Generating Impact Maps From Automatically Detected Bomb Craters in Aerial Wartime Images Using Marked Point Processes

Abstract

ABSTRACT:The aftermath of wartime attacks is often felt long after the war ended, as numerous unexploded bombs may still exist in the ground. Typically, such areas are documented in so-called impact maps which are based on the detection of bomb craters. This paper proposes a method for the automatic detection of bomb craters in aerial wartime images that were taken during the Second World War. The object model for the bomb craters is represented by ellipses. A probabilistic approach based on marked point processes determines the most likely configuration of objects within the scene. Adding and removing new objects to and from the current configuration, respectively, changing their positions and modifying the ellipse parameters randomly creates new object configurations. Each configuration is evaluated using an energy function. High gradient magnitudes along the border of the ellipse are favored and overlapping ellipses are penalized. Reversible Jump Markov Chain Monte Carlo sampling in combination with simulated annealing provides the global energy optimum, which describes the conformance with a predefined model. For generating the impact map a probability map is defined which is created from the automatic detections via kernel density estimation. By setting a threshold, areas around the detections are classified as contaminated or uncontaminated sites, respectively. Our results show the general potential of the method for the automatic detection of bomb craters and its automated generation of an impact map in a heterogeneous image stock.

Bombed Archaeology: Towards a Precise Identification and a Safe Management of WWII’s Dangerous Unexploded Bombs

“…This project proposes a more cost-effective and easier method for locating dangerous unexploded bombs than the intense ground methods and complex programming computer-based methods that have previously been used to locate possible dangerous unexploded bombs [18][19][20][21][22][23][24].…”

“…Nevertheless, the mere mapping of all the aerially visible bomb craters from the various aerial photos in the archives constitutes a certain basis of knowledge [18]. However, the possibility of using a multi-temporal imagery dataset together with non-destructive techniques (NDTs), such as ground penetrating radar (GPR), can help in better understanding the presence of possible dangerous unexploded bombs in the subsurface [19][20][21]. Moreover, real-time maps (i.e., maps produced right after the acquisition of the data directly on-site) can be created with a precise location of these hidden bombs close to archaeological and touristic areas, thereby protecting historical knowledge, the Italian territory, and the people who frequent it [22].…”

Marked Point Processes for the Automatic Detection of Bomb Craters in Aerial Wartime Images

“…The cited articles and our previous work (Kruse et al, 2018) show the potential of stochastic methods based on MPPs in 1(3)…”

“…configuration, a probability map is created by kernel density estimation which allows to differentiate between potentially contaminated and uncontaminated areas (Section 3.6). Parts of the methodology presented in this paper are based on (Kruse et al, 2018), which provides more information about some topics.…”

“…In this work, we use MPPs to detect bomb craters in aerial wartime images, building on (Kruse et al, 2018), where craters were represented as ellipses; the results showed the potential of the method. During sampling, high magnitudes of the grey value gradients at the ellipse borders are favoured and an overlap of ellipses is penalized.…”