Exploiting digital imagery for snow surface retrieval on sea ice

We show how imagery from uncalibrated airborne cameras can be used to reconstruct the snow/air interface on Antarctic sea ice, using data collected on the SIPEX-II research voyage during austral spring 2012. Imagery collected by an airborne surveying package was used to develop a 3D surface model using a structure-from-motion approach. This model was validated using coincident airborne LiDAR and in situ observation of total freeboard. Our study demonstrates that equivalent surveys may be obtained using unmanned vehicles (drones) carrying only a camera and basic navigation equipment. Using this method, detailed floe-to-multifloe scale models of snow topography may be derived without logistically intensive airborne surveying programs. In turn, this allows for quick repeat surveys - simplifying the capture of a surface topography time series at any given field research site. It also allows for highly detailed analysis of relationships between surface features and how the evolve over time. Finally, we show how different surveying scenarios affect data quality and the ability to easily coregister surface models with other coincident datasets. We discuss how future surveys should be planned, which data need to be collected alongside the imagery used to generate 3D models, and where future development should be aimed at in terms of uncertainty computations and data quality assessment.