Polynomial

texture mapping Texture mapping is a method for mapping a texture on a computer-generated graphic. Texture here can be high frequency detail, surface texture, or color. History The original technique was pioneered by Edwin Catmull in 1974. Texture mappi ...

(PTM), also known as Reflectance Transformation Imaging (RTI), is a technique of

imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image). Imaging technology is the application of materials and methods to create, preserve, or duplicate images. ...

and interactively displaying objects under varying

lighting Lighting or illumination is the deliberate use of light to achieve practical or aesthetic effects. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing dayli ...

conditions to reveal surface phenomena. The data acquisition method is Single Camera Multi Light (SCML).

Origins

The method was originally developed by Tom Malzbender of

HP Labs HP Labs is the exploratory and advanced research group for HP Inc. HP Labs' headquarters is in Palo Alto, California and the group has research and development facilities in Bristol, UK. The development of programmable desktop calculators, ink ...

in order to generate enhanced

3D computer graphics 3D computer graphics, or “3D graphics,” sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for t ...

and it has since been adopted for cultural heritage applications.

Methodology

A series of images is captured in a darkened environment with the

camera A camera is an optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), with a ...

in a fixed position and the object lit from different angles (Single Camera Multi Light). Interactive software processes and combines the set of images to enable the user inspecting the object to control a

virtual Virtual may refer to: * Virtual (horse), a thoroughbred racehorse * Virtual channel, a channel designation which differs from that of the actual radio channel (or range of frequencies) on which the signal travels * Virtual function, a programming ...

light source. The virtual light source may be manipulated to simulate light from different

angle In Euclidean geometry, an angle is the figure formed by two rays, called the '' sides'' of the angle, sharing a common endpoint, called the '' vertex'' of the angle. Angles formed by two rays lie in the plane that contains the rays. Angles ...

s and of different

intensity Intensity may refer to: In colloquial use * Strength (disambiguation) *Amplitude *Level (disambiguation) *Magnitude (disambiguation) In physical sciences Physics *Intensity (physics), power per unit area (W/m2) * Field strength of electric, ma ...

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...

s to illuminate the surface of artefacts and reveal details. Open-source tools for processing the captured images and publishing the resulting relightable images on the web are freely available.

Applications

Polynomial texture mapping may be used for detailed recording and documentation,

3D modeling In 3D computer graphics, 3D modeling is the process of developing a mathematical coordinate-based representation of any surface of an object (inanimate or living) in three dimensions via specialized software by manipulating edges, vertices, ...

edge detection Edge detection includes a variety of mathematical methods that aim at identifying edges, curves in a digital image at which the image brightness changes sharply or, more formally, has discontinuities. The same problem of finding discontinuiti ...

, and to aid the study of inscriptions, rock art and other artefacts. It has been applied to hundreds of the

Vindolanda tablets The Vindolanda tablets were, at the time of their discovery, the oldest surviving handwritten documents in Britain (they have since been antedated by the Bloomberg tablets). They are a rich source of information about life on the northern fr ...

by the

Centre for the Study of Ancient Documents Center or centre may refer to: Mathematics *Center (geometry), the middle of an object * Center (algebra), used in various contexts ** Center (group theory) ** Center (ring theory) * Graph center, the set of all vertices of minimum eccentricity ...

at the

University of Oxford The University of Oxford is a collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the world's second-oldest university in contin ...

in conjunction with the

British Museum The British Museum is a public museum dedicated to human history, art and culture located in the Bloomsbury area of London. Its permanent collection of eight million works is among the largest and most comprehensive in existence. It docume ...

. It has also been deployed, by Ben Altshuler of the

Institute for Digital Archaeology The Institute for Digital Archaeology (IDA) is a joint venture between Harvard University, Oxford University, and the Museum of the Future (Dubai) that promotes the development and use of digital imaging techniques in archaeology, epigraphy, art hi ...

, to scan the

Philae obelisk The Philae obelisk is one of a pair of twin obelisks erected at Philae in Upper Egypt in the second century BC. It was discovered by William John Bankes in 1815, who had it brought to Kingston Lacy in Dorset, England, where it still stands today ...

Kingston Lacy Kingston Lacy is a country house and estate near Wimborne Minster, Dorset, England. It was for many years the family seat of the Bankes family who lived nearby at Corfe Castle until its destruction in the English Civil War after its incumbent o ...

and the

Parian Chronicle The Parian Chronicle or Parian Marble ( la, Marmor Parium, Mar. Par.) is a Greek chronology, covering the years from 1582 BC to 299 BC, inscribed on a stele. Found on the island of Paros in two sections, and sold in Smyrna in the early 1 ...

at the Ashmolean Museum; in both cases scans revealed significant, previously illegible text. Method was also used for identifying microscopic worked antler from

Star Carr Star Carr is a Mesolithic archaeological site in North Yorkshire, England. It is around five miles () south of Scarborough. It is generally regarded as the most important and informative Mesolithic site in Great Britain. It is as important to ...

and recording ancient rock art in

Armenia Armenia (), , group=pron officially the Republic of Armenia,, is a landlocked country in the Armenian Highlands of Western Asia.The UNbr>classification of world regions places Armenia in Western Asia; the CIA World Factbook , , and ...

. A 'dome' supporting twenty-four lights has been used to image paintings in the

National Gallery The National Gallery is an art museum in Trafalgar Square in the City of Westminster, in Central London, England. Founded in 1824, it houses a collection of over 2,300 paintings dating from the mid-13th century to 1900. The current Director o ...

and produce polynomial texture maps, providing information on condition phenomena for

conservation Conservation is the preservation or efficient use of resources, or the conservation of various quantities under physical laws. Conservation may also refer to: Environment and natural resources * Nature conservation, the protection and managem ...

purposes. Studies of the technique at the

and

Tate Tate is an institution that houses, in a network of four art galleries, the United Kingdom's national collection of British art, and international modern and contemporary art. It is not a government institution, but its main sponsor is the U ...

concluded that it is an effective tool for documenting changes in the condition of paintings, more easily repeatable than

raking light Raking light, the illumination of objects from a light source at an oblique angle or almost parallel to the surface, provides information on the surface topography and relief of the artefact thus lit. It is widely used in the examination of w ...

photography, and therefore could be used to assess paintings during structural treatment and before and after loan. Twelve dome-based systems built by the University of Southampton have been used to capture thousands of cuneiform tablets at various museums. The technique is now also finding uses in the field of forensic science, for example in imaging footprints, tyre marks, and indented writing.

References

{{Reflist

External links

Polynomial texture mapping
(

Hewlett Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...

)
Project applying polynomial texture mapping to an ancient sculpture
(

University of Southampton , mottoeng = The Heights Yield to Endeavour , type = Public research university , established = 1862 – Hartley Institution1902 – Hartley University College1913 – Southampton University Coll ...

- Archaeological Computing Research Group)
Reflectance Transformation Imaging (RTI)
(RTI overview on the Cultural Heritage Imaging website)
Sixteen interactive renderings
of Polynomial Texture Mapping (or RTI) of 8th-century illuminated manuscript, revealing difficult to see dry-point writing (

University of Oklahoma , mottoeng = "For the benefit of the Citizen and the State" , type = Public research university , established = , academic_affiliations = , endowment = $2.7billion (2021) , pr ...

)
Heritage Visualisation website
with Pixel+ viewer and an integration solution for Single Camera Multi Light datasets 3D imaging Conservation and restoration of cultural heritage Digital imaging Image processing Texture mapping Virtual reality

Origins

Methodology

Applications

See also

References

External links