Cliff Ogleby
Department of Geomatics
The University of Melbourne
Victoria, 3010, Australia
E-Mail: [email protected]
Abstract
The University of Melbourne, in conjunction with Chulalongkorn University in Bangkok, has been developing a virtual reality reconstruction of the Ancient Thai City of Ayutthaya circa 1600AD.
The visualisation is based on photogrammetry, architectural history and analogy, archaeology and site surveys. Many of the missing significant buildings have been reconstructed, and a 3d VR model of the palace precinct has been produced. The visualisation also uses live actors and video production to bring the model to life. The virtual reality model has also been compiled into a bi-lingual CD-ROM for distribution to secondary schools in the Bangkok district.
This paper will detail the photogrammetric modelling process, and illustrate how the addition of live actors can give life to an otherwise sterile virtual reality model.
Introduction
Ayutthaya is presently a modern city of around 60,000 population, some 80km from Bangkok in Thailand. Part of it is a UNESCO World Heritage Site, as it was the capital of the Kingdom of Siam for around 400 years up until 1767CE, and contains ruins of many of the religious structures from this and previous periods. In its day Ayutthaya (there are many variations in the spelling of this word like Ayuthaya, Ayodhaya and Iudea for example) was reported to be one of the most spectacular cities anywhere in the known world. Today it is a collection of monuments and precincts surrounded by the bustle of a modern regional city in Thailand.
The University of Melbourne in Australia, and Chulalongkorn University in Thailand are conducting a joint research project to re-create the greatness of Ayutthaya in the form of a photo-realistic, three-dimensional virtual world heritage model. In order to achieve this, photogrammetric records of the remaining monuments have been combined with early written records of the city and the assistance and expertise of the Royal Thai Government Fine Arts Department. The basis for the creation of the CAD models is, in many cases however, the photogrammetric record which will be described later. The models resulting from the research has formed the basis of a series of ‘visualisations’ and animations of the city, which are under continual development and enhancement.
A Glossary of Thai architectural terms is available at the end of the paper.
The Ancient city of Ayuthaya
Ayutthaya was a well established town before it became the capital of Siam, following the fall of the previous ‘capital’ at Sukhothai. It was supposedly founded by a Prince of Ut’ong (U-Thong) in the year 1350 or 1351. Or, more to the point: … So he had his troops cross over and establish themselves on Dong Sano Island…. In 712, a Year of the Tiger, second of the decade, on Friday, the sixth day of the waxing moon of the fifth month, at three nalika and nine bat after the break of dawn, the Capital City of Ayutthaya was first established [i.e., Friday March 4th 1351, shortly after nine o’clock in the morning] (Wyatt 1984, translation from Cushman). It is named after Ayodhaya, the home of Rama in the Ramayana epic, which means ‘unassailable’ in Sanskrit. It is set on an island situated at the confluence of three rivers; the Chao Phrya (also known as the Menam, which flows south to the sea via Bangkok), the Lopburi and the Pasak.
Ayutthaya became one of the wealthiest and greatest cities in Asia, and attracted the interest and awe of visitors. In the 16th Century, travellers from elsewhere in Asia and Europe were arriving in Thailand, for trade in both goods and Christianity. Visitors, traders and missionaries from Portugal arrived around 1511, from Japan around 1690, from Holland around 1605, England around 1612, Denmark around 1621 and France in 1662. Many of these foreign missions were allowed to settle effectively as ’embassies’ and it is from many of these travellers that the historical details of Ayutthaya can be discovered (for example Tachard, 1688, in Smithies 1995).
The city is associated with a high time in Thai history, with the borders of Siam extending into Burma, Cambodia and Malaysia. It was also a period of many wars, and Ayutthaya was severely damaged on several occasions. In time, the large canons of the Burmese Army once again helped to conquer the Kingdom of Ayutthaya, and on January the 7th 1767 CE the resultant fire consumed much of the inner city, destroying some 10,000 houses. Ayutthaya did not rise again, and eventually the capital of Siam moved to Bangkok leaving a ruined and plundered landscape. As a result, all that really remains of the greatness of historical Ayutthaya are the chedi, prang and defaced statues of the temples; all of the timber buildings, the palaces and the houses from the period are gone. The city of Ayutthaya was synonymous with Siam the Kingdom in the 18th Century. After the 2nd World War, on May 11 1949, Siam was renamed Prathet Thai, or Thailand as it is known to the world today.
