Papers by Kotaro Yamafune
Photogrammetric texture mapping: A method for increasing the Fidelity of 3D models of cultural heritage materials
Journal of Archaeological Science: Reports, 2018
Accurately recording information is the single most important stage of an archaeological project.... more Accurately recording information is the single most important stage of an archaeological project. The biggest technological improvement to documentation techniques in the last 15 years has been the spread of various 3D digitization technologies, such as computer vision photogrammetry and 3D laser scanning. These technologies have allowed archaeologists to quickly and accurately capture and reconstruct the geometry and colors of the subjects being studied. Each of the various methods for 3D digitization of cultural heritage materials has advantages and disadvantages, such as processing speed, cost of equipment, and the accuracy of the captured data. Laser scanned data is among the most accurate geometrical data available in modern scanning techniques, but it lacks in its ability to accurately capture textures and diagnostic coloration information. Photogrammetric data produces highly detailed photographic textures on models, but the geometric data tends to be of a lower definition th...
https://link.springer.com/article/10.1007%2Fs11457-017-9185-8, 2017
Almost three decades ago J. Richard Steffy (in: Tzalas (ed) Tropis II, pro- ceedings of the 2nd i... more Almost three decades ago J. Richard Steffy (in: Tzalas (ed) Tropis II, pro- ceedings of the 2nd international symposium on ship construction in antiquity. Athens, pp 315–320, 1990, in: Tzalas (ed) Tropis III, proceedings of the 3rd international sym- posium on ship construction in antiquity. Athens, pp 417–428, 1995) voiced the need to standardize the recording and publication of shipwrecks. Cluster analysis of construction features is difficult if archaeologists record different and non-overlapping features. This paper discusses the necessity to standardize the recording and publishing of a set of consistent and compatible basic construction features when archaeologists assess, survey, or excavate wooden shipwrecks and proposes a methodology for the recording of wooden hulls. It also emphasizes the urgency of a wide and complete sharing of archaeological information in maritime archaeology.
Journal of Cultural Heritage, 2018
Over the last few years there have been advances in technical diving, which have made it more acc... more Over the last few years there have been advances in technical diving, which have made it more accessible (including financially), making it possible to dive to greater depths and, consequently, reach underwater archaeological sites in deeper waters, which were previously considered “untouchable”. As these sites are now at potential risk of anthropic interference, new approaches to monitoring techniques are therefore considered necessary to ensure the protection of Underwater Cultural Heritage. This paper presents a protocol for monitoring techniques to be applied to ‘mid-depth archaeological remains’. The proposed technique is based on a combination of low-cost photogrammetric methods. Using as a case study a Roman era shipwreck from Majorca, off the east coast of Spain, this paper presents an ideal protocol for the essential first stages in protecting and managing the archaeological record of an underwater site at medium depth. The process gives immediate results, using photogrammetric and orthophoto coverage of the site to build up a highly accurate site map, as well as recording high-definition images in order to create a computer model of the site.
Proceedings of the 3rd Asia-Pacific Regional Conference on Underwater Cultural Heritage, 2017
In the past seven years, photogrammetry has become one of the main recording methods in maritime ... more In the past seven years, photogrammetry has become one of the main recording methods in maritime and underwater archaeology. The application of photogrammetry allows archaeologists to recreate underwater cultural heritage sites in 3D digital formats, and extract from these 3D digital models data and information required for subsequent scholarly research. The author has been using photogrammetry since 2014 and has successfully created nearly 40 underwater cultural heritage models on more than 10 archaeological projects. The projects have ranged in size, accessibility, and water clarity, introducing a number of variables to the photogrammetry of the artifacts. The variety of experiences gained on these projects have enabled the author to construct his own methodology and workflow for photogrammetric recording. In this paper, the author shares examples of his methodology and workflow for photogrammetric recording of various projects in different countries.
Este artigo aborda as experiências dos autores com a integração de ferramentas digitais à pesquis... more Este artigo aborda as experiências dos autores com a integração de ferramentas digitais à pesquisa e interpretação de sítios arqueológicos de naufrágios históricos. Para isso apresentamos um fluxo de trabalho que tem como base o uso da fotogrametria para a criação de modelos digitais tridimensionais em escala real de sítios e artefatos, que se articula nas diversas etapas metodológicas com vistas a interpretação dos sítios e a reconstrução arqueológica dos navios estudados. Os resultados são discutidos em termos do impacto da virtualização do dado arqueológico na prática acadêmica, particularmente nos aspectos de coleta, armazenamento, análise, interpretação e disseminação do conhecimento.
