Lidar and complex sites: Poštela hillfort

Good Practice in Archaeological Diagnostics, 2013

LiDAR—like photography and other visual technologies—not only produces pictures but extends our power to detect, record, and imagine landscapes. It allows very precise three-dimensional mapping of the surface of the earth, generating as it does high-resolution topographic data even where surface is obscured by forest and vegetation. Interpretation of LiDAR data poses much more than just technical challenges. What makes LiDAR different from other topographic techniques is absence of selectiveness: data are typically gathered across complete landscape blocks recording landscape in an indiscriminate way. This allows us to address complex sites as integral parts of landscapes and as landscapes in themselves. In this way we can analyze complex sites as palimpsests, created through processes and practices that accumulated and inscribed new traces or erased old ones. Study of complex sites is thus part of the study of landscapes, landscape archaeology.

The Oxford Handbook of Mountain Archaeology, 2024

Airborne LiDAR, or airborne Light Detection and Ranging, is a remote sensing technique that measures, among other things, the terrain elevation. In the past two decades, it has become an indispensable component of landscape archaeology, especially for archaeological prospection. However, it is still infrequently used in mountain archaeology. This is especially true in the high mountains, where technical challenges make its use difficult. We can anticipate more successful applications in the future due to the ever-improving quality of data. At present, the greatest untapped potential of LiDAR data for mountain archaeology, we argue, lies in "deep" interpretation or analysis of archaeological features in their landscape context. This approach is illustrated by the case study Vodotočnik (Slovenia). We used this high mountain pasture to test the hypothesis for site location choice, which was put forward by experienced mountain archaeologists. Based on the results of six distinct geomorphometric analyses we reinterpreted the site and demonstrated the benefits of LiDAR data for modelling landscape context at the scale of individual buildings and activity areas.

Wiltshire Archaeological and Natural History Magazine, 2009

LiDAR (Light Detection and Ranging) is an aerial surveying technique that enables the creation of a digital surface model of the land. This is achieved through the saturation of the landscape by a high density of airborne ‘eye safe’ laser pulses. The time it takes for the reflected light from each pulse to return to the onboard computer is measured and the distance then calculated. This enables the creation of millions of three dimensional co-ordinates that can be joined to create a model of the surface below. Computer processing of the data can be applied to digitally remove any trees present to reveal the underlying terrain. In the woodland environment, LiDAR surveys are useful in disclosing landscape and earthwork features that are difficult to detect by using more traditional field or aerial survey techniques. A LiDAR survey of Savernake was carried out in 2006 on behalf of the Forestry Commission and has revealed a large number of previously unrecorded features of archaeological potential. These include a number of earthworks, field systems, other boundary banks, lynchets and route-ways. Comparison with known features suggests that a number are ancient in origin but other earthworks within Savernake were created over a long period of time, up to and including World War II. The landscape that is revealed by LiDAR casts new light on the historic uses of ancient woodland and forests suggesting extensive use and exploitation from prehistory until the present day. Despite the apparent success of the survey, it should be noted that LiDAR is indiscriminate and a number of features identified may be of modern origin, or given an appearance of solidity when in fact they are due to changes in vegetation. Any project involving LiDAR should be regarded as the beginning of a process of survey rather than an end result.

Laser Scanning, Theory and Applications, 2011

Geomorphology, 2013

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 DTM 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 DTMs with DSMs arises when lidar-derived DTMs 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.

Remote Sensing, 14, 6074., 2022

Archaeological heritage in woodland is undoubtedly protected from the destructive effect of modern anthropogenic activities by the presence of tree cover, which, at the same time, prevents knowledge of them and makes investigations difficult and time consuming. The tree cover makes geophysical prospection and excavations almost impossible and the use of remote sensing based on optical imagery quite ineffective. In these conditions, LiDAR is the only tool that enables us to “filter out” the canopy to reveal archaeological remains and microtopographical changes of cultural interest. A LiDAR scanner, mounted on aerial platforms, including unmanned aerial vehicles (UAVs), sends hundreds of thousands of pulses of light toward the area to be investigated. Most of them are reflected off the forest canopy and a few reach the ground and are reflected back through the canopy. Recording how long it takes the light to return to the scanner produces a point cloud. Over the past two decades, LiDAR has found increasing popularity in archaeology and has opened new perspectives in the study of the human past, revolutionizing the domain of surveying to capture and depict archaeological features under canopy. The popularity of this approach in the archaeological field is such that it has led experts to create workflows and tools for archaeology that are different from approaches used in other disciplines. Moreover, numerous studies also adopted a standard approach, consisting of: (i) raw data acquisition and processing, (ii) point cloud processing and post-processing, (iii) archaeological interpretation phase, and (iv) dissemination. The study of abandoned medieval settlements in highland areas is one of the fields of archaeological research that can greatly benefit from the use of LiDAR technology . They are the result of “social desertification” of vast territories in Europe since the first decade of the 14th century, characterized by a demographic decline occurring after four centuries of prosperity (from the 10th to 13th century) and population growth.

Sensing the Past, 2017