Reconstructing the Baiban boat: A modeling project in ethnoarchaeology / Thea Yen
Thea yen Center for maritime archaeology in university of southampton
Abstract Computer graphics plays a crucial role in interpreting the archaeological works, both for academic researches and public engagements.&this&paper&will&examine the possibility of 3d& modeling& for& the& reconstruction&of&maritime&archaeological&material, the object of this project is the baiban boat, a kind of tanka sampan fishing boat, which is no longer in existence. by aiming at achieving the archaeological interpretation both in a pleasing format and precise level in the digital world, the boatbuilding of baiban will be interpreted by reconstructing it via 3d0modeling approach. Keywords ethnoarchaeology, 3d modeling, boat reconstruction
0 Introduction
This paper will explore the use of geometric based modeling method as a process of modeling interpretative reconstruction of the Baiban boat, and to present it to the public through the formation of graphic. The project is aimed at showing the ability of the computer graphics imagery in archaeology. The paper will begin by discussing the reconstruction in archaeology, and reviewing the background of Baiban boat, allowing for a proper context for the model to be interpreted, followed by the analysis of the resource of the object, by evaluating the source of evidence. Subsequently the text will demonstrate the methodology and data management about the production process. After that a discussion on this project will be carried out, evaluating the referred programs and the deficiencies of this project. Finally, a conclusion will be drawn to sum up the report, and incidentally discuss the prospect of 3D reconstruction in archaeology.
1 Reconstruction in archaeology
Currently 3D interpretation is increasingly used in research and museums (e.g. VR museum in Vietnam by laser scan [ 1]; reconstruction of the Newport medieval ship by Rhinoceros 3D [ 2];0 European Ship by Maya in digital in situ preservation archive [ 3]). When the object is reconstructed in right context, the modeling work could provide a higher level of expression for spaces and movement, as well as the exact texture of it.
The aim of this project is to produce a reconstruction of a disappeared boat, addressing 2D and 3D computer aided design and graphics skills. In terms of this reconstruction of the Baiban boat, the
intention is to communicate the research outcomes at two levels; firstly at a basic level for the general public, and secondly for a more academic audience. This is aimed at building the connection between the academic field and the public, to visualise what the studied boat should be like based on the underlying plans. With the process of building the boat in software, one could therefore gain a better understanding of the construction of the boat.
2 Background
2.1 Importance Generally, water means interaction, however, it was water that separate a group of people from the majority, water made them isolated. In southern part of China, there was a special ethnic population living on boats for the whole life, considering the water as land, which are called Tanka. The researches on the historical and folkloric aspects of this culture are sufficient. However, their dwelling place, the Tanka boat (figure 1), has not been taken seriously.
Since no first-hand description of any Tanka sampan boats had been published so far, not to mention the ones which are disappeared, it was decided to seize0 an opportunity to record their sampan boats, especially test the ability of 3D reconstructing the Baiban boat in this project. 2.2 General definition of "Tanka" boat
Tanka sampan, also known as egg boat. One of its purpose is used as a harbour boat, operated by Tanka people. Generally it is a shallow craft with a spoon-shaped bottom. It is decked both at the bow and stern, family live on the boat where is a separate area from passengers [ 4]. Generally the typical layout of the boat is, the fore-deck is used for operating the nets, the middle part of the hull is for storage, and the sheltered back is for living.
In early 20th century, there were various kinds of Tanka boats for different use, the names differ according to different operating ways (i.e. different fishing methods, different nets, amount of dwellers). 1932 statistics on Tanka people living on Pearl River
showed, there were c.100 thousands Tanka people using c.30 kinds of boats [ 5]. 2.3 The context of Baiban boat
Baiban boat has an unusual construction and represents the multiformity of the Tanka sampan beyond the common sampan construction. It shows the influence of the environmental factors, whereby the design of the vessel depends on the water condition (e.g. tides), luminous environment, wind etc. The peculiarity of this boat is reflected by its construction and operation (discuss below).