Methods to record shipwreck sites have evolved considerably in the past two decades. Digital tech... more Methods to record shipwreck sites have evolved considerably in the past two decades. Digital technology and marine robotics regularly present faster and more precise ways to excavate, clean, tag, and record ship remains, while computers simplify many of the steps involved in the reconstruction of ships from their archaeological remains. At the same time, the internet is creating opportunities to share primary data in real time and on a wide scale. This paper presents a methodology used by the authors to record and reconstruct the wooden structures of a 19th-century shipwreck in southern Brazil (Lagoa do Peixe site) and of a 16th-century shipwreck in Croatia (the Gnalić shipwreck).
The timber remains of a shipwreck, probably dating to the late-15th or early-16th century and fou... more The timber remains of a shipwreck, probably dating to the late-15th or early-16th century and found in 1995 at Cais do Sodré, Lisbon, Portugal, during the construction of a subway station, are described and analysed.
Proceedings of the 2014 Asia-Pacific Regional Conference on Underwater Cultural Heritage
Namban screens, a well-known Japanese art form, were painted by skillful Japanese artists from th... more Namban screens, a well-known Japanese art form, were painted by skillful Japanese artists from the late 16th century to the 17th centuries. Approximately 90 of these screens have been handed down up to the present. Not only they show some important historical scenes of European commercial activities in the Far East for the first time, but they also depict representational pictures of Portuguese ships during the Age of Discovery. Although the ships’ images on the screens are roughly acceptable, the details are often strangely anachronistic. The same images could be found in some Western maps in the 16th century. Judging from the similarity, perhaps, Japanese painters, who had never seen actual ships themselves in ports, did manage to copy the images from ones on those maps, which were brought to Japan by the wellknownTensho embassy. This was the first Japanese embassy that was sent to Europe; the diplomats left Japan in 1582 and arrived at Portugal in 1584. They met with Pope Gregory XIII and his successor, Pope Sixtus V, in Rome, and then returned back to their homeland in 1590. In the following year the embassy members succeeded in seeing HideyoshiToyotomi, who was the leading political ruler in Japan at that time. They gave him some souvenirs from Europe, including the maps. It seems that some official court painters had a chance to see those gifts, from where Japanese artists could have obtained an idea of the ships’ images that appear in the Namban screens.
Conference Presentations by Kotaro Yamafune
3rd Asia-Pacific Regional Conference on Underwater Cultural Heritage
Agisoft PhotoScan and other off-the-shelf photogrammetry software became available for archaeolog... more Agisoft PhotoScan and other off-the-shelf photogrammetry software became available for archaeologists in 2010; In 2017, after only 7 years, photogrammetry has become a one of the most frequently used recording methods for UCH (underwater cultural heritage) sites. The author of this paper works as a professional maritime archaeologist and applied photogrammetric recording on more than 35 archaeological sites in more than 10 different countries. Because of its submerged circumstances of many shipwrecks, each site has different conditions: such as visibility and colors of waters, depth, topography, water current and so on. Those different conditions create problems that requires different ways to solve those difficulties. Additionally, each project has different mission statement, or project’s goal. For that reason, each submerged site requires different types of methodologies for data-collection and data processing. Moreover, to use produced 3D digital models as archaeological data, it is important to create 1:1 scale-constrained georeferenced 3D models (Yamafune et al., 2016). Yet, to produce these accurate models, it is essential to takes a week to produce local coordinate system that gives scale and georeferenced on the model. To solve these lengthy problem, the author created a methodology that produces local coordinate system in short time (1 or 2 dives) yet provide fairly accurate results. In this paper, the author shall share his methodology of photogrammetric recording that he has developed and currently using.
The biggest technological improvement to archaeological documentation techniques in recent years ... more The biggest technological improvement to archaeological documentation techniques in recent years has been the implementation of various 3D digitization technologies, such as Computer Vision Photogrammetry and 3D laser scanning. Laser scanning produces the most accurate geometrical data available today, but it lacks the ability to accurately capture textures and diagnostic coloration information. Photogrammetric data produces highly accurate photographic textures, but the geometric data tends to be less accurate than the laser scanned data.
