Tag Archives: lidar

Archaeologists uncover hidden citadel in ancient Maya city

Using airborne data, a group of archaeologists discovered a previously unknown structural complex near the Maya city of Tikal, in what is now Guatemala. While the city is notable in itself, what makes the discovery even more interesting is that the complex’s structures are similar to buildings in Teotihuacan, a Mesoamerican city. 

View of the Teotihuacan Complex at Tikal. Image credit: Researchers

The ruins of Tikal have been the subject of extensive study since the 1950s, with researchers documenting details of every structure and cataloguing all excavated items. This has made Tikal one of the best understood archeological sites in the world. Nevertheless, there’s always something new to discover — as we can see in this study. 

Stephen Houston from Brown University and Thomas Garrison from the University of Texas have discovered that what was thought to be a natural hilly area near Tikal’s center was actually a neighborhood of ruined buildings intentionally designed to look like Teotihuacan, the most powerful and largest city there was in ancient Americas.

“What we had taken to be natural hills actually were shown to be modified and conformed to the shape of the citadel,” Houston said in a statement. “Regardless of who built this smaller-scale replica and why, it shows without a doubt that there was a different level of interaction between Tikal and Teotihuacan than previously believed.”

Understanding Tikal

The area where the complex was found hadn’t been explored until now as researchers believed that the hills were just part of the natural landscape. Houston and Garrison used LIDAR, a light detection and ranging technology, to build 3D models of the surface and identify structural features. This was followed then by an on-site exploration that confirmed the findings.

In the area, which is roughly 62 acres, the researchers confirmed with excavations that the buildings were built with mud plaster than limestone, a material usually used by the Maya society. In fact, the structures appeared to be scaled-down versions of the buildings from Teotihuacan’s citadel, located more than 1,000 kilometers (621 miles) away. 

The researchers also found human remains near the replicated buildings. The bodies were surrounded by several funerary items such as animal bones and projectile points. There was also plenty of coal, suggesting the assemblage was deliberately set on fire – a death ritual that is similar to the one used with warriors at the citadel of Teotihuacan. 

It’s not the first-time evidence is found of the influence of Teotihuacan in Tikal, as contacts between the two societies were common. Maya elites lived and traded in Teotihuacan. But after centuries of peace, Teotihuacan conquered Tikal in 378 CE.  The new findings suggest a more intense contact between the two, the researchers argue.

“The architectural complex we found very much appears to have been built for people from Teotihuacan or those under their control,” Houston said. “Perhaps it was something like an embassy complex, but when we combine previous research with our latest findings, it suggests something more heavy-handed, like occupation or surveillance.”

The study was published in the journal Antiquity. 

Ancient Maya ruins digitized by laser aerial survey

Archaeology in the 21st century looks radically different than what you might expect. While archaeologists still get their boots wet and perform fieldwork, trowels and picks in hand, their modern toolkit also includes artificial intelligence algorithms that reveal new hidden statistical patterns in ancient samples or state-of-the-art lasers that shoot billions of beams per minute from an aircraft onto the ground. It’s this latter combination of lasers, known as LIDAR, and AI that allowed researchers to uncover hidden ancient Maya ruins that had been obstructed by vegetation and the wear of the passing centuries.

3D image of Labna, an ancient Maya structure in the Puuc region. Credit: Proyecto Arqueológico Regional de Bolonchén.

Thanks to LiDAR (light detection and ranging) technology, archaeologists don’t have to wander endlessly through the jungle in search of artifacts and hidden ruins. By strapping LiDAR to a low-flying aircraft, it’s possible to survey thousands of square kilometers of terrain at a time.

LiDAR or 3D laser scanning was developed in the early 1960s for submarine detection from an aircraft. It works by generating a laser pulse train that can travel through the gaps of dense vegetation. By calculating the time it takes for the laser pulse to reflect back to its source, researchers can determine the elevation of the ground. This way, archaeologists can identify human-made features on the ground, such as walls, roads, and buildings.

Archeologists have put LIDAR to good use while surveying Mayan sites before. In 2018, LIDAR revealed more than 60,000 hidden Maya structures at the site of Tikal in Guatemala. In 2020, the laser-based tech led to the discovery of the largest and oldest Maya monument, found in the Mexican state of Tabasco.

Now, LIDAR has been deployed to the northern Yucatán Peninsula, at an area of limestone hills and valleys known as the Puuc region, in present-day Mexico. Appropriately, Puuc is the Maya word for “hill”.

