Fort Matanzas National Monument Digital Documentation Project: Utilizing Terrestrial Lidar For The Understanding Of Structural Integrity Concerns For Coastal Forts And Coquina Structures (Cesu,National Park Service)
Fort Matanzas, described as a fortification that was the “guardian to St. Augustine’s backdoor” (Arana 1978), is a National Park Service site locale that is facing issues of damage and decay due to its age and continual exposure to natural environmental and anthropogenic factors. The construction has persistently deteriorated and its structure and materials require constant maintenance and restoration. The weight of the coquina stone and erosion of foundational support have led to significant, uneven settling or sinking of the foundation into the sandy soil. This condition is exacerbated by the wetness of the soil caused by annual rains and the Fort’s placement within meters of the river’s edge. The most substantial weight of the structure is concentrated below its vertical exterior walls causing the perimeter of the building to sink deeper into the soil than the center. This circumstance, along with the weakening and deterioration of the subsurface foundation, has caused the walls of the structure to bow and ultimately crack at its weakest points.
In addition to the foundational breakdown and wall fractures, other structural problems are also of concern. The coquina stone used in the fort’s construction is a partially consolidated sedimentary rock composed of compressed seashell or coral and, because of continual exposure to natural elements, some of the stone is dissolving. The joints bonding the coquina blocks together were originally made with lime-based mortar that, over time, has deteriorated and decomposed from weathering and moisture intrusion. Previous restoration efforts to repair these joints often utilized materials such as Portland cement, a material that is now known to cause cracking of the stone and fissuring of the joints.
In September 2012, the University of South Florida (USF) Alliance for Integrated Spatial Technologies (AIST), undertook a survey utilizing terrestrial laser scanning (TLS), survey-grade global positioning systems (GPS), GPS imagery, and photogrammetric and other forms of standard and advanced photo imagery. Using these non-contact, non-destructive techniques, the entirety of the fort and its surrounding terrain features were captured in high resolution details (structural aspects at +/- 2mm), to provide a holistic landscape context documentation for planners and managers. These data were processed and brought together with existing digital legacy data detailing environmental and cultural historical aspects and remotely sensed aerial data such as aerial imagery and LiDAR. These data sets were then combined using a geographic information systems (GIS) approach with outputs consisting of a geodatabase structure, as well as user-friendly and interpretive deliverables including virtual globe (Google Earth) modeling, and 3D fly-through videos and models. All 3D work performed is supportive of computer automated drawing (CAD) output, and data are archival in formats to allow for use in long-term monitoring and management assessment at the site.
Scholar Commons Citation
Collins, Lori D.; Doering, Travis F.; and Gonzalez, Jorge, "Fort Matanzas National Monument Digital Documentation Project:
Utilizing Terrestrial Lidar For The Understanding Of Structural Integrity Concerns For Coastal Forts And Coquina Structures (Cesu,National Park Service)" (2013). Digital Heritage and Humanities Collections Faculty and Staff Publications. 3.