Baiban implies that this object was linked with the social practice. It has a totally different design from other Tanka sampan boats, as it was specifically constructed for one person and operated in different way. The reasons behind this have faded away through time.
3 Ethnographic parallels and sources of evidence
From0 the ethnological perspective, one can understand the "traditional" watercraft with the study of culture, filling the gap when there is no physical evidence discovered. Fortunately an interview was done in April of 2017 in the local area when most of the Tanka people don't want to recall the past hard life. The interviewee, Mr. Guo, has provided useful knowledge of Tanka boats during the interview. In terms of the types of the boat, the classification and the nomenclature of their boats mostly depend on how people operate them rather than the construction (Guo, 2017), as sampan are mostly built in the same planking technique.
The evidences for reconstructing this boat are mostly reliant on the ethnographic and iconographical information. One could gain a better insight of the object and understand the relevant social life by using the sources from the ethnographic perspective. The outcome is the answers which cannot be gained from purely archaeological survey. With first hand observation and interview with Tanka people, one could learn the object and the culture behind it, through the way in which the Tanka people view this study, what the technical choices are, which is a thick description of human behaviour in context [ 6]. However, the issues that need to be aware of is that the facts might be possibly skewed by the motives and requirements of the observer, or interviewees sometimes cannot provide the precise answers.
Using0 the0 source0 of0 iconography0 as0 evidence0 in0 archaeology0 could0 provide0 the0 detailed0 accounts0 of0 the0 records,0 but0 it0 also0 can0 lead0 to0 the0 unclear0 and0 over0 interpreted0 result.0 As0 it0 is0 based0 on0 the0 artist's0 rendition,0 they0 may0 be0 unlikely0 to0 provide0 an0 irrefutable0 definitive0 answer0 to0 an0 archaeological0 reconstruction;0 however,0 these0 could0 provide0 the0 additional0 information0 for0 the0 archaeologist0 to0 consider0 with0 a0 wide0 range0 of0 possibilities.0 From0 these0 points,0 the0 model0 in0 this0 project0 is0 considered0 as0 a0 reconstruction0 which0 places0 particular0 stress0 on0 the0 cultural0 and0 folkloric0 aspects0 representing0 the0 concept0 of0 the0 boat,0 rather0 than0 one0 with0 precise0 measurements.
4 Reading the Baiban boat
After0 the0 interview,0 Mr.0 Guo0 has0 communicated0 with0 several0 Tanka0 people0 who0 still0 keep0 the0 memory0 of0 the0 Baiban 0 boat,0 collected0 the0 information0 about0 the0 measurements,0 raw0 timber0 materials0 and0 way0 of0 operation.0 Subsequently0 he0 has0 provided0 a0 sketch0 of0 the0 boat0 (figure0 2),0 with0 the0 notes0 explaining0 how0 the0 boat0 was0 operated:0 the0 captain0 lived0 at0 the0 stem,0 a0 stone0 was0 placed0 at0 the0 bow0 for0 balancing.0 The0 two0 boards0 can0 be0 knocked-down0 with0 the0 vertical0 board0 and0 the0 strings0 in0 the0 fishing0 cabin.0 The0 boards0 were0 lacquered0 in0 white,0 this0 could0 lure0 the0 fish0 as0 fish0 have0 the0 characteristic0 of0 phototaxis.0 Fish0 cannot0 get0 out0 once0 they0 jump0 into0 the0 vessel.0 The0 basic0 measurements0 (table0 1)0 and0 construction0 materials0 (table0 2)0 are0 listed0 as0 below.
5 Survey methodology
After interviewing Tanka people about the vessel, it was decided to use Adobe Photoshop CC 2017 to ink up the three plan views of the boat, allowing for a clear view of the structure. Subsequently, the structured archive of AUTOCAD 2015 will be created based upon the obtained plans. After further discussions with the interviewee, prior to his interpretation and his perceived ideas relating to proper reconstructions was obtained. After that, additional renderings were produced in 3D studio MAX with the exported Autocad-file. Data archiving complies to archaeological guidelines [ 7].