In this paper, the authors present a new methodology that combine advantages of laser scanner and Computer Vision Photogrammetry; applying photorealistic photogrammetry textures on geometry of laser scanned 3-D digital models. This methodology allows archaeologists to have a 3-D digital model that possesses laser scan quality geometry with photorealistic textures. Furthermore, archaeologist can apply this methodology to various laser scan dataset which is from artifacts captured by FaroArm to landscapes captured by a multi-beam sonar.
To use 3-D photogrammetric models as scientific data, it is essential for archaeologists to use l... more To use 3-D photogrammetric models as scientific data, it is essential for archaeologists to use local coordinate systems to constrain their photogrammetric models to 1:1 scale. This enables archaeologists to take measurements directly from their models. Direct Survey Methods (DSM) are often used to create local coordinate systems; however, DSM often requires several days of diving operations, which may become problematic when recording large or deep-water sites.
As a quick alternative method, the authors propose “Tri-Closure.” This method uses only three control points, placed to form an isosceles triangle. The coordinates of the control points can be calculated using the Pythagorean Theorem. After the initial photogrammetric recording, coordinates of any points within the enclosed area are automatically established. Tri-Closure is advantageous for photogrammetric recording because it requires only one or two diving operations to set up. In this paper, the authors will explain the step-by-step process of the proposed method.
Since the ancient time, people built watercrafts to across ocean. At the end of the 15th century,... more Since the ancient time, people built watercrafts to across ocean. At the end of the 15th century, development of technology allowed European to across Atlantic and Indian Oceans. This technological advancement triggered the Age of European Expansion. The main actors of this phenomena was Spanish and Portuguese, or Iberians. Today, thanks to both historical and archaeological evidences, archaeologists can reconstruct appearances of Iberian ships of this era using computer aided 3-D drawing and modeling software. In this paper, the author explains his reconstruction of the Iberian ships based on both archaeological and historical evidences.
In June 2015, Texas A&M University, the Institute of Nautical Archaeology and the Lake Champlain ... more In June 2015, Texas A&M University, the Institute of Nautical Archaeology and the Lake Champlain Maritime Museum hosted a field school at Shelburne Bay, Lake Champlain. Along with manual recording by archaeologists, the team applied photogrammetric recording to Wreck 2 (Agisoft PhotoScan). The goal of this recording was to create an accurate 1/1 scale constrained model to use as archaeological data. However, low visibility of the water (2-5 ft.) and the sheer size of the wreck (135 ft. 6 in. in length) created difficult conditions to apply photogrammetry. This talk will share various hints on how we successfully created an accurate 1:1-scale constrained photogrammetric model of Wreck 2 at the Shelburne site, despite these adverse conditions.
Archaeological work and cultural heritage management are significantly limited by time, personnel... more Archaeological work and cultural heritage management are significantly limited by time, personnel, and financial resources. Many submerged and terrestrial archaeological sites are fragile, and are located in easily accessible areas, leaving them exposed to destructive processes. The successful management of our cultural heritage involves regularly monitoring each site, but most management groups lack sufficient resources to conduct detailed surveys that include metrics, qualitative assessments, and comprehensive visual documentation. The use of three-dimensional, photographic modeling techniques can overcome many of these logistical issues by contributing substantial and informative data that can visually document a site accurately, and provide the means to measure, describe, and assess the condition and risks present.
In recent years, applications of Computer-Vision (multi-image) photogrammetry became popular in m... more In recent years, applications of Computer-Vision (multi-image) photogrammetry became popular in maritime archaeology. This technology has been repeatedly tested in archaeological surveys and excavations in dry and submerged environments. Yet, there are still active discussions about the efficiency and accuracy of Computer-Vision (multi-image) photogrammetry models.
A team from the Nautical Archaeology Program at Texas A&M University developed a methodology to record and analyze underwater shipwreck sites with off-the-shelf software, including Computer-Vision (multi-image) photogrammetry. This methodology produced reliable archaeological data, based on 1:1 scale-constrained photogrammetry models, such as 2D site plans, hull lines, and timber catalogues.
This paper details a user-friendly methodology for underwater archaeological recording and explains step by step the tasks required to produce accurate 3D models, geo-referenced high-resolution photo mosaics, section profiles, and high-quality visual tour animations.