It was at Puuc that one of the greatest Mayan cities, Uxmal, evolved, reaching its apogee between AD 600 and 900. William Ringle, a professor emeritus of anthropology at Davidson College in North Carolina, has spent over 20 years doing groundwork in the Puuc region, which is home to four large acropolises that had been documented since the 1940s. But thanks to a few LIDAR aerial surveys in 2017, Ringle’s team discovered more about the Maya site than in the past two decades.

Ruins of a two-story Maya palace. Credit: Proyecto Arqueológico Regional de Bolonchén.
Another Maya ruin from Puuc. Credit: Proyecto Arqueológico Regional de Bolonchén.
A ruined structure that used to divide the Plaza Icim from the Plaza Yaxche in the Puuc region. Credit: Proyecto Arqueológico Regional de Bolonchén.

Writing in a study published this week in the journal PLOS One, Ringle and colleagues described how they identified over 1,200 ovens, about 8,000 platforms for dwellings, artificial reservoirs, terraces for farming, and a rock quarry for construction materials.

3D overview of Labna palace at Puuc. Credit: Proyecto Arqueológico Regional de Bolonchén.
A ruin east of Kiuic built by the Maya in Puuc. Credit: Proyecto Arqueológico Regional de Bolonchén.

According to the researchers, a large number of circular ovens were likely used to heat sandstone in order to extract lime, an essential material used for mortar and to help soften maize. Before the LIDAR survey, archaeologists identified around 40 ovens. “Now, with lidar, we have a sample of over 1,230,” Ringle told Live Science.” They’re all over the place. And that indicates that it was a pretty big industry in the Puuc.” 

The area was also home to a burgeoning stoneworking industry. Most of the buildings identified by the researchers were masonry houses, suggesting that Puuc was highly prosperous. These included civic buildings known as early Puuc civic complexes, which involved several buildings with a plaza that were connected via elevated causeways.

LIDAR of houses at the Maya sites of Acambalam (B) and Kiuic (C). Credit: Ringle et al, PLOS ONE.
LIDAR of Middle Preclassic civic instructures. Credit: Ringle et. al, PLOS ONE.

The civic and religious structures erected had a distinctive style: stone facades embellished with mosaics and friezes and the prolific depiction of Chac, the Mayan rain god. 

One by one, after about AD 900, the Puuc cities were abandoned and swallowed up by the forest until they were“discovered” by later explorers and archaeologists.

Laser technology study reveals 1,000 monuments on ancient Scottish Isle

A cutting-edge archaeological laser scan (lidar) has revealed up to a thousand previously unknown monuments on the Scottish Island of Arran, which has been continuously inhabited since the early Neolithic period.

Temporary huts from the post-medieval period were identified for the first time. Image credits: Historic Environment Scotland.

Archaeologists have been interested in the Arran Island (which lies relatively close to Glasgow) ever since they discovered a remarkable concentration of early Neolithic Cairns — chambered funeral monuments consisting of a sizeable (usually stone) chamber and a structure of stones around it. The island also featured an important monastery and was involved in the Viking wars of the medieval age.

However, although the island is riddled with monuments and artifacts, actually mapping and discovering all of them remains challenging. Archaeological digs take a lot of time and are a delicate procedure so more and more, researchers are turning to remote sensing.

Arran Island as seen from above. Image credits: L. J. Cunningham.

Arran was scanned with Lidar — a remote sensing technology which uses the pulse from a laser to map distances with very high accuracy. It works something like this: a drone is flown above the area of interest. The position of the drone is measured very carefully and constantly monitored. The lidar equipment is on the drone, and it produces a detailed topographical map of the ground. But thankfully for archaeologists, Lidar goes even beyond that: it can reveal features which are indistinguishable from the ground level or with the naked eye.

The remains of a hut circle as seen with Lidar. Image credits: Historic Environment Scotland.

This is not nearly the first time Lidar has been used in archaeology. The approach has been successfully used multiple times (for instance to discover Maya or Roman features). However, archaeologists from Historic Environment Scotland (HES), who carried out the work, said this was the largest survey of this type ever undertaken in Scotland. It’s also a good example of how useful Lidar can really be in archaeology.

“As this technology becomes more widely available, we expect to find tens of thousands more ancient sites across the rest of Scotland – working at a pace that was unimaginable a few years ago,” says HES rapid archaeological mapping manager Dave Cowley.

He also added that the survey revealed far more ancient monuments than they knew about, allowing them to undertake a rapid survey within days, rather than wait months or years for a classic archaeological study — which probably wouldn’t have revealed as many features anyway.

