LiDAR: The Archaeologist's Mapping Tool of Choice
Recently, an article came through my Apple News feed, headlined "Missing Killerton mansion may have been found by LiDAR laser scans", from the DailyMail by Tim Collins (06/20/2017). This was interesting timing. Right around then, GreenValley International (GVI) received an inquiry from our Iraqi distributor about local government interests in utilizing GVI LiDAR mapping systems for archaeological projects. Only several days later, we were contacted by our partner, Velodyne LiDAR for an opportunity to potentially participate in an upcoming History Channel program involving using LiDAR for archaeology research. We had always known LiDAR could be a great tool for archaeology but until these recent inquiries we did not realize how important LiDAR had become for modern archaeology.
From revealing ever more hidden sites from the massive Mayan City of Caracol to discovering vast medieval cities in the jungle of Cambodia, to the recent potential finding of the Killerton Mansion, LiDAR has made fantastic contributions to archaeology. As said by Dr. Michael Coe, emeritus professor of anthropology at Yale University and one of the world's pre-eminent archaeologists specializing in Angkor and Khmer civilizations:
"I think that these airborne laser discoveries mark the greatest advance in the past 50 or even 100 years of our knowledge of Angkorian civilization."(Revealed: Cambodia's vast medieval cities hidden beneath the jungle)
Watch this YouTube video in which archaeologist Dr. Chris Fischer and his colleague Dr. Stephen Leisz from Colorado State University so energetically talked about their exciting discovery and mapping of a major but previously unknown city of the Purepecha empire using aerial lidar scanning (ALS) in west Mexico while surveying the ruins of Angamuco.
LiDAR is Great for Discovering Previously Unknown Archaeology Sites
ALS is capable of producing very high-resolution data of the earth surface (DEM, Digital Elevation Model) for a large area very quickly, revealing details otherwise difficult to see and helping to connect earthwork features otherwise might have been thought to be isolated.
What makes LiDAR really useful and uniquely suited for archaeology, however, is its ability to "penetrate" or "see through" the canopy and map the earth surface beneath the vegetation. If there are sufficient gaps in the canopy as shown in the photo below, LiDAR can map the terrain, potentially in very high resolution.
Besides new discoveries, LiDAR can also be used for scanning and documenting known historical/heritage sites, buildings and features for preservation or furthering ongoing research.
This has been in practice for decades, especially in Europe. Thanks to the recent development in technology, it is now possible to fuse a detailed 3D model derived from LiDAR point cloud with high resolution high dynamic range imagery (photos) to create amazingly realistic virtual reconstruction of these cultural treasures.
More Options are Available to Archaeology and Cost is No Longer a Barrier
Getting new technology to the masses takes time. In the past, acquiring LiDAR data for most users required hiring specialized vendors, especially for ALS collection. The service cost quite a significant amount, easily in many tens of thousands of dollars for a single collection, which could be prohibitive to many. In addition to cost, scheduling sometimes could be challenging. Fortunately, that's changing rapidly in recent years.
Today, there are many UAV-based LiDAR systems available in the commercial market, such as the GVI LiAir Series (image below). Depending on the system configuration, the cost ranges from $50,000 to $200,000 and above. Packed with the latest LiDAR sensor capable of sending out several hundreds of thousands of pulses per second, very high precision GPS and IMU, UAV LiDAR is especially suited for archaeological projects given their collection size and requirement on high point density. These systems are easy to operate and can be taken to just about any project sites. Owning a UAV LiDAR system would provide the extraordinary operational flexibility that could be very beneficial to many in the archaeology community.
LiAir and LiBackpack from GreenValley International
GreenValley International (GVI) offers a range of UAV LiDAR systems all the way to the survey grade LiAir Pro. We will soon have a new product out, the LiAir Standard. Equipped with the Velodyne VLP-16, a powerful sensor with 16 laser channels, 100-m scanning range, and 300,000 pts/sec scanning rate, LiAir Standard is a perfect choice for archaeologists. What makes it even better is the $35,000 price tag (not including the UAV)!
For more information on LiAir Standard and its release date, please send your inquiry to firstname.lastname@example.org.
GVI also offers the unique LiBackpack, a mobile LiDAR system based on SLAM technology (simultaneous localization and mapping) that enables continuous LiDAR data collection without the need for GPS and expensive IMU. It is a great option for collecting LiDAR data in situations where GPS signal is not available such as under heavy canopy and inside a cave or building.
Collecting high-quality point cloud is just the first step obviously. The data still needs to be processed and converted into meaningful and useful information. GVI's flagship LiDAR point cloud post-processing software, LiDAR360, will get the job done. From classifying terrain to extracting forestry metrics, LiDAR360 offers a suite of powerful tools that allow users to efficiently work with the point cloud data collected and quickly produce important information right there on site.
LiDAR is no doubt already a very important tool for archaeology. With the costs for LiDAR hardware and software continue to go down while their capability and functionality continue to improve, as some experts said,
LiDAR will become the archaeologist's map tool of choice.