Thursday, December 12, 2013

Drone mapping the pyramids of Zuleta in Ecuador

The Pyramids of Zuleta are one of the hidden treasures of the Andes. Built around 1,000 years ago, by the native Caranqui people, these earthen mounds and platform pyramids dominate the landscape near Hacienda Zuleta in the mountains of northern Ecuador and 110 kilometres north of Quito.

Unlike much of our planet, high resolution aerial imagery and digital elevation models are unavailable for this part of the world. This is due to the fog that often blankets the area and the agrarian nature of the region. As a part of a team of archaeologists who visited the site in August 2013, we aimed to change that.

A challenging task

Using a small, hand-launched, Unmanned Aerial Vehicle (UAV aka drone) equipped with a downward facing camera and a sophisticated autopilot system, we documented the site as it has never been seen—from extremely low altitude and at high resolution.  This was a challenging task as most of the pyramids are located in the bottom of a steep constricted canyon inhabited by Andean Condors. To make things more challenging there were high winds, clouds, and quirks of the micro-climates within the canyon to contend with. In spite of that, we were able to fly nine missions and collect hundreds of photographs in just a couple of days.

The UAV flies in a defined pattern and collects photographs. The onboard autopilot insures that each image has 60% or more overlap with adjacent images. These overlapping images allow for the data to be processed into 3D and digital terrain models (DTMs) using photogrammetric and cutting edge Structure from Motion technologies. All of the data are GIS ready. While basic processing allowed us to see the mapped data in the field, it was necessary to further develop it using a high-end processing farm in Maryland, once we were back in the United States.

New discoveries

This approach has already led to the discovery of many more mounds that are not obvious to the naked eye but stand out in the data. Furthermore, it is the first time the detailed spatial relationship between each of the earthen structures can be explored with precision. This data will be used to track the condition of the mounds over time and has created a digital snapshot of their current state for future generations to ponder. This was accomplished with only a few days of fieldwork and under harsh conditions. To create a map of similar accuracy using traditional survey approaches would have taken weeks and lacked the aerial imagery this approach provides.

Our team has conducted similar mapping missions in Australia, Belize, Belgium, Fiji, France, Germany, The Republic of Kiribati, Peru, and South Africa. We look forward to continuing these sorts of projects elsewhere and helping to preserve and understand our past.

The archaeological mapping and processing team included Chet Walker and Mark Willis. The rest of the archaeological team was made up of Steve Athens and David O. Brown. Athens and Brown are experts on the archaeology of the Andes and have worked for decades in the region. We would like to thank Fernando Polanco Plaza, the general manager of Hacienda Zuelta, for his hospitality and dedication to preserving the rich heritage of Ecuador.

Willis, Mark. 2013. “Drone mapping the pyramids of Zuleta in Ecuador”. Past Horizons. Posted: October 29, 2013. Available online:

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