Preserving cultural heritage is vital for maintaining a tangible link to our shared history, allowing future generations to experience and learn from those who came before us. Advances in remote sensing technology offer new tools for conservationists, with hyperspectral imaging emerging as one of the most powerful non-invasive techniques for preservation.

Benefits of Satellite Remote Sensing

Space-based remote sensing can scan large, inaccessible areas, making it invaluable for discovering and continuously monitoring heritage sites. High-resolution satellite imagery helps identify buried structures, ancient pathways, and environmental shifts that indicate human activity. This technology has proven crucial in uncovering archaeological sites in remote locations and monitoring existing sites for changes or threats.

For example, Sarah Parcak, an anthropology professor at the University of Alabama, has utilised satellite imagery to uncover over 3,000 ancient settlements, dozens of pyramids, and over a thousand lost tombs in Egypt. This approach provides a non-intrusive way to survey vast areas, enhancing archaeological research and site preservation.

National Geographic Graphics. Sources: Sarah Parcak and Gregory Mumford, University of Alabama at Birmingham; DigitalGlobe.

The Hyperspectral Advantage

Unlike traditional imaging, which records data in three colour bands (red, green, and blue), hyperspectral imaging captures hundreds of electromagnetic spectral bands. Each pixel in the resulting 3D data cube contains rich spectral information, allowing for highly detailed material analysis and detection of hidden features. 

A hyperspectral data cube. Source: NIST

Until recently, hyperspectral imaging was primarily limited to government space missions. However, technological advancements and sensor miniaturisation have enabled private startups like Pixxel to offer a broader range of hyperspectral imagery datasets, expanding their accessibility and application in cultural heritage preservation.

Applications of Hyperspectral Imaging in Heritage Preservation

The advantages of hyperspectral imaging—the ability to noninvasively detect underlying details, identify materials, and monitor degradation—unlock great potential for applications in cultural heritage preservation.

1.Detection of Subsurface Features: Hyperspectral imaging can detect buried or hidden structures by analysing spectral data that reflect differences in soil composition, moisture content, and vegetation patterns. This capability makes it a powerful tool for discovering archaeological remains and monitoring site changes.

2.Monitoring the Degradation of Historical Landscapes: Outdoor heritage sites are vulnerable to natural degradation from erosion, vegetation overgrowth, and climate change. Satellite-based hyperspectral imagery allows researchers to monitor these changes over time, offering a non-invasive way to assess site health and inform conservation strategies.

3.Uncovering Lost or Overgrown Cultural Landscapes: Dense vegetation often covers forgotten sites, making them difficult to detect with standard imaging. Hyperspectral imaging can penetrate vegetation and analyse spectral differences, revealing buried ruins or altered soil compositions that suggest hidden cultural features. For example, in 2002, the IKONOS satellite captured multispectral images of a bajo (low-lying areas where rainwater accumulates) in Guatemala, revealing remnants of ancient Maya irrigation structures. While this discovery was made using multispectral sensors, hyperspectral imaging could provide even deeper insights into similar landscapes.

The bajo detected in Guatemala through the IKONOS satellite (Source: NASA Earth Observatory).

4.Documenting and Preserving Large-Scale Monuments: Due to their scale, large monuments such as castles, pyramids, and temples can be difficult to assess from the ground. Hyperspectral imagery can map these structures comprehensively, capturing visible and non-visible details crucial for long-term preservation. For instance, the Italian Space Agency used COSMO-SkyMed satellites to monitor the ancient Roman city of Pompeii. Hyperspectral data revealed the mineral composition of critical structures and helped safeguard ruins from soil movements and adverse weather conditions.

Ancient walls in Pompeii with volcano Vesuvius in the background. Source- dbvirago; iStock photo

5.Preventing Looting and Illegal Excavation: Hyperspectral imaging can protect cultural heritage from looting and illegal excavation by monitoring disturbances in the landscape that may indicate unauthorised digging or damage.

Future Challenges and Prospects

Hyperspectral imaging has significant potential for preserving our art and heritage but has its challenges. A primary concern is data availability, as comprehensive hyperspectral datasets remain scarce, particularly in remote or less-monitored areas. Many historical artefacts may have yet to be imaged, resulting in insufficient data for detailed analysis.

Additionally, the vast volume of spectral data generated requires specialised algorithms and powerful computing for processing, which can make interpretation slow and costly. Environmental factors, such as cloudy skies and varying light conditions, can introduce noise that compromises data quality, necessitating careful planning and advanced correction techniques for accurate results. The high costs associated with hyperspectral imaging equipment further restrict its widespread use.

However, companies like Pixxel are advancing innovation with advanced hyperspectral imaging satellites that provide clear images, accurate spatial details, and frequent updates. The increased accessibility and affordability of hyperspectral imagery will open up exciting new possibilities by revealing unknown information about heritage sites.

Connect with the Pixxel team today to explore how cutting-edge hyperspectral imaging can benefit cultural heritage conservation efforts.

FAQs

1.What is hyperspectral imaging?

Hyperspectral imaging captures images across hundreds of spectral bands, allowing detailed analysis of materials and features.

2.How does hyperspectral imaging differ from traditional imaging?

Hyperspectral imaging captures hundreds of wavelengths, providing detailed spectral data, whereas traditional imaging typically records in just three colour bands (red, green, and blue).

3.How does hyperspectral imaging benefit cultural heritage preservation?

Hyperspectral imaging uncovers hidden details, identifies materials, and monitors degradation non-invasively.

4.What are the challenges of using hyperspectral imaging?

Critical challenges of hyperspectral imaging include data availability, high costs, and the need for specialised processing techniques.

5.How is hyperspectral imaging used in archaeology?

Hyperspectral imaging can detect buried structures, monitor environmental changes, and help document large monuments.