Namban screens, a well-known Japanese art form, were painted by skillful Japanese artists from th... more Namban screens, a well-known Japanese art form, were painted by skillful Japanese artists from the late 16th century to the 17th centuries. Approximately 90 of these screens have been handed down up to the present. Not only they show some important historical scenes of European commercial activities in the Far East for the first time, but they also depict representational pictures of Portuguese ships during the Age of Discovery. Although the ships’ images on the screens are roughly acceptable, the details are often strangely anachronistic. The same images could be found in some Western maps in the 16th century. Judging from the similarity, perhaps, Japanese painters, who had never seen actual ships themselves in ports, did manage to copy the images from ones on those maps, which were brought to Japan by the well known Tensho embassy. This was the first Japanese embassy that was sent to Europe; the diplomats left Japan in 1582 and arrived at Portugal in 1584. They met with Pope Gregory XIII and his successor, Pope Sixtus V, in Rome, and then returned back to their homeland in 1590. In the following year the embassy members succeeded in seeing Hideyoshi Toyotomi, who was the leading political ruler in Japan at that time. They gave him some souvenirs from Europe, including the maps. It seems that some official court painters had a chance to see those gifts, from where Japanese artists could have obtained an idea of the ships’ images that appear in the Namban Screens.
On December 2012, a joint team composed of students from the Netherlands (Dutch Cultural Heritage... more On December 2012, a joint team composed of students from the Netherlands (Dutch Cultural Heritage Agency), the United States (Texas A&M University), and Brazil (the Museum of Archaeology and Ethnology at University of Bahia) carried out an expedition on a 17th century Dutch and Portuguese shipwreck site off the coast of Salvador, Bahia, Brazil. The short 2012 field season entailed the recording of current conditions of the site and the creation of a 3D siteplan based on archaeological data. Workflow integrated traditional trilateration techniques, G.I.S. and cutting-edge virtual modeling using shelf computer software, such as Site Recorder, ArcGIS, and Autodesk Maya. This paper will discuss preliminary results and the potential for future research in the site.
Thesis Chapters by Kotaro Yamafune
In 2010, a new off-the-shelf software for Computer Vision Photogrammetry, Agisoft PhotoScan, beca... more In 2010, a new off-the-shelf software for Computer Vision Photogrammetry, Agisoft PhotoScan, became available to nautical archeologists, and this technology has since become a popular method for recording underwater shipwreck sites. Today (2015), there are still active discussions regarding the accuracy and usage of Computer Vision Photogrammetry in the discipline of nautical archaeology. The author believes that creating a 1:1 scale constrained photogrammetric model of a submerged shipwreck site is not difficult as long as archaeologists first establish a local coordinate system of the site. After creation of a 1:1 scale constrained photogrammetric model, any measurements of the site can be obtained from the created 3D model and its digital data. This means that archaeologists never need to revisit the archaeological site to take additional measurements. Thus, Computer Vision Photogrammetry can substantially reduce archaeologists’ working time in water, and maximize quantity and quality of the data acquired.
Furthermore, the author believes that the acquired photogrammetric data can be utilized in traditional ship reconstruction and other general studies of shipwrecks. With this idea, the author composed a new methodology that fuses Computer Vision Photogrammetry and other digital tools into traditional research methods of nautical archaeology. Using this method, archaeologists can create 3D models that accurately represent submerged cultural heritage sites, and these can be used as representative archaeological data. These types of representative data include (but are not limited to) site plans, technical artifact or timber drawings, shipwreck section profiles, georeferenced archaeological information databases, site-monitoring systems, digital hull fragment models and many other types of usable and practical 3D models. In this dissertation, the author explains his methodology and related new ideas.
Namban screens are a well-known Japanese art form that was produced between the end of the 16th c... more Namban screens are a well-known Japanese art form that was produced between the end of the 16th century and throughout the 17th century. More than 90 of these screens survive today. They possess substantial historical value because they display scenes of the first European activities in Japan. Among the subjects depicted on Namban screens, some of the most intriguing are ships: the European ships of the Age of Discovery.
Namban screens were created by skillful Japanese traditional painters who had the utmost respect for detail, and yet the European ships they depicted are often anachronistic and strangely. On maps of the Age of Discovery, the author discovered representations of ships that are remarkably similar to the ships represented on the Namban screens. Considering the hypothesis that ships of some of the Namban screens are copies of ships represented on contemporary European cartography, the author realized that one particular historical event connecting Europe and Japan may be the source of these representations. This was the first visit of the Japanese Christian embassy, the Tensho Embassy, to Rome, in 1582. Its journey to Europe and its following visit to the Taiko, or first effective leader of Japan, Hideyoshi Toyotomi, may have been a trigger for the production of one of the most well-known Japanese artworks, the Namban screens.