Scientists want to make a 3D archive of the planet before it’s too late

Climate change is not only an existential threat to our livelihoods and that of countless other species with whom we share the world, but also threatens the relics of ancient cultures. Sea level rise, extreme weather events, wildfires, and desertification are some of the threats that could destroy both historic and contemporary sites, such as archeological sites, coastal cities, rainforests, and coral reefs. With this potential catastrophic future in mind, two daring scientists have hatched up an ambitious plan, not to avert this damage, but rather to conserve the memory of the world as we know it today for future generations by archiving it.

LiDAR map of Tikal. Credit: Luke Auld-Thomas and Marcello A. Canuto.

Archaeologist Chris Fisher and geographer Steve Leisz, both scientists at Colorado State University, are worried about the legacy they can leave to future generations. They think that we’re on a collision course with accelerated climate change and unless we have a record of the places that will be swept by the coming tempest, it will be as if they were never there.

This is why the two have started Earth Archive, a project whose ultimate goal is to create a 3D map of the entire world’s surface. But, how would that even be possible?

The key lies in a mapping technology known as light detection and ranging, or LiDAR.

LiDAR or 3D laser scanning was developed in the early 1960s for submarine detection from the air via aircraft. It works by generating a laser pulse train that is so fine that it can travel through the gaps of dense vegetation. By calculating the time it takes for the laser pulse to reflect back to its source, researchers can determine the elevation of the ground and create a 3D representation of any structure.

The technology is routinely used today to survey topography. While not too long ago it would take years to map an area, it now takes merely days.

Previously, LiDAR was used to reveal a huge medieval city in the Cambodian jungle, long-lost Roman roads, and over 60,000 breathtaking Mayan structures hidden away in the deep Amazon. NASA is also using LiDAR to map the Amazon rainforest’s canopy cover in order to estimate the effects of drought and other climate change effects.

Earth Archive would focus on the planet’s landmass, which covers roughly 29% of the surface. The most vulnerable places, such as the Amazon rainforest and coastal regions, would be prioritized.

There is real value in such an endeavor, but the challenges are immense. Funding is one of them. Speaking to The Guardian, Fisher says that the project would require around $10 million to map the Amazon over a period of three years. The entire world would take decades and perhaps over a billion dollars.

Getting permission to fly in the airspace of dozens of countries is not only logistically challenging but also politically challenging. For instance, Brazil President Jair Bolsonaro has time and time again proven that he is willing to undermine any scientific effort related to the climate.

But surmounting these obstacles is worth it, the scientists stress. It would be our ultimate gift to future generations, they say.

“We are going to lose a significant amount of both cultural patrimony – so archaeological sites and landscapes – but also ecological patrimony – plants and animals, entire landscapes, geology, hydrology,” Fisher told the Guardian. “We really have a limit time to record those things before the Earth fundamentally changes.”

You can learn more about Earth Archive in Chris Fisher’s TEDx talk below.

LiDAR or 3D map of Tikal. Credit: Luke Auld-Thomas and Marcello A. Canuto.

Scientists find over 60,000 new Maya structures (thanks to LIDAR)

LiDAR or 3D map of Tikal. Credit: Luke Auld-Thomas and Marcello A. Canuto.

LiDAR or 3D map of Tikal. Credit: Luke Auld-Thomas and Marcello A. Canuto.

More than 61,000 ancient Maya structures have been uncovered in Guatemala by a team comprised of only 18 researchers. Their secret? Laser tech known as LiDAR that can peer through the dense jungle and create a topographic map of thousands of square miles.

X-raying the jungle for ruins

Tikal (tee-KAL) is a ruined Maya city located in the northern Petén province of Guatemala, which used to be a very important and influential city during the heyday of the Maya Empire (1000 BCE-1500 CE).

The first archaeologists who arrived at Tikal during the late 19th century had to trek several days through the steamy jungle in order to reach the long-lost city.

Today, most of Tikal’s major buildings have been excavated, including structures such as the Plaza of Seven Temples, the Palace at the Central Acropolis and the Lost World complex. However, many other temples, buildings, and roads still lie hidden.

But thanks to modern technology, modern archaeologists don’t have to wander endlessly through the jungle in search for artifacts and hidden ruins.

To peek through the dense vegetation, an international team of researchers strapped LiDAR (light detection and ranging) technology on a low-flying aircraft which surveyed 2,100 square kilometers of terrain around Tikal.

Top: Tikal seen above the trees. Bottom: same view, this time stripped of vegetation by LiDAR. Credit: Luke Auld-Thomas and Marcello A. Canuto/PACUNAM.

Top: Tikal seen above the trees. Bottom: same view, this time stripped of vegetation by LiDAR. Credit: Luke Auld-Thomas and Marcello A. Canuto/PACUNAM.

