Historical Images for Surface Topography Reconstruction Intercomparison eXperiment (HistoriX)

Abstract. Historical film-based images, acquired during aerial campaigns since the 1930s and from satellite platforms since the 1960s, provide a unique opportunity to document changes in the Earth’s surface over the 20th century. Yet, exploiting these rich data presents significant and specific challenges, including complex distortions in the scanned images and poorly known exterior and/or interior camera orientation. In recent years, semi- or fully-automated approaches based on photogrammetric and computer vision methods have emerged, but their performance and limitations have not yet been evaluated in a consistent way.The ongoing project “Historical Images for Surface Topography Reconstruction Intercomparison eXperiment (HistoriX)” aims at comparing existing methods for processing stereoscopic historical images and harmonizing processing tools. Within this experiment, participants were provided with a standardized set of historical images and available metadata, then invited to produce a point cloud and estimated camera parameters. We selected two study sites and three sets of film-based images acquired coincidently in the 1970s or 80s from airborne or satellite platforms. The submitted elevation data are currently being cross-validated across different image sets and participant submissions, as well as against reference elevation data over stable terrain. The spread in the retrieved elevations is analysed with respect to image type, terrain type and processing methods to highlight the strengths and limitations of the different approaches. Here we present the study site and datasets selected for this comparison, the design of the intercomparison and evaluation metrics, as well as preliminary results.