Indy Goes Geek: Laser Mapping Helps Archaeologists | Wired Science |

“This is it — the paradigm shift,” archaeologist Chris Fisher told Ars. “Just like the advent of radiocarbon dating, LiDAR will have the same impact.” LiDAR, or “light detection and ranging,” acts as a sort of radar with light, painting the target area with lasers and recording the time it takes to reflect back to the instruments. An archaeologist specializing in Western Mexico, Fisher studies the way environments affect and change cultures. LiDAR has helped him repaint the picture of ancient Mexico, bringing the little-known Purepecha empire a lot more historical prominence.

In the once tech-resistant area of anthropology, high-tech tools are enabling new discoveries on an almost daily basis. Several years ago, Fisher started out with rugged handheld computers and a few GPS receivers to map the recently discovered city Sacapu Angamuco in western Mexico, occupied from about 1,000 to 1,350 C.E. The Purepechan or Tarascan people had proven more difficult to pinpoint archeologically than had their contemporaries and rivals, the Aztecs. But initial data gathering and geo-referencing allowed Fisher to identify the city at an important moment on the crux of empire, and to do so in a fraction of the time it would have taken with tape measures and grid-plotting. Still, there was more to be done.

LiDAR is a remote sensing technology. Analogous to radar, a LiDAR array fires light at a target, often via laser. The light can be visible spectrum, ultraviolet, or near-infrared. The time it takes for the light to reflect back to the scanner is measured, with each measurement registered as a data point. In archaeology, the data thus gathered are used to plot differences in elevation and shape; from this data cloud, a picture is built up of the observed area. In addition to archaeology, LiDAR has geological, forestry, agricultural, military and meteorological uses; it’s accurate enough to chart urban environments, for instance, and to plot electric transmission lines on a map. As well as giving scientists a picture of what lies beneath them on (and under) the ground, LiDAR can even measure rain and chemicals. Though often deployed on planes that fly specially charted flight plans, covering an area with overlapping coverage strips, LiDAR can also be deployed on land-based vehicles and is even used in stationary devices to do 3-D scans of rooms and objects.

Last year, LiDAR enabled Fisher to create a full-fledged picture of the important Mesoamerican capital in greater detail. This included the discovery of several pyramids, ceremonial complexes and thousands of residences and other buildings that no one knew existed in the city. Much is known about the Purepecha at the time of European contact in the 16th century, but little has been uncovered about their origins. This project should help with that.

Just for the record, Fisher and his students aren’t looking to take down the metaphorical tree. Far from it; his Legacies of Resilience project is dedicated to understanding landscape change over time, both for the historical merit of such an investigation and for the practical purposes of understanding our own future. Fisher and his team seek to understand how the environment allowed for the development of a people capable of limiting Aztec expansion.

Pure science is not the only rationale for the use of LiDAR and other technologies. In a tight economic time, academic funds are sparser that usual, so anything that can save money is welcome.

FULL ARTICLE: Indy Goes Geek: Laser Mapping Helps Archaeologists | Wired Science |

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