Data Acquisition
A variety of data sources have been used in the virtual reality reconstruction of Ayutthaya. Many of the significant chedi, prangs and statues were documented using photogrammetry, giving a good geometric basis for the modelling process. Numbered targets were temporarily fixed to the monuments and coordinated using radiation surveying. Features on the monuments were also used as control points, coordinates for these points were derived from reflector-less EDM measurements. The approach taken was the more traditional stereo-photogrammetric technique, with stereo-pairs being acquired from baselines, but also augmented with convergent photography for control densification. The stereo-pairs were then measured using an Intergraph ImageStation photogrammetric system.
In addition GPS measurements were made to a series of ground control pints in anticipation of small format aerial photography (Fraser, C. S. et al, 1995) being acquired, however the discovery of recent digital base maps meant that this was not eventually necessary. This provided the three dimensional location of the structures, as well as terrain information.
This provided information on dimensions, there was the need to obtain information on many other aspects of Ancient Ayutthaya.
Missing Architectural Elements
Many of the Europeans who visited or were resident at Ayutthaya published their descriptions and impressions of the city. As most of the Thai records were destroyed when the city was razed, these publications provide some of the only information about the physical form of the monuments of Ayutthaya. Although interpreted through Eurocentric eyes, the narrative passages describe the use of gold, the materials used to construct the monuments, and the size and appearance of the buildings.
For example: About an hundred paces South of the Palace there is a great Park walled in, in the middle whereof stands a vast and high Fabric built cross-ways in the manner of our Churches, having over it five solid gilt domes of Stone or Brick, and of extraordinary Architecture, the dome in the middle is far bigger than the rest, which are on the extremities and at the ends of the Cross. This Building rests upon several Bases or Pedistals, which are raised one over another, tapering and growing narrower towards the top. The way up to it on the four sides is only by narrow and steep Stairs of betwixt thirty and forty steps three hands broad apiece and all covered with gilt Calin or Tin like the Roof… These Piramides end at the top in a long very slender Cone, extremely well gilt, and supporting a Needle or Arrow of Iron, that pierces through several Christal balls of an unequal bigness. The body of those great Piramides as well as of the rest, is of a kind of Architecture that comes pretty near ours; but it has too much Sculpture upon it, and wanting both the simplicity and proportions of ours, it comes short of its beauty, at least in the eyes of those that are not accustomed to it… All the Fabrick and Piramides are inclosed in a kind of square Cloyster, above six-score common paces in length, about an hundred in breadth, and fifteen foot high. All the Galleries of the Cloyster are open towards the Pagod; the Cieling thereof is not ugly; for it is all painted and gilt after the Moresko way… ((Tachard 1688), op. cit.)
In addition, contemporary Ayutthaya period monuments and physical model reconstructions were used as a source of information.
Modelling
The creation of the 3d CAD models of Ayutthaya commenced several years ago, and used the photogrammetric records as the basis for many of the existing chedi and buildings. The Intergraph system is capable of producing 3d CAD data from the photogrammetric record, and for the main chedi mat Wat Sri Sampet this approach was undertaken. Many of the smaller chedi were modelled from conventional photography, as the form and size were well known.
The missing features like the Palace were built using the published descriptions as the basis, with dimensional control being provided from the field surveys and base maps. Decorative elements were created from existing contemporaneous examples.
Material Maps:
In order for a high level of realism and verisimilitude to be achieved, a library of material maps were created from scanned photographs of actual surfaces. Much of the decoration found on Thai architecture is detailed and intricate, so original textures were needed.
