(Photo: NEON Science, CC BY 2.0)

All roads lead to Rome, or Chichén Itzá in this case, as the capital belonged to an empire that matched the urban planning feats of the city founded by Romulus and Remus.

This has been demonstrated by recent studies performed with Lidar (Light Detection and Ranging), a system that consists of obtaining images by emitting millions of laser pulses. When these hit the ground, they bounce off and enable archeological remains to be digitally recreated over large areas of land, even if they’re under dense vegetation.

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Large numbers of pulses can reach the ground when they’re projected from drones or aircraft, so the lie of the land can be learned in such detail that the image can record alterations made to the surface by ancient inhabitants.

“We usually take 15 laser points per square meter. This is used to generate a scatter diagram. The different classifications of this diagram generate a topography for the ground, thanks to mathematical algorithms that can remove the effect caused by vegetation,” says José Luis Punzo Díaz, an archeological research professor from the National Institute of Anthropology and History (INAH), in an interview with Tec Review.

This expert mentions that Lidar pulses are stopped by the first solid surface they find. For instance, most pulses hit vegetation in Maya jungles where there is a very thick tree canopy, but some go through it and hit the ground.

“When we obtain the scatter diagram, we see that some of them hit the part above and others hit the middle, on any bushes that are there. That allows us to remove all the points from above and make a topographical map of the lower part, i.e. the points that hit the ground,” explains Punzo Díaz.

Lidar has been used for the past five years to look for ruins in the Maya area of the Yucatán peninsula, above all in regions with very high plant density where it is hard to observe archeological elements with the naked eye.

Rodrigo Esparza López, a research professor from Michoacán College’s Center for Archeological Studies, has the following to say, “This is one of the places where this technology began to be implemented. It’s revolutionized how we find archeological sites, in terms of the detail that Lidar analysis has provided. We knew that the Maya were like the Romans, excellent road-making engineers, but it was only when we could see these trails throughout the peninsula with Lidar that we realized how true this was. We were quite impressed.”

Esparza López, who also holds a specialization in archaeometry from the National School of Anthropology and History (ENAH), mentions that teams from US universities have collaborated with Mexican researchers to perform Lidar studies over a large part of the Yucatán peninsula. They have found a wealth of archeological sites, practically double the number reported previously. What’s more, those already recorded turned out to be bigger than people had thought before.

“In general, Lidar has been used to guide and plan excavations. For instance, an impressive site was recently found in Tabasco. Thanks to this technology, they were able to identify one of the biggest structures in Maya culture: it’s nearly 500 meters long. If we didn’t have this tool, it wouldn’t have been so easy to make that discovery,” explains Esparza.

Both experts agree that Lidar marks a watershed for the archeology of this century. However, it is still a very expensive technology. When it begins to come down in price, as happens with all technologies, it will surely become more accessible in Mexico and enable many other surprising finds to be made.

“In the future, Lidar will be used in Mexico as one more very necessary step when a large-scale investigation is to be made, to have a clearer idea of the land to be explored and thus have an x-ray photograph of each archeological site,” says Esparza.

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The Lidar Technology (Light Detection and Ranging) (Phpto: NEON Science, CC BY 2.0)

Will technology replace archaeologists?

Both specialists agree that in a time when the use of sophisticated software has replaced many of the tasks performed by human beings, archeology will still require the fieldwork and intelligence of researchers.

“Lidar cannot encompass all the work of an archaeologist, as it’s never going to be able to do such a meticulous job. This technology is used at the level of an archeological survey, i.e. finding ruins on the land. After that comes the excavation and finally analysis of the materials,” says Esparza.

Punzo, who holds a PhD in archeology from the ENAH, says that the true challenge and greatest amount of time spent on the work doesn’t have to do with acquiring the information, but with the specialized tasks that archaeologists have to perform afterwards.

“We shouldn’t lose sight of the fact that the technology only offers mathematical models, not what’s actually there. What the sensor locates, and we process and interpret as an archeological feature, won’t be confirmed until we go into the field,” concludes Punzo. “People often think that Lidar replaces the archeological work on the ground. That’s not the case. It’s simply a great tool, but it’s not a magic bullet. You still have to hike through the jungle.”

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