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Ancient Amphipolis (Eastern Macedonia, Greece) is one of the most important archaeological sites of Greece. Despite the restricted excavation studies, important monuments have been discovered, such as the city walls and the Macedonian burial site at the Kasta hill, etc. Currently, the location of the ancient theater is unknown and only assumptions can be made regarding its location. In the current study, we aim to detect the accurate location of the ancient theater using archaeological prospection tools, data collected from the excavated sites, and testimonies of people of the modern city. For the first step of the approach, the approximate location of the ancient theater was determined using information derived by archived geospatial data (multi-temporal aerial photographs, satellite image, and Digital Terrain Model (DTM) of the area) as well as information regarding the neighboring excavated sites. For the in-depth study of the area of interest, a drone was used for the acquisition of high-resolution geospatial data. The generated orthorectified image (3 cm spatial resolution), DTM, and Digital Surface Model (DSM) allowed the determination of the potential location of the buried orchestra’s center using geometric rules for the design of ancient theaters. Furthermore, using the produced DSM and DTM, terrain cross-sections were generated.

The focus of this chapter is the contribution of remote sensing (RS) technologies in climate risk mainly for archaeological landscapes and built heritage. It will study the use of RS technologies for sea level rise scenario risk assessment and the use of multi-temporal multisource data and statistical indices for the detection of changes in built heritage. This chapter is divided in two sections: the first one focuses on sea level rise and potential threats, while the second one focuses on monitoring of temporal changes in built heritage using multisource multi-temporal data and indices.

Remote sensing facilitates the extraction of information for earth’s surface through its capability of acquiring images covering large areas and the availability of commercial software for their processing. The aim of this study is the feature extraction from three Geoeye-1 stereo pairs for forested area. The study area is located in central mountainous forested peninsula of Chalkidiki, in northern Greece. Dominant forest tree species of the site are oak (Quercus conferta), beech (Fagus moesiaca), black pine (Pinus nigra) and calabrian pine (Pinus brutia). Very High Resolution (VHR) Geoeye-1 stereo pair satellite images were utilized in panchromatic and multispectral mode. The panchromatic mode was employed for Digital Surface Model (DSM) generation and its evaluation. In this study the High Pass Filter (HPF) data fusion technique was applied between panchromatic and multispectral mode for acquiring a new image with the benefits of both contracting images. Because of the fact that the feature extraction was attempted in a forested region, NDVI index and Tasseled Cap transformation were applied in the fused images’ evaluation procedure. Optical assessment was also applied. The accuracy of the generated DSM and the evaluation results of the fused images were remarkable.

Within the field of forestry, forest road mapping and inventory plays an important role in management activities related to wood harvesting industry, sentiment and water run-off modelling, biodiversity distribution and ecological connectivity, recreation activities, future planning of forest road networks and wildfire protection and fire-fighting. Especially in countries of the Mediterranean Rim, knowledge at regional and national scales regarding the distribution and the characteristics of rural and forest road network is essential in order to ensure an effective emergency management and rapid response of the fire-fighting mechanism. Yet, the absence of accurate and updated geodatabases and the drawbacks related to the use of traditional cartographic methods arising from the forest environment settings, and the cost and efforts needed, as thousands of meters need to be surveyed per site, trigger the need for new data sources and innovative mapping approaches. Monitoring the condition of unpaved forest roads with unmanned aerial vehicle technology is an attractive option for substituting objective, laboursome surveys. Although photogrammetric processing of UAV imagery can achieve accuracy of 1-2 centimeters and dense point clouds, the process is commonly based on the establishment of control points. In the case of forest road networks, which are linear features, there is a need for a great number of control points. Our aim is to evaluate low-cost UAV orthoimages generated over forest areas with GCP’s captured from existing national scale aerial orthoimagery, satellite imagery available through a web mapping service (WMS), field surveys using Mobile Mapping System and GNSS receiver. We also explored the direct georeferencing potential through the GNSS onboard the low cost UAV. The results suggest that the GNSS approach proved to most accurate, while the positional accuracy derived using the WMS and the aerial orthoimagery datasets deemed satisfactory for the specific task at hand. The direct georeferencing procedure seems to be insufficient unless an onboard GNSS with improved specifications or Real-Time Kinematic (RTK) capabilities is used.

The study refers to the visual representation of the coastal front of the historical center of Thessaloniki in northern Greece and its changes that have occurred through the years. Most of the old town was destroyed by fire on August 18, 1917. A few years later, the French architect and archeologist Ernest Hebrard proposed the reconstruction of the city centre, but his plans were never fully implemented. Since then, a series of interventions changed the form of the old town and consequently the coastal cityscape. The research was initially based on the photogrammetric processing of archive aerial images (1938) of Thessaloniki's city centre. Besides the vertical images, high oblique aerial images dated back to 1932, proved to be a significant source of information. A rich archive of old photographic material, sketches, drawings and gravures of the coastal forehead of the city was also used. Ortho-images of the coastal front, derived from laser scanning (2010), and a 3D model of the historical city center, derived from the stereo photogrammetric process of aerial images (1990), contributed decisively at the multi temporal study of the city front. The main outcomes of the present documentation study are the 3D representation (at scale of 1:200, accuracy 5 cm) of temporal changes of a part of the coastal front of the historical center of Thessaloniki and the 2D representation (at scale 1:100, accuracy 1–2 cm) of these changes with respect to variations on skyline, lacunas, interventions in old buildings, etc.

In this paper, we address the orientation of ground-level motion imagery captured by sensors roaming in an urban area. We investigate the use of building facades (instead of traditional points), as matching features for ground-level motion imagery orientation. We assume a situation where few images in our sequence are already absolutely oriented, and present a novel approach to orient all remaining inbetween image sequences relative to them. This innovative version of dependent orientation allows us to propagate orientation information within sequences of ground level imagery, establishing a novel orientation scheme. Experimental results show accuracies on the order of 0.18 to 0.29 degrees in rotation estimation, and 0.17 to 0.29 meters in camera position determination.

Balkan countries do not have a coherent and continuous approach towards the challenge of implementing integrated Earth Observation (EO) applications in environmental monitoring and management. Most of the Balkan countries, except Greece, are not full ESA members. Additionally, Albania, Serbia, Bulgaria, FYROM, Montenegro and Bosnia Herzegovina are also not members of the Group on Earth Observation (GEO). The OBSERVE Research Programme, funded under the theme "ENV.2010.4.1.4-1, Identification and Networking of EO activities in the Balkan area" and with a full title "Strengthening and Development of Earth Observation Activities for the Environment in the Balkan Area," has as its main objectives to collect and compile all the necessary information for delivering an integrated analysis on the current status of EO activities and networks in the Balkans regarding environmental monitoring, and to determine the potential benefit from the full exploitation of an integrated capacity development strategy and the prospect of creating a relevant permanent EO Community in the broader region. One of the most important activities to accomplish the above mentioned objectives is the collection and compilation of the National Thematic Reports concerning EO capacities delivered by the separate Balkan participants in the Project.