Figure 1: Postcards from Ayutthaya
Populating the City
Many virtual reality visualisations of heritage precincts present the site as a depopulated theatre set; indeed the addition of human figures, especially moving ones, presents many difficulties. Computer generated figures very often look computer generated, the level of realism needed to remain in context with the rendered scenes is difficult to obtain. However video production techniques used in television and computer games offer the opportunity to add ‘live’ actors into sequences of computer graphics. The opportunity arose to adopt this approach in this project.
The use of ‘chroma-keying’ is now commonplace in the video special effects industry, being used in such mundane applications as evening news broadcasts and high level applications like movie and computer games special effects. The process works on replacing one particular chroma or colour in one image or image sequence with another image. The colours used are commonly the blue or green channels as these two colours are very different to human skin tones. The foreground object or actors are filmed against the single colour background, and them ‘matted’ into another video sequence comprising either live footage or computer graphics. The most well known use is in television weather broadcasts where the presenter appears in front of the weather chart, in reality the presenter is in front of a blue wall and the weather details are mixed into the scene before broadcast.
This process has been used to add traditional dancers and musicians into the audience chamber of the Grand Palace at Ayutthaya. Two dancers, six musicians, a conductor, 3 make-up artists, 4 riggers, a catering crew, a producer and translator, and a person with the cans of blue paint were engaged for a filming session in a large photographic studio in Bangkok. Digital video was acquired of the dancers performing a dance from the Ayutthaya period against the blue screen, and CD quality audio of the accompanying music was recorded. This video was later transferred into a computer, and composited with rendered computer graphic sequences from the Ayutthaya model.
Figure 2: The chroma key studio
Figure 3: The dancers and orchestra at Ayutthaya Â
Outcomes
As the project has been on-going for several years the outcomes have been many and varied. As part of the celebrations of His Majesty The King’s 50th Anniversary of Coronation the Australian Embassy in Bangkok participated in an exhibition at Ayutthaya which showcased this project. A dual language CD-ROM was prepared for the exhibition, which is in the process of being revised for potential distribution to schools in Bangkok. The CD-ROM incorporates rendered images of the reconstruction, QTVR panorama of the actual site, movies of the dancers in the audience chamber of King Narai, and supporting information.
Conclusion
This project has seen the very successful combination of Geomatics technologies to acquire primary data, and the application of historical research along with computer graphics, to produce the visualisation of a World Heritage Site. The virtual reality model of Ayutthaya was greatly facilitated by the use of photogrammetry to measure the existing monumentation, however the final product needed considerably more non-dimensional information to be a believable and historically truthful representation of this magnificant city.
Acknowlegements
This project would not have been possible without the assistance of the Royal Thai Government Fine Arts Department in Bangkok and Ayutthaya, The Thai Culture Commission, the Population and Community Development Association, The Australian Government Targeted Institutional Links Program and the Survey Engineering Department, Chulalongkorn University.
Glossary
- Bot: The building within a Wat containing the principle Buddha image
- Chedi: A venerated Buddhist structure, originally containing a holy relic but now perhaps containing a relic of a King or holy person
- Prang: Originally modelled on the corner tower of a Khmer temple. More geometric in form than a Chedi, generally has 3 niches on 3 faces and a stairway leading to a door on the fourth.
- Stupa: See Chedi
- Vihara/Wiharn: The building within a Wat which houses other Buddha images
- Wat: Generally refers to a collection of religious buildings surrounded by a wall with gateways. A wat may contain chedi, prang, vihara, bots as well as monks quarters and pavilions for relaxing and learning
References
- De La Loubere, S. (1713). Description du Royaume de Siam. MDCCXIII. Amsterdam, Gerard Onder De Linden.
- Fraser, C. S., Ogleby, C.L. and Collier, P.A. (1995). “Evaluation of a Small Format Mapping System.” The Australian Surveyor 40(1): 10-15.
- Smithies, M. (1995). Descriptions of Old Siam. Oxford University Press, Kuala Lumpur. 302p.
- Wyatt, D.K. (1984) Thailand: A Short History. Yale University Press, New Haven. 351p.
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