6 Understanding hull construction by modeling
Stage 1: Producing a plan in Photoshop Initially the sketch of the boat was digitised in Photoshop, to producing the three orthographic
views, which could provide the pre-defined views and additional 2D data (figure 3). Mr. Guo's drawing is a descriptive sketch rather than a precise one, so the scales of the longitudinal view and cross section needed to be corrected in Photoshop. The plan view was created in accordance with the data from longitudinal view and the cross section. Stage 2: Hull construction AUTOCAD was the software for creating the layout of the hull, the measurements of each part were imported while building the structures, as figure x shows the 2D view of it. Firstly, the fishing cabin was squeezed out with measurement of 900 cm, followed by processing the living cabin (250 cm) and the bow cabin (80 cm). Subsequently, every parts were joined together. The modeling sequence could be considered as a hypothetical imitation of the building sequence in reality. The awnings were defined as a structure which could stretch out and draw back, comprised of two pieces (Guo, 2017). The line transect was created first, followed by squeezing out the shape of the awning, then turn into polygons. When one awning was finished, it is copied to create another one, and its size is slightly reduced to fit the structure. The vertical board was attached to the hull by using a mortise and tenon joint, the other board was roughly tied up by ropes to the hull (see figure 4 illustrating the digital construction sequence, and figure 5 is an exploded model which gives a structural interpretation). The completed hypothetical construction in AUTOCAD was showed in figure 6. Stage 3: Defining the material and texture The chosen materials (figure 7) for building every part of the Baiban boat mainly rely on the description of Mr. Guo and the information from previous shipbuilders (Guo, 2017), as there is no physical remains to provide precise information. Besides, the raw materials used in other existing Tanka sampan boat around the Pearl River are taken as reference, since the choice of timbers and the design of the structure at that area was similar [ 8]. Some designs of the structure such as that the awnings are foldable, which is a noted similarity among most of the Tanka
sampan, as the hull should be uncovered during working hours and covered up during night time, are fairly typical of Tanka sampan. Stage 4: Lighting analysis When analysing the lighting, the operation environment of the boat could be understand in a right context. Concerning this fishing boat was working at night, the first consideration was choosing the light effect at night (figure 8) to show the function of two boards which are white-lacquered for alluring the
fishes. However, this cannot result in a clear presentation of the structure. Therefore it was decided to using the surrounding at dusk. Figure 90 are the final result after V-ray rendering.
7 Data management
Data archiving is complied to archaeological guidelines. Table 3 and Table 4 showed how the data were managed in detail.
8 Discussion
8.1 Level of interpreting accuracy The reconstructed one should be considered as a representative Baiban boat, rather than an original one. There will be the uncertainty in terms of the actual parameters of the model, the data given by the observer. This is not taken in to consideration, since the aim of the reconstruction is interpreting the feature of the boat 8.2 Evaluating the project and software
Recently photogrammetric modeling is widely applied in archaeology, as it could create a model in an easier way to some extent and is suitable for publicity. From this point, it needs more effort when the object should be manually constructed with the geometric modeling method. However, photogrammetric model is generated by scanning the surface, one cannot find the actual construction of the model, while Autocad-file and Max-file could be saved and exchanged with other platform, and the solid structure could be easily accessed and further edited. They also have the possibility to achieve the reconstruction of an object when there is no physical remains for reference. The formal analysis including structure, lighting, movement, surrounding (visibility) could be mostly achieved as user's pre-defined views in these softwares.
AUTOCAD was first released in December of 1982. In June of 1992, AUTOCAD release 12 was debuted, which was the last version to support both Windows and Mac operating systems for more than 16 years [ 9]. Subsequently in October of 2010, AutoCAD 2011 for Mac was released [ 10]. AUTOCAD 2015 for Mac was used in this project, which is tailored for OS X. In any case, whether it is AUTOCAD for Windows or for Mac, Autocad-files can be saved and exchanged with other platform and on almost any release, enabling user to share files. In terms of exploring this software, using the tips shared on auto desk forums for reference will be helpful. The help menus are also recommended for tips and tricks to make the most of this software.
