For archaeologists, an ever-changing physical and political landscape poses challenges to identifying, assessing and preserving ancient sites. It’s a race against the clock given shrinking budgets, climate change and human intervention. Recently, however, satellite imagery has taken on an important role in the discovery process with not only the help of high resolution imagery itself but specifically the near-infrared band commercially available on WorldView-2 .
The need to understand soil composition
Many ancient landscapes are obscured by modern development, making it difficult and, at times, impossible to locate important archaeological features. Surface vegetation and soil composition hold a key to what lies beneath. The presence of mud brick, for example, a common and ancient building material, has a direct effect on the soil moisture and vegetation above as it degrades.
“The high-resolution and near-infrared imagery generated by satellites like WorldView-2 detects those subtle changes to the soils where magnetometers and other traditional survey methods do not,” explains Dr. Sarah Parcak, Associate Professor of Anthropology at the University of Alabama at Birmingham. “It enhances our ability to pinpoint areas of interest that will likely require further survey and potential excavation.”
How will WorldView-3 enhance the industry?
High-resolution satellite imagery, like that from DigitalGlobe’s constellation of five satellites, currently helps the archaeological industry with mapping, cadastral, elevation data, feature extraction and soil classification in a cost-effective manner. Now with the launch of Worldview-3 just weeks away, the archaeological community is even more excited for the capability of Short-Wave Infrared (SWIR) – adding spectral coverage to the invisible range to help identify things like minerals and specific vegetation. This enhancement will allow archaeologists to be able to detect sites more easily and to ask more relevant questions about those ancient landscapes.
But don’t take it from us; hear Dr. Sarah Parcak speak about what the launch of WorldView-3 means to her and how it will be a “game-changer” for archaeologists everywhere!
By Josh Winer, Sales Manager at DigitalGlobe; Nigel Sizer, Global Director of World Resource Institute’s Forests Program; James Anderson, Forests Communications Officer at World Resource Institute
One of the most devastating threats to the environment, economy, and human health in Indonesia comes in the form of fire. Forest and bush fires, often associated with agricultural expansion and land conflict, can release a toxic haze that shuts down cities, obscures the skies, and sickens tens of thousands of people. But a lack of good information on where the fires are occurring and why has been a stumbling block to preventing them.
Today, the World Resources Institute (WRI), DigitalGlobe, the Indonesian government, Google, Esri, and a host of other partners launched Global Forest Watch Fires, an online platform for monitoring and responding to forest and land fires in Southeast Asia. It features near real-time satellite images from DigitalGlobe, fire alerts from NASA, an SMS (phone-texting) alert system, mapping of burn scars from Google Earth Engine, wind direction and air quality data and land-use and concession maps.
At the core of the platform is a new partnership between WRI and DigitalGlobe, which will bring the power of high-resolution satellite images to bear on the fires. As part of its Seeing a Better World™ Program, DigitalGlobe has tasked its five satellites to provide near real-time images of the fires at a remarkable 50 centimeter resolution, which is sharp enough to see the home plate on a baseball diamond. DigitalGlobe’s sixth satellite – WorldView-3 – launching in August will offer even finer 31 centimeter resolution and provide additional insights about the health of plants with a new shortwave infrared sensor that can help identify ground features through smoke, fog and haze.
Access to this super-spectral, very high resolution satellite imagery provides rare insight into the fires. At lower resolutions (most freely available satellite images are no better than 30 meter resolution), it is difficult to tell where the fires have burned, how they may have started, or even what type of land cover is affected. With DigitalGlobe’s imagery, you can see down to the individual tree level and even identify species. DigitalGlobe imagery is processed as color-infrared, enabling WRI to quickly distinguish between healthy and dead vegetation, draw burn area boundaries, and detect burn scars in order to assign accountability to the fires.
Below are some preliminary observations on how DigitalGlobe imagery can be used to track the Southeast Asia fires and prevent future burning.