LiDAR or 3D laser scanning was developed in the early 1960s for submarine detection from an aircraft. It works by generating a laser pulse train which can travel through the gaps of dense vegetation. By calculating the time it takes for the laser pulse to reflect back to its source, researchers can determine the elevation of the ground. This way, archaeologists can identify human-made features on the ground, such as walls, roads, and buildings.

According to Marcello A. Canuto, director of the Middle American Research Institute at Tulane, and Francisco Estrada-Belli, a research assistant professor and director of the Holmul Archaeological Project, the team was able to identify more than 60,000 structures in the Petén forest of Guatemala.

LiDAR map of another Maya settlements north of the ancient city of Tikal. Creidt: Luke Auld-Thomas/PACUNAM.

LiDAR map of another Maya settlements north of the ancient city of Tikal. Creidt: Luke Auld-Thomas/PACUNAM.

The breathtaking video below offers a glimpse of the power of LiDAR and the intricate Mayan structures hidden beneath the canopies.

The new findings suggest that the Mayans used more advanced agriculture practices than previously thought. Roads linking many of the urban centers of the time also suggest that Mayan cities were more closely connected than earlier thought.

“It seems clear now that the ancient Maya transformed their landscape on a grand scale in order to render it more agriculturally productive,” said Canuto in a statement. “As a result, it seems likely that this region was much more densely populated than what we have traditionally thought.”

“Seen as a whole, terraces and irrigation channels, reservoirs, fortifications and causeways reveal an astonishing amount of land modification done by the Maya over their entire landscape on a scale previously unimaginable,” Estrada-Belli added.



Artist impression of how the laser-fluorescence instrument could operate on Mars. Credit: NASA

New laser tech could be the life-sniffing ‘nose’ for NASA’s next Mars rover

Artist impression of how the laser-fluorescence instrument could operate on Mars. Credit: NASA

Artist impression of how the laser-fluorescence instrument could operate on Mars. Credit: NASA

One of the biggest concerns NASA scientists looking for alien life on Mars have is that they might one day find biological signatures — only to later find these were actually contaminants brought from Earth. An upgrade to a laser radar called LIDAR, typically used to monitor air quality or map large areas, could solve this concern and make investigations a lot more efficient, say NASA scientists.

A light nose

The instrument is called  Bio-Indicator Lidar Instrument, or BILI. Branimir Blagojevic, now a NASA technologist at the Goddard Space Flight Center in Greenbelt, used to work for the company that first made the device. At NASA, Blagojevic used his experience and skills to turn the technology into a working prototype that shows that the same instruments used to monitor biohazards in public places could be effective at detecting organic biosignatures on Mars, too.

LIDAR is a remote sensing instrument that is very similar in working principle to radar. However, instead of radio waves, LIDAR uses light shone by lasers to measure distances from a target, but also determine the composition of particles in the air.

BILI is essentially a fluorescence-based lidar that can detect chemicals based on their fluorescent emissions. Fluorescence-based sensing instruments have been widely employed by NASA in its climate research, but soon the space agency will also use it in planetary studies. “If the agency develops it, it will be the first of a kind,” Blagojevic said.

Because it can detect small levels of complex molecules in real time from a distance of several hundred meters, BILI could serve as the nose of NASA’s next rover mission, planned for 2020. The instrument can be used to scan the bio-signatures in plumes above recurring slopes which are very challenging to travel for a rover. It could also be targeted on ground-level aerosols with no risk of sample contamination.

For now, Blagojevic envisions BILI positioned on a rover’s mast. Initially, the instrument first scans for dust plumes, then, once detected, the command is issued for two ultraviolet lasers to shine light pulses at the dust. The illumination causes the dust clouds to resonate or fluoresce. It’s then only a matter of analyzing this signal and comparing it with known signatures from a database to detect organic particles. The same analysis also reveals the particles’ size.

“If the bio-signatures are there, it could be detected in the dust,” Blagojevic said in a statement for the press.

“This makes our instrument an excellent complementary organic-detection instrument, which we could use in tandem with more sensitive, point sensor-type mass spectrometers that can only measure a small amount of material at once,” Blagojevic said. “BILI’s measurements do not require consumables other than electrical power and can be conducted quickly over a broad area. This is a survey instrument, with a nose for certain molecules.”

Why stop at a rover, though? Indeed, NASA has plans to mount BILI or a later version onto spacecraft. NASA could then significantly increase its odds of detecting biosignatures in the solar system.

Next for Blagojevic and colleagues is to refine their design. The goal is to make BILI smaller, more rugged, and more sensitive to a broad range of organic particles.

