Aerial photography
Aerial archaeology is a very cost-effective method for site discovery with the potential to provide detailed maps of archaeological structures, showing up on the surface as so called "visibility marks", i.e. slight topographic variations visible as shadow-marks, soil-marks due to varying chemical and physical properties affecting soil colour on the surface, and crop-marks due to variable growth of the vegetation or frost-marks due to varying thermal properties. Georeferenced and rectified vertical and oblique aerial photos from reconnaissance flights are used to derive the archaeological interpretation of detected structures or features. In that way, repetitive observations can be combined into an extensive overall view of an archaeological region, which will be used as basic information for further prospecting, excavations, protection measures, and spatial archaeology.