Ralf HESSE
(State Office for Cultural Heritage, Esslingen am Neckar, Germany)
Keywords: monitoring, change detection, airborne lidar, ALS
Abstract:
High-resolution digital elevation models (usually based on airborne laser scanning) have been applied for archaeological research for more than ten years. In some regions, repeated coverage is becoming available, resulting in opportunities for the detection of changes which have occurred in-between the different surveys. However, while DEM change detection is in principle very simple, the practical application faces a number of challenges. These challenges include spatial resolution, horizontal and vertical accuracy as well as impacts of vegetation cover and data processing (e.g. strip adjustment and vegetation filtering). In addition to these challenges, the issue of comparing digital terrain models with digital surface models arises when lidar-derived DEMs are supplemented with lower-cost and often more easily acquired photogrammetric DSMs. As a result, the seemingly straightforward approach to monitoring archaeological landscapes by analysing multi-temporal elevation data
sets is limited with respect to the detectability of relief changes and the achievable accuracy of the quantification of such changes. Because of the ongoing developments in terms of spatial resolution and accuracy, it is usually the (older) baseline data set which limits the applicability and informative value of change detection approaches. Therefore, it is expected that large area monitoring schemes based on airborne lidar will only become operational once repeated coverage by high-quality surveys becomes available. However, results achieved in small test areas in Baden-Württemberg are promising despite the mentioned challenges.