfer over the entirety of the research value chain. In the wake of this digital transition, the geological community has welcomed with enthusiasm and curiosity the introduction during 2020 of a native LiDAR scanner equipped on both the iPad Pro and the iPhone 12 Pro. This scanner offers a potential paradigm shift in digital geological fieldwork and puts these devices at the forefront of smartphone assisted fieldwork. In this work, we review progress in smartphone/tablet assisted geological fieldwork and test the iPhone 12 Pro's effectiveness as a replacement for conventional geological field tools. Specifically, we evaluate the geo-location accuracy of the iPhone's Global Navigation Satellite System (GNSS) receiver, the effectiveness of its inertial measurement unit (IMU) and magnetometer for orientation data collection, its photo-video imaging capabilities, and the performance of the device's newly equipped LiDAR in the field. We demonstrate that the performance of the iPhone for orientation and raster image data capture is high, being comparable to analog compass-clinometers and reflex/mirrorless cameras. Whilst location error is within the order of a few meters, the level of accuracy and the fast stabilization of the signal means that, beyond survey grade applications, the iPhone's geo-location capabilities are acceptable for most field cases. With regards to the iPhone's built-in LiDAR scanner, it is an excellent tool for depth assisted camera focusing and for casual 3D outcrop sharing, especially for ‘soft’ applications such as geo-heritage documentation and the production of teaching materials (here we also propose a simple mode of uploading outcrops models in Google Maps). However, the generated 3D models in some cases may be considered overly crude for detailed interrogation, particularly where the fidelity of the surface reconstruction is critical to the analysis (e.g. mesh facet orientation estimation). Based on our review of the evolution of digital field acquisition technologies and on our extensive field testing of the sensor suite integrated within the iPhone 12 Pro, it is clear that the digital transition of geological fieldwork is already mature, whereby smartphone devices have become as indispensable in the field as the geologists' traditional hammer and hand lens.