Imaging the Waters of Angkor: A Method for Semi‐Automated Pond Extraction from LiDAR Data

Abstract

This article presents new archaeological data concerning the Greater Angkor region, home to successive capitals of the medieval Khmer Empire from the ninth to fifteenth centuries ad. Angkor is recognized as one of the most extensive low‐density urban complexes of the pre‐industrial world. One of the most striking features in the landscape of Angkor is the enormous assemblage of hydraulic infrastructure, including two artificial reservoirs each covering around 15 km2. However, in parallel to this massive, state‐level system of water management, we also see evidence at Angkor of a smaller‐scale system of household or community ponds in the urban core. These were described by the Chinese envoy Zhou Daguan, who visited Angkor in the late thirteenth century ad. His account includes the important information that each cistern was used by one to three families. The validity of this historical account can now be assessed using a precise map of the archaeological landscape that was created in 2012 using airborne laser scanning (‘ALS’ or ‘LiDAR’, light detection and ranging). The LiDAR data allow us to arrive at new insights into the demography of medieval Angkor. Using an algorithm for semi‐automatic pond detection in the ALS‐derived data it was possible to map over three thousand cisterns and from this to make inferences about population density in central Angkor. Copyright © 2015 John Wiley & Sons, Ltd.

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