Animations for Nautical Archaeology by Kotaro Yamafune
In June 2015, Texas A&M University hosted a field project at Shelburne Bay, Lake Champlain. This ... more In June 2015, Texas A&M University hosted a field project at Shelburne Bay, Lake Champlain. This field season focused on Wreck 2, a steamboat most likely from the 1830s. After its retirement, the steamer was sunk intentionally to provide a wooding dock for the working steamboats (as evidenced by mountains of stones). The site at Shelburne Bay, occupying an area only 100m by 150m, contains three steamers all built in the 1830s. These excellent archaeological examples provide us with a concentrated look into the early development of steamboat construction in North America’s inland waterways.
Along with manual recording by archaeologists, the team applied photogrammetric recording to Wreck 2 (Agisoft PhotoScan) under 50cm to 1.5m visibilities of water. The goal of this recording was to create an accurate 1:1 scale-constrained model to use as archaeological data. To create a 1:1 scale-constrained model, the team applied Direct Survey Methods (3H Site Recorder) and collected 107 measurements to establish a local coordinate system.
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Papers by Kotaro Yamafune
Conference Presentations by Kotaro Yamafune
In this paper, the authors present a new methodology that combine advantages of laser scanner and Computer Vision Photogrammetry; applying photorealistic photogrammetry textures on geometry of laser scanned 3-D digital models. This methodology allows archaeologists to have a 3-D digital model that possesses laser scan quality geometry with photorealistic textures. Furthermore, archaeologist can apply this methodology to various laser scan dataset which is from artifacts captured by FaroArm to landscapes captured by a multi-beam sonar.
As a quick alternative method, the authors propose “Tri-Closure.” This method uses only three control points, placed to form an isosceles triangle. The coordinates of the control points can be calculated using the Pythagorean Theorem. After the initial photogrammetric recording, coordinates of any points within the enclosed area are automatically established. Tri-Closure is advantageous for photogrammetric recording because it requires only one or two diving operations to set up. In this paper, the authors will explain the step-by-step process of the proposed method.
A team from the Nautical Archaeology Program at Texas A&M University developed a methodology to record and analyze underwater shipwreck sites with off-the-shelf software, including Computer-Vision (multi-image) photogrammetry. This methodology produced reliable archaeological data, based on 1:1 scale-constrained photogrammetry models, such as 2D site plans, hull lines, and timber catalogues.
This paper details a user-friendly methodology for underwater archaeological recording and explains step by step the tasks required to produce accurate 3D models, geo-referenced high-resolution photo mosaics, section profiles, and high-quality visual tour animations.
Thesis Chapters by Kotaro Yamafune
Furthermore, the author believes that the acquired photogrammetric data can be utilized in traditional ship reconstruction and other general studies of shipwrecks. With this idea, the author composed a new methodology that fuses Computer Vision Photogrammetry and other digital tools into traditional research methods of nautical archaeology. Using this method, archaeologists can create 3D models that accurately represent submerged cultural heritage sites, and these can be used as representative archaeological data. These types of representative data include (but are not limited to) site plans, technical artifact or timber drawings, shipwreck section profiles, georeferenced archaeological information databases, site-monitoring systems, digital hull fragment models and many other types of usable and practical 3D models. In this dissertation, the author explains his methodology and related new ideas.
Namban screens were created by skillful Japanese traditional painters who had the utmost respect for detail, and yet the European ships they depicted are often anachronistic and strangely. On maps of the Age of Discovery, the author discovered representations of ships that are remarkably similar to the ships represented on the Namban screens. Considering the hypothesis that ships of some of the Namban screens are copies of ships represented on contemporary European cartography, the author realized that one particular historical event connecting Europe and Japan may be the source of these representations. This was the first visit of the Japanese Christian embassy, the Tensho Embassy, to Rome, in 1582. Its journey to Europe and its following visit to the Taiko, or first effective leader of Japan, Hideyoshi Toyotomi, may have been a trigger for the production of one of the most well-known Japanese artworks, the Namban screens.
Animations for Nautical Archaeology by Kotaro Yamafune
Along with manual recording by archaeologists, the team applied photogrammetric recording to Wreck 2 (Agisoft PhotoScan) under 50cm to 1.5m visibilities of water. The goal of this recording was to create an accurate 1:1 scale-constrained model to use as archaeological data. To create a 1:1 scale-constrained model, the team applied Direct Survey Methods (3H Site Recorder) and collected 107 measurements to establish a local coordinate system.