Lidar Survey

Origin and history

Lidar, an acronym for Light Detection and Ranging, originated as a developed technology in the United States during the 1960s. Its initial development was driven by meteorology for cloud height measurement and by the military for precise ranging. The foundational principle, however, dates back to the early 1930s with early experiments in using light for distance measurement. The technology evolved significantly with the invention of the laser, which provided the necessary coherent light source. Widespread archaeological adoption began in the late 1990s and early 2000s as airborne systems became more compact and affordable. The pivotal shift for landscape archaeology came with the ability to digitally remove forest canopy, revealing human-made terrain modifications hidden for centuries.

What it is for

A lidar survey is primarily used for creating high-resolution, three-dimensional maps of the Earth's surface and the features upon it. In archaeology, its core function is to detect and record micro-topographic anomalies that represent cultural features, such as building platforms, field systems, roads, and fortifications. It is specifically for rapidly surveying large, topographically complex, or visually obscured areas, like dense forest or jungle, that are impractical for traditional field walking. The data products, including digital elevation models and point clouds, serve as a primary dataset for planning targeted ground investigation. It is not for identifying specific artifact types or dating features directly from the scan data. The survey provides a spatial framework upon which material culture evidence, recovered through excavation, can be contextualized and understood.

Pros and cons

It dramatically increases survey speed and coverage compared to traditional methods, making it cost-effective for large areas. A major con is that it only records surface and near-surface topography; it cannot see beneath the ground, meaning features without topographic expression or buried deeply are missed. The technology also generates vast, complex datasets that require significant expertise in GIS and point cloud software to process and interpret correctly. A common mistake is treating the visual hillshade models as definitive maps rather than interpretive products, potentially leading to misidentification of natural features as archaeological. Projects often regret the choice when applied to flat, open, ploughed landscapes where traditional geophysics or surface collection would yield more directly useful data about sub-surface features and artifact distributions.

Who it suits

This method suits archaeological projects focused on landscape archaeology in regions with dense vegetation or difficult terrain, such as tropical forests or rugged uplands. It is ideal for research aiming to understand the full extent of a known site's hinterland or to conduct reconnaissance in a poorly studied region. Cultural resource management firms working on large-scale infrastructure projects in forested areas use it for efficient heritage assessment. It does not suit projects with very limited budgets or those focused exclusively on excavating deeply stratified urban centers with no surrounding landscape component. The method requires a team with specific skills in spatial data analysis, making it less suitable for groups lacking such technical capacity. It is also highly suitable for interdisciplinary projects combining archaeology with ecology or geology, where detailed terrain models are a shared resource.