What needs to be noticed is the basic structure produced in AUTOCAD, which need consideration for further processing such as putting texture onto the model. The surface of the frames should be suitable for the next step; otherwise it will increase difficulty for rendering the model.
When the structure was done in AUTOCAD, the further modeling process (i.e. rendering, lighting) could be done in various programs such as 3D studio MAX, Sketch Up, Autodesk Maya and Adobe Photoshop CC. The reason for choosing 3D studio MAX is that the program has a better possibility for rendering. However, in terms of 3D public viewing, the rendered result cannot be easily accessed, as the program is mostly designed for provide a 2D rendering image. One could use this possibility to build animation by creating key frames. This model need further improvement such as produce the animation to show how the boat was operated, how did it exactly look like when it was used for fishing at night, also adding the movement and sound effect could provide a better context for it.
9 Conclusion
During the modeling process, the issues are how much conjecture will affect the level of facticity, and to not over interpret each element. Predefined view and the prospective result could be the crucial reminders when processing the model, which could guide the work in right direction and get a desirable outcome at the end. Beyond all doubt there is a lot of room for it to improve, as aforementioned the vessel could be inserted to interpret the reconstruction in a more detailed and immersed scene.
Computer graphics plays a crucial role in interpreting the archaeological works, both for academic researches and public engagements. Ideally it is possible to achieve the archaeological interpretation both in a pleasing format and precise level in the digital world. This requires the critical evaluation of the project, sufficient research of the background, precise metadata in preparation and the proficiency with the software.
Reference
[1]VR3D. First 3D Virtual Museum with 3D Scans of Ancient Relics: Ancient Sculptures of Vietnam[eb/ol]. http://vr3d. vn/trienlam/virtual-3d-museum-ancient-sculptures-of-vietnam. [2]JONES T, NAYLING N, PAT TANNER P. Digitally Reconstructing the Newport Medieval Ship: 3D Designs and Dynamic Visualisations for Recreating the Original Hull Form, Loading Factors, Displacement, and Sailing Characteristics[c]. Underwater Archaeology Proceedings, 2013. [3]Digital in Situ Preservation Archive. 16th-century Portuguese NAU[EB/OL]. https://sketchfab.com/models/814494e 93e7d434cb9c9603aeaa9fc8c. [4]PARRY M. A Dictionary of the World's Watercraft: From
Aak to Zumbra[m]. London: Chatham Publishing, 2001. [5]CHEN Xujing. The Study of the Culture of Tanka [M].
Shanghai: The Commercial Press, 1946. [6]Clifford Geertz. The Interpretation Of Cultures [M]. New
York: Basic Books, 1973: 470. [7]Archaeology Data Service. Guidelines for Depositors Version 3.0[EB/OL]. http://archaeologydataservice.ac.uk/advice/ Depositingdata#section-depositingdata-howtodeposit. [8]HUANG Xinmei. An Investigation of Boatsmen Tangka at Outlet of Pearl River[m]. Guangzhou: Zhongshan University Press, 1990. [9]David E. Weisberg. The Engineering Design Revolution
[EB/OL]. http://cadhistory.net/toc.htm. [10]CLARK D. Autodesk Adopts Apple App Store for Mac Software [EB/OL]. https://blogs.wsj.com/digits/2011/08/16/ autodesk-adopts-apple-app-store-for-mac-software/?keyWORDS=AUTOCAD （ 2018-12-01 收稿， 2018-12-18 修回）作者简介： Thea yen（1991—），女，研究方向为海洋考古、海事类文化遗产， E-mail: yy4u16@soton.ac.uk。
重构白板舟：3D建模在疍民古船复原中的应用// Thea yen作者单位：英国南安普顿大学海洋考古中心摘 要：无论在学术研究领域或是公众参与层面，电脑制图工作都在诠释考古学研究成果中起了关键性作用。运用3D建模技术对一类已经消失了的疍民古船———白板舟进行复原，旨在从考古学角度以数字化的方式精确、精美地展示文物遗迹。关键词：民族考古学 3D建模 古船复原