Laser technology reveals huge medieval cities hidden in Cambodian jungle

Who needs Indiana Jones when you’ve got technology? A new study using laser imaging has revealed several impressive cities hidden in the Cambodian jungle.

Cambodian Archaeological Lidar Initiative

Doing archaeology in vegetation-rich areas can be a big hassle, and even impossible. Cambodia’s jungle is big, rugged and arduous even to access, let alone do archaeological studies in it. But then again, who needs to get their hands dirty in the jungle, when you can simply fly above it?

Several organizations have launched the Cambodian Archaeological Lidar Initiative, which aims to use remote airborne laser scanners (a technology called LIDAR) to visualize undiscovered archaeological sites. The same technology has been proven many times in the past, including for finding some forgotten Roman Roads.


Cambodian Archaeological Lidar Initiative

LIDAR didn’t disappoint this time either, and scientists found several settlements close to the ancient temple city of Angkor Wat in the north-west of the country, dated from approximately 900-1400 years ago. Some of the cities are so big, they’re comparable in size to Cambodia’s current capital, Phnom Penh.

“We have entire cities discovered beneath the forest that no one knew were there,” archaeologist Damian Evans, who carried out the research, told The Guardian.

“These airborne laser discoveries mark the greatest advance in the past 50 or even 100 years of our knowledge of Angkorian civilisation,” archaeologist Michael Coe from Yale University, who wasn’t involved in the research, told The Guardian.

Cambodian Archaeological Lidar Initiative

The technique uses a helicopter to fly above the ground. The helicopter is fitted with an airborne laser scanner which sends 16 laser pulses which measure each square metre of ground, revealing the height of the ground. The helicopter flies at a constant speed, highlighting where rising structures stand.

The good thing about this technique is that it clearly shows structures which would otherwise be very difficult to spot. You may be walking right in the middle of a former city and not even realize it.

“It turned out we’d been walking and flying right over the top of this stuff for 10 years and not even noticing it because of the vegetation,” said Evans. “What we had was basically a scatter of disconnected points on the map denoting temple sites. Now it’s like having a detailed street map of the entire city.”

The LIDAR scans revealed roads, canals, furnaces, and even beer gardens. This is a bigger finding than even the more optimistic archaeologists were expected. Remote sensing is changing archaeology, and for starters – it may revolutionize what we know about Cambodian civilizations.

UK Archaeologists find 5 long-lost Roman roads

British archaeologists have uncovered five Roman roads built over 2,000 years ago using a technology called LIDAR – a mix between LASER and RADAR. The roads were used by Roman settlers in the 1st century AD and the discovery will allow researchers to better understand how areas in today’s UK were conquered and how the road infrastructure was developed.

UK Environment Agency.

Previously in Lancashire we only had aerial photographs from the 1940s and 1960s to go on, but with photographs features only show up after a drought and we don’t get many of those,” said one of the team, David Ratledge from the UK Environmental Agency. “With Lidar, once you know what to look for, it’s blindingly obvious – you just know you’ve found a road… It’s been revolutionary.”

Since 1998 the Environment Agency has used lasers to scan and map the English landscape from above. They’ve done this mostly for flood modelling and tracking changing coastlines, but every once in a while, they find something that’s of other interest. This time, the LIDAR data proved extremely interesting for archaeologists seeking to map Roman roads that have been ‘lost’, some for thousands of years. Interestingly enough, these roads show how Roman’s legions advanced through the country and conquered parts of the country.

“These were the county’s most important Roman sites so good communications between them must have been essential,” Ratledge continued. “Rather than following the Ordnance Survey route, it took a very sensible and economical route via Longridge and Inglewhite to Catterall, near Garstang. Here it joined the main Roman road from the south heading to Lancaster.”

First invented in the 1960s, Lidar technology makes use of ultraviolet, visible, or near infrared light to map objects in a very high resolution. The British government has been very inspired in making this data available to the public, so not only other researchers but also amateurs can have a go at finding hidden landscapes. Although LIDAR can’t truly see underground, it can spot subtle indentations in the landscape. In the case of a road or a former foundation, the soil has different parameters in terms of cohesion, chemical make-up and compactness. After 2,000 years, this isn’t visible with the naked eye, but it is visible with LIDAR.

So far, five roads have been uncovered but there’s certainly many more roads and infrastructure elements awaiting to be discovered. The Environment Agency is making all 11 terabytes of its LIDAR surveys available as open data as part of the #OpenDefra initiative. These data are available for everyone to use for free through the new Survey Open Data portal.