Documenting archaeological boat finds digitally in 3D
In this article the method and process of documenting boat and ship finds at the Norwegian Maritime museum are described.
History
As the NMM is responsible for the recording of all ships over 100 years old the documentation laboratory generally has a number of projects running simultaneously. The NMM first acquired a FARO-arm in 2007 to record the boat finds from the Tunnel project in Oslo. While this project was underway the Barcode project was beginning which resulted in the discovery of thirteen, 16th to 17th century, lap-strake boats. This major discovery warranted the acquisition of an additional FARO-arm and additional staff to carry out the recording. Currently there is a team of seven people working with the FARO-arms to record boat parts. To date the laboratory has recorded the boats Sørenga 7, 8 and 9 and five of the thirteen Barcode boats (6/12, 7, 8, 9/13 and 14). In addition the laboratory has documented 13 fragmented boat remains from the Tunnel project, along with a large number of single piece finds from the same area. Parts of the large 14th century Bøle ship has also been documented by FARO-arm.
Boat models have been made in a scale of 1:5 of Barcode 6 and 1:10 of Sørenga 7. Currently a project is underway to reconstruct Barcode 6 in full scale. See the progress of the båtlab’en at the blog and at Facebook. Barcode 6 is currently being preserved in PEG with the intention of reconstructing it and displaying it in the future.
Process
The recording process begins with drawing each timber with FARO-Arm in Rhino software. First the orientation of the timber is established by referring to the plan drawings done in the field during the excavations. Planks are recorded in two sides while frames, knees, keels and stem and stern parts are recorded in four sides. Particular attention is paid to nail holes and treenail (wooden nails) holes so that the boats can be reconstructed in 3D or reconstructed as boat models. Other features recorded are tool marks, the placement of caulking (waterproofing material) and the impressions of other boat parts indicating their position (frames in particular).
Additional documentation such as timber sheets and photographs are used to ensure a thorough recording of all boats.
Documentation template
The NMM is using a documentation Rhino-template developed in Roskilde, and later enhanced at the Newport ship project (Jones 2007). It has been modified to meet specific needs at the Barcode-project, but is in principle identical. It has also been translated in to Norwegian language, so as to implement specific Norwegian terms and expressions.
Post-recording
For the sake of storing the files in a different file type than digital 3D, NMM has chosen to prepare all the files for print out in 2D. This means that all files needs to be split up and presented flat on paper. 2-sided timbers are separated, displaying both the inner and outer faces, while 4-sided timbers are separated and display four sides, forward, after, starboard and portside. The problem of printing out curved objects in 2D (flat) has been solved by flattening out the 3D files before printing them. This method has only been used for the curved planks, with awareness that there is a risk of distorting the data.
The 2D print-outs also serve the physical model building. The NMM has chosen to print out the frames, keel and stem/stern as 3D plastic models for use in the ship models. The planks for the strakes are printed out on paper and glued to cardboard in the required thickness. There are several reasons for using this technique. One major reason is that it saves time. The necessary building of solids for 3D-print outs is extremely time consuming. Another benefit of using cardboard strakes is it allows the use of the coloured layers, applied in the documentation process, through the whole model building process.
Conservation and display
The NMM is working on developing a method of securing the shape of the timbers through the conservation process, making it possible to reconstruct the boats in an exhibition. The Barcode 6 will be the first boat to undergo this process at the NMM. In short this means it will have to undertake freeze drying in shaped moulds, to make up for the inflexibility that freeze drying ads to the originally flexible timbers. The digital recording of the physical model in 1:5 will work as an important base for making these moulds. The digitalization of the cardboard model was also done using the FARO-arm.
