Interpreting cultural remains in airborne laser scanning generated digital terrain models: effects of size and shape on detection success rates

In this study, detection success rates were evaluated for cultural remains that were detected manually based on interpretation of digital terrain models (DTM) derived from airborne laser scanning data and with a resolution of 1, 5 and 10 points m⁻². The group of cultural remains included charcoal kilns, charcoal pits, hollow-roads, various pits, house foundations, tar kilns, grave mounds and pit-falls. The effects on the interpretation success of different types of cultural remains and their physical properties were studied: size, shape and elevation difference showing that the detection success rates varied considerably. The main tendency was that large cultural remains with clear geometrical shape (ovals and circles) and large elevation difference were much more successfully detected and classified compared to the smaller ones, especially those without a clear geometrical shape. The study also showed that it was the identification of the larger structures which profited most from an increased resolution of the DTM, and it was of no help to increase resolution in order to improve the identification of the irregularly shaped cultural remains.     

Using airborne small-footprint laser scanner data for detection of cultural remains in forests: an experimental study of the effects of pulse density and DTM smoothing

Cultural remains are laborious to register by means of field surveys. Thus, in recent years several trials using remote sensing data to detect cultural remains have been carried out. The most promising remote sensing technique for such purposes is airborne laser scanning (ALS) from which digital terrain models (DTM) that enable visual interpretations of anomalies on the ground are generated. Although it has been documented previously that ALS is a powerful data source for detection of cultural remains, it has not yet been carried out studies that focus on the effects of the point density of the ALS data and properties of the subsequent generation of the DTM on the detection success of cultural remains. Thus, this study aimed at analyzing these effects by letting four experienced archeologists interpret DTMs generated from ALS data with point densities of 1 p m⁻², 5 p m⁻², and 10 p m⁻², each with three different levels of DTM smoothing. The experiment was conducted according to a randomized complete block design and the analyses were carried out using analysis of variance. The results showed that there was a significant improvement in the detection success when the point density was increased from 1 p m⁻² to 5 p m⁻². There were also some improvements when increasing the point density further to 10 p m⁻², but they were less pronounced. Furthermore, the results showed that the DTM smoothing did not have any significant effect on the detection success.