Archaeological Application of Airborne LiDAR with Object-Based Vegetation Classification and Visualization Techniques at the Lowland Maya Site of Ceibal, Guatemala

Abstract

Abstract:The successful analysis of LiDAR data for archaeological research requires an evaluation of effects of different vegetation types and the use of adequate visualization techniques for the identification of archaeological features. The Ceibal-Petexbatun Archaeological Project conducted a LiDAR survey of an area of 20 × 20 km around the Maya site of Ceibal, Guatemala, which comprises diverse vegetation classes, including rainforest, secondary vegetation, agricultural fields, and pastures. We developed a classification of vegetation through object-based image analysis (OBIA), primarily using LiDAR-derived datasets, and evaluated various visualization techniques of LiDAR data. We then compared probable archaeological features identified in the LiDAR data with the archaeological map produced by Harvard University in the 1960s and conducted ground-truthing in sample areas. This study demonstrates the effectiveness of the OBIA approach to vegetation classification in archaeological applications, and suggests that the Red Relief Image Map (RRIM) aids the efficient identification of subtle archaeological features. LiDAR functioned reasonably well for the thick rainforest in this high precipitation region, but the densest parts of foliage appear to create patches with no or few ground points, which make the identification of small structures problematic.

Ancient lowland Maya complexity as revealed by airborne laser scanning of northern Guatemala

“…Overall, approximately 165 km 2 within the study area have either been used as training samples, subsequently "ground-truthed," or both (Table 3); that is, 7.7% of the entire PLI survey region has been verified through ground survey, although mapped areas were not uniformly distributed (Table 3). Moreover, all field teams within the PLI study region have ground-validated features belonging to every class reported on here: buildings of various types, defensive features, upland and wetland agricultural features, causeways, canals, and reservoirs.…”

Beyond the magic wand: methodological developments and results from integrated Lidar survey at the ancient Maya Center El Pilar

“…We have found the bonemap to be one of the most effective visualizations for identifying architecture, although features such as depressions and drainages are most apparent in the bare-earth hillshade visualization. We therefore retain different visualizations, including slope and aspect rasters, for comparison in ArcGIS and will continue to experiment with alternative visualization methods (e.g, the Red Relief Image Map [Inomata et al 2017] and Prismatic Openness [Canuto et al 2018]). Analysts mark potential features on the master GIS map by creating "go-to points" in a point shapefile.…”

Relief visualization techniques using free and open source GIS tools

“…Chiba, B. Hasi 2016). Other versions of red relief are combination of hillshade (one direction) and slope (M. Doneus, T. Kühteiber 2013) and combination of SVF (gray) and red slope overlay (T. Inomata et al 2017). Here we presented another version which is a combination of red slope base layer (stretch with 2% clip) with two directional hillshade overlay (stretch to min-max, 70% transparency, blending mode: normal) ( fig.…”