Mapping the past: How digital elevation models revive lost heritage

Digital elevation models contain finely gridded elevation values and can be derived from sources such as satellite data or LiDAR. These models, while originally designed for scientific analysis, have proven to be powerful tools for storytelling in the humanities. The study demonstrates this by mapping the Linge River region in the Netherlands using DEMs and overlaying them with an 18th-century municipal map.

A new study has illuminated how digital terrain data, modern mapping techniques, and centuries-old cartography can work together to recover lost or obscured narratives of cultural heritage. Titled "Digital elevation models, old maps, and cultural heritage - geospatial assets for the digital humanities," and published in Frontiers in Communication, the paper offers a landmark exploration of how tools typically associated with earth sciences - Digital Elevation Models (DEMs), LiDAR, and Geographic Information Systems (GIS) - can serve the digital humanities by helping us visualize, preserve, and analyze human impacts on the landscape over centuries.

The study focuses on the Dutch landscape, renowned for its intricate relationship with water management. It investigates how different types of DEMs, Digital Surface Models (DSMs), Digital Terrain Models (DTMs), and Relative Elevation Models (REMs), can be used in conjunction with historical maps to reveal how humans shaped, and continue to shape, their physical environment. The results show that subtle elevation differences, imperceptible to the eye but critical to historical infrastructure like dikes and fortresses, are preserved in today’s terrain and offer new insights into the region’s cultural memory.

How can elevation data help visualize the past and inform cultural heritage?

Digital elevation models contain finely gridded elevation values and can be derived from sources such as satellite data or LiDAR. These models, while originally designed for scientific analysis, have proven to be powerful tools for storytelling in the humanities. The study demonstrates this by mapping the Linge River region in the Netherlands using DEMs and overlaying them with an 18th-century municipal map.

The results are visually and analytically striking. While DSMs capture everything above the ground - trees, rooftops, building - DTMs reveal only the earth's bare surface. REMs, a more specialized format, show elevation relative to specific features like rivers, thus accentuating minor changes and helping identify legacy features such as ancient fortresses, buried drainage channels, and elevated paths used for centuries. By comparing the old map with DEM-based renderings, the researcher highlighted the extraordinary continuity of Dutch water management infrastructure. Dikes built 300 years ago remain standing and functionally unchanged, clearly visible in both historical and modern representations.

This mapping process uncovered not just historical features, but also cultural expressions embedded in the terrain such as an old star-shaped landfill turned picnic area, now invisible from the ground but identifiable in the elevation data. These features, and the cultural meaning they carry, are revealed through precise digital cartography.

What strengths and weaknesses do digital elevation models bring to cultural heritage research?

Each DEM type serves distinct purposes in visualizing cultural heritage. DSMs are rich in surface detail and immediately recognizable to local residents because they reflect the current environment, including vegetation and human structures. However, this detail often overshadows terrain subtleties relevant to historical interpretation.

DTMs, by contrast, strip the landscape down to its geomorphological essence. In the Dutch context, this reveals essential heritage elements like man-made drainage systems, the sediment-based elevation of towns such as Asperen, and the historic Dief Dike. By using a limited elevation range and carefully chosen color schemes, DTMs can highlight the minimal but critical elevation variations that shaped settlement patterns and defensive infrastructure. Yet DTMs lack cognitive anchors, making them less intuitive for casual observers unfamiliar with geospatial analysis.

REMs are best suited for mapping natural river systems or loosely managed landscapes, where subtle elevation changes inform geomorphic analysis. In the highly regulated Dutch context, REMs offered fewer advantages over simpler DTMs. The research concludes that while REMs are computationally intensive and less impactful in tightly managed terrains, they remain valuable for exploring features like sediment distribution or ancient river migration patterns.

Through rigorous visual comparison, the researcher found that a combination of DSMs (for recognizable structures) and DTMs (for historical terrain analysis) delivered the best results for both scholarly inquiry and public engagement. Maps that merged the shadow of a DSM with the stripped-down clarity of a DTM were not only esthetically pleasing but also effective in communicating complex spatial information.

How do maps foster public engagement and interpretation of cultural memory?

To test the maps’ communicative power, the researcher presented the outputs to four residents of Asperen. The simple question posed - “What do you think?” - elicited rich qualitative feedback. Residents immediately recognized familiar structures in the DSMs, including buildings and tree canopies. In contrast, DTMs prompted reflection on less visible aspects of the landscape, such as elevation-linked settlement safety.

Participants expressed a strong emotional connection to the dikes, interpreting the high terrain as symbols of protection and resilience. Regardless of color scheme - whether red denoted danger or safety - the sense of security conveyed by elevation persisted. The maps were described as thought-provoking and aesthetically pleasing, with many viewers favoring color palettes that matched historical maps for their elegance and sense of continuity.

Participants also contributed insights about features not documented in the old map, such as the aforementioned landfill-picnic area. These interactions confirmed that DEMs are not just technical tools; they can also function as boundary objects that spark dialogue, reinforce collective memory, and prompt new historical inquiries.

The study positions the mapping process itself as a form of critical inquiry. Cartographic design choices like color, scale, and focus shape what is seen, felt, and understood. In flat landscapes like the Netherlands, where elevation differences are minimal but consequential, those choices determine whether a dike or floodplain is interpreted as historical artifact or invisible background.

Beyond its contribution to Dutch heritage studies, the methodology offers scalable value. The study used freely available LiDAR data and open-source QGIS software, making the approach globally replicable. Whether in ancient Maya cities obscured by jungle or forgotten Roman roads beneath modern towns, the same spatial logic applies: digital elevation can expose what time and vegetation have hidden.