Utilizing historical aerial imagery for change detection in Antarctica
Authors: Dahle Felix , Lindenbergh Roderik , Wouters Bert 
Published: March 2024

Our research explores the potential of historical images of Antarctica for change detection in 2D and 3D. Wemake use of the TMA Archive, a vast collection of over 330,000 black and white photographs of Antarctica takenbetween 1940 to 1990. These photographs, available in both nadir and oblique, are systematically capturedfrom airplanes along flight paths and offer an unprecedented historical snapshot of the Antarctic landscape.Detecting changes between past and present observations provides a unique insight into the long-term impactof changing climate conditions on Antarctica&#8217;s glaciers, and their dynamical response to ice shelf weakening anddisintegration. Furthermore, it provides essential validation data for ice modelling efforts, thereby contributingto reducing the uncertainties in future sea level rise scenarios.In previous work, we applied semantic segmentation to these images [1]. By employing classes derived from thissegmentation, we can focus on features of interest and exclude images with extensive cloud coverage, enhancingthe accuracy of change analyses. In the next step, we geo-referenced the images: We assigned the images totheir actual position, scaled them to their true size, and aligned them with their genuine orientation. Thispresents novel opportunities for detecting environmental changes in Antarctica, particularly in the retreat ofglaciers and sea ice.Furthermore, the combination of these two steps allows for the first time a large scale reconstruction of theseimages in 3D through Structure from Motion (SfM) techniques, which enables further multidimensional changedetection by comparing historical 3D models with contemporary ones. Due to the high number of images,manual processing is impractical. Therefore, we are investigating the possibility of automatizing this process.We utilize MicMac, an open-source software developed by the French National Geographic Institute for thecreation of the 3D models. Its high modularity allows for necessary customizations to automate the SfMprocess effectively. Further adaptions are required due to the poor image quality and monotonous scenery. Bycomparing historical 3D models with contemporary ones, we can assess alterations in elevation due to factorssuch as glacial isostatic adjustments and glacier retreat.We have already employed geo-referenced images for detecting changes on the Antarctic peninsula and are in theprocess of creating initial 3D models. Our presentation will outline the workflow we developed for this processand showcase the initial results of the change detection, both in 2D and 3D formats. This approach marks asignificant step in understanding and visualizing the impacts of climate change on the Antarctic landscape.AcknowledgementsThis work was funded by NWO-grant ALWGO.2019.044.References[1] F. Dahle, R. Lindenbergh, and B. Wouters. Revisiting the past: A comparative study for semantic segmen-tation of historical images of Adelaide Island using U-nets. ISPRS Open Journal of Photogrammetry andRemote Sensing, 11:100056, 2024.