1. Fires can now be precisely pinpointed in time and space and the imagery can serve as powerful evidence of possible wrongdoing
Lat: 2.026 / Long: 100.453
A quick survey of NASA’s Active Fire Data shows widespread fire alerts on the island of Sumatra, Indonesia, and particularly in the province of Riau. WRI analysis indicates that Riau accounts for over half the fire alerts in Indonesia and over 80 percent of the fires in Sumatra. DigitalGlobe’s high-resolution imagery confirms the presence of fires in the locations of NASA fire alerts, and in some cases, you can even see the flames. The fires are clearly causing the haze that has afflicted the region. The image above shows huge smoke plumes rising from relatively small fires in Riau.
This high-resolution imagery provides the sort of clear visual evidence that is needed for government to commit law enforcement resources to a specific location, or for companies to weigh whether or not their suppliers are involved in burning.
2. The impact of each fire can be precisely measured and mapped
Note: The image above is rendered in “false color”, which displays healthy vegetation as pink. Image location: Lat: -0.12331 / Long: 101.5838
Until now, it has been difficult to gauge the exact extent and impact of the fires. But with high-resolution imagery, it is possible to map burn scars with great accuracy and determine the extent of land affected. This could be used in combination with vegetation data to calculate damage from individual fires, and possibly also greenhouse gas emissions from the blazes.
The images above (which have been rendered in “false color” to make vegetation change clearer) show two DigitalGlobe satellite images of a plot of land from June 21, 2014 and July 21, 2014. These images reveal that even when an active fire is not present in an image, a fire’s age can be estimated. The “before” image shows what appears to be natural forest cover (in pink), while the “after image” shows a large burn-scar and the presence of young oil palms nearby.
Previous WRI analysis has found that roughly half of all NASA fire alerts occur in concessions granted for oil palm, timber, and pulpwood plantations.
3. Many fires spread unintentionally causing significant damage, often these fires are related to conflict over land
Lat: 2.026 / Long: 100.453
Several images have shown areas where the fires are burning established oil palm or woodpulp plantations, rather than natural forest or scrubland. This may indicate that some fires are accidental, or spread out of control. Either way, the fires result in economic damage for the owners.
Some of these fires are likely the result of land conflict. In areas with poor land tenure or spatial planning, community land may be allocated for large-scale agricultural development, and communities may use fire to deliberately damage or claim land controlled by larger companies. Further investigation into this complex issue is needed.
4. The fires vary greatly in shape and size
Lat: 2.026 / Long: 100.453
The burn scars detected through the DigitalGlobe images come in a wide variety of different shapes and sizes, which may indicate they are set by different actors for various purposes. Some fires burn across large areas, perhaps indicating large agricultural operations or fires that have burned out of control. Other fires are small, possibly indicating small holders or accidental fires.
As the dry season continues in Southeast Asia —perhaps exacerbated by an El Niño year— the risk of new fires will remain high, perhaps spiking again to the severe levels seen in June 2013 or March 2014. DigitalGlobe and WRI will continue to provide new images of the fires as they occur on the GFW-Fires platform. These images can help provide the insight needed for government agencies, businesses, and civil society to combat these fires. Soon, you will be able to help too through DigitalGlobe’s Tomnod crowdsourcing platform by reviewing the satellite imagery and classifying areas that have burned. So check back soon and join us to help combat fires for clearer skies over Southeast Asia.
DigitalGlobe is hosting a Twitter chat on July 9th, a week prior to attending the ESRI User Conference in San Diego. This #DGchat will feature Luke Barrington (@lukeinusa), Senior Manager of Crowdsourcing, as we discuss:
Lessons learned from recent campaigns
Disaster relief efforts around the globe
Use cases and future applications of crowdsourcing
Geospatial Big Data & WorldView-3
Join the Twitter chat by asking questions and contributing to the dialogue about analytics, GIS and the commercial satellite industry using #DGchat. By adding #DGchat to the end of each tweet, you signify your involvement in the conversation. To easily follow the chat, log in to Twitter via TweetChat and enter #DGchat as the hashtag to follow. It will then automatically show the conversation and add the hashtag to each tweet posted.
Not available for the chat? Tweet your questions to @DigitalGlobe in advance, using #DGchat. If you aren’t on Twitter, but are interested in asking a question, feel free to post questions on the DigitalGlobe Facebook page or send questions in an e-mail to firstname.lastname@example.org.