The primary 3D technology employed by the archaeological team at the WLCC for surface documentation is the Breuckmann OptoTOP-HE structured-light scanning system. Using fast light projection and a high resolution camera, the structured-light scanner can capture surface topography with a very high degree of accuracy and point resolution. The Breuckmann scanner also collects color photographic information in addition to three-dimensional point cloud data, providing complete 3D documentation of the target object.
To record discrete coordinate points, archaeologists employ the Vulcan Measurement System. This is a portable, hand-held device that allows for real-time point recording up to a range of 30 meters. Because the system works using an offset and adjustable measuring tip, it is an essential tool for mapping in situations where line of sight to the target is obscured.
Photogrammetry (in development)
The team is currently developing proficiencies in 3D documentation and coordinate measurement through the use of close range photogrammetry. The photography-based technique creates spatial measurements by triangulating known points through the comparison of two or more photographs. The technique can track known points on an object’s surface. The points recorded are identified in the photographic data and used to generate a 3D reconstruction. For large scale reconstruction the technique can create photorealistic 3D models with speed and efficiency.
Digital Modeling and Inspection
In addition to data collection and documentation, archaeologists have also developed expertise in modeling and comparative analysis or inspection of 3D data. Using industry-standard software packages, 3D point-cloud data can be aligned and merged to produce composite polygonal models in a variety of formats. These models can then be subjected to a number of procedures including inspection, deformation analysis, texture mapping, and reverse engineering. This is particularly useful for detailed surface studies, documenting changes over time of an artifact undergoing conservation treatment, or the rapid prototyping/digital printing of objects.
3D Visualization and Interpretation
3D data collected over the course of the Hunley Project has been studied primarily through the use of a 3D site plan. CAD-based software allows the integration of polygonal models into a single platform that incorporates the many layers of the archaeological information. The digital site plan is a critical tool that enables archaeologists and other researchers to virtually view, manipulate, and analyze the submarine and the entire artifact assembly. Based on this work, the team is also developing methodologies for integration non-spacial and spacial data, such as pointcloud and x-ray computed tomography, into a uniform 3D digital platform.
Examination and Documentation
Examination and Documentation is the foundation for any treatment plan. Before treatment can begin, conservators record, both in writing and with various image-recording techniques, the current condition of the material to better understand its method of fabrication, its current condition and possible cause of deterioration. Although conservators can gather considerable information during visual examination and documentation, more sophisticated investigation techniques may be required. Examples of scientific techniques available at the WLCC include digital x‐radiography, 3-D scanning, Raman spectroscopy and scanning electron microscopy.
Treatment / In Situ Treatment
Treatment includes techniques implemented by conservators to directly intervene with the object to enhance its stability, appearance and long-term preservation. Examples of treatments undertaken at the WLCC include stabilization, cleaning, repair and restoration. Stabilization may include treatments such as chloride extraction from archaeological or historical metal artifacts and freeze drying of waterlogged organic materials. Cleaning treatments may include mechanical, micro-abrasion, chemical or electrochemical techniques, depending on the object and the type of deterioration. Restoration often includes techniques, such as repair and reconstruction, to bring an object back to a known or assumed former condition, most commonly for interpretive purposes.
Preventive Conservation is the management of environmental conditions to slow down deterioration processes and reduce or eliminate the need for interventive treatment. Conservators at the WLCC implement specific procedures and policies to control environmental variables such as relative humidity, temperature, oxygen and light levels. Preventive conservation also includes recommending appropriate conditions for exhibition and loan of cultural property, managing access and handling, prescribing suitable procedures for storage and display, packing and transport, implementing an integrated pest management plan, and strengthening emergency preparedness guidelines and response.
Education and Public Outreach
Education and Public Outreach is a priority at the WLCC. Conservators are regularly involved in teaching and outreach activities including lectures, presentations and workshops for professional groups and the general public. The laboratory actively participates in supervising and mentoring internships for conservation students and professionals. Teaching capabilities of WLCC conservators range from theoretical principles and ethics of conservation to specific case studies, techniques and methodologies.