Established in 1864, Chalmette National Cemetery serves as the final resting place for soldiers who died in Louisiana during the Civil War. Its coastal location makes it vulnerable to flooding and erosion resulting from hurricanes and tropical storms, which damage grave markers.
The National Park Service (NPS), which manages the cemetery, sought to inventory over 15,000 grave markers within the cemetery and assess the condition of each headstone to identify those needing resetting or replacement. NPS retained our archaeological team to inventory and assess all grave markers. They tasked us with mapping, photographing, and recording the attributes of the grave markers, transcribing text on headstones, and assessing the condition of each grave marker.
Given the scale of the mapping task, we began by flying NPS-approved drone flights above and below the tree canopy to capture high-resolution images. We used these images to develop a three-dimensional model of the entire cemetery using structure-from-motion photogrammetry. We also created a high-resolution orthomosaic—a detailed, geometrically corrected aerial map created by stitching together overlapping images.
Our archaeologists in the field used the orthomosaic, which was georeferenced using survey-grade GPS, to map grave marker locations. Using a paperless workflow, we assessed the condition of each grave marker based on legibility, damage, cleanliness, and alignment. We consolidated data in an interactive ArcGIS dashboard, which allowed NPS and project leadership to monitor survey results in real-time. The use of drone-based mapping and digital tools allowed us to complete the survey in just four weeks.
With detailed information about the condition of grave markers, NPS can better manage vulnerable sites and make informed decisions for long-term stewardship. They have already begun to use data to determine which areas of the cemetery need realignment and which headstones need replacement.
Inspired by our work at Chalmette, we developed an AI-assisted text recognition tool to streamline headstone transcription for future projects. This tool will greatly improve the accuracy and speed of the work compared to manual methods.
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