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Newly discovered and previously documented Late Neolithic chalk plaques from the Stonehenge locality have been subjected to new, non-invasive techniques which allow access to previously unseen elements of archaeological evidence. The application of these methods – involving Reflectance Transformation Imaging (RTI) and Polynomial Texture Mapping (PTM) – has revealed detail of the surface preparation and allowed methods and sequence of the compositions to be unpicked, clarifying their complexities. The results reveal a range of approaches to the compositions, some of which demonstrate planning, order, and intention while others include less systematic, rapidly executed sketches. Investigations of lines and surfaces have been made, supplemented by preliminary studies of replicated test pieces, to examine potential implements used in their creation and remark on plaque biographies and surface attrition following manufacture. Furthermore, detail revealed by RTI provides indications of the orientations in which some of the plaques should be viewed and – in one instance – suggests a ‘reflected’ element that may not be entirely abstract. Results from improved radiocarbon determinations place the plaques in the early part of the 3rd millennium bc which, together with identification of individual motifs, allows the plaques and the designs to be reconsidered within the corpus of Neolithic art in the British Isles.

We present reflectance transformation imaging (RTI) as a documentation tool for visualizing and recording the treatment of coins. RTI—a computational photograph technique that calculates light positions—allows interactive relighting for vision. Virtual light enhances surface details for examining morphological difference. By applying Dome RTI method, stages of conservation treatment were recorded to enhance the overall characteristic features of the relief upon the coin surface, and then detect and identify weathered characters. Patina removal and consolidation were documented along with the original state; a significant difference in the coin’s surface was observed using different filters of the RTI viewer. Specular enhancement and normal visualization results were most effective for detecting the change in morphology and reflectivity. Microscopic RTI was applied to visualized minimal changes of characters between treatment stages. Character “常” of coin 1 showed changes in the cleaning of dirt and removal of alumina powder. The character “元” of coin 3, originally covered by a thick patina, revealed clear strokes using virtual relighting through RTI. These documentation images indicate that RTI is a promising tool to support manual recording of conservation stages and, furthermore, allow detection of areas difficult to visualize through the human eye.

Corn mummies’ were funerary objects in ancient Egypt that were served as sacred images of the god Osiris during the Khoiak feast. They are grain-filled linen sacs, usually filled with an emmer or barley specimen, the ingredients for staple food in ancient Egypt (bread and beer). In the fertility cult of Osiris, the function of Corn mummies was presumably for continuous prosperity of the land and healthy crop growth. This paper focuses on the use of nondestructive methods for the documentation and visual examination of a Corn mummy coffin (No. 1242) dating back to the late period; but its original inscriptions are partially lost. Digital imaging and Reflectance Transformation imaging (RTI) were used to document all surface aspects. D-stretch was used to enhance surface details that were not clearly visible by digital imaging and RTI. Infrared imaging was used to reveal the details of hieroglyphic inscriptions and outline drawings on the wooden coffin. X-ray radiography was used to non-destructively verify the inside contents of the wrapped mummy inside the wooden coffin, and whether it includes any human remains or not. The methods provided a comprehensive documentation and examination of the various parts of the artifact.

Virtual Reflectance Transformation Imaging (V-RTI) is a hybrid method that combines 3D, Virtual Reality (VR) and 2D+ technologies into a rapid, lightweight, and user-friendly method of recording archaeological monuments in the field. The resultant image file can be interactively lit from various positions to highlight surface texture and detail not generally visible to the naked eye. In this article, we describe the V-RTI method and critically compare it to the current standard Highlight (H-RTI) method. We present results of a field trial of V-RTI in a challenging urban environment that yielded a new inscription, new readings, and epigraphic palimpsests that significantly change our understanding of the ancient Lycian city of Telmessos. We conclude that V-RTI is a valuable new tool for recording at-risk heritage worldwide and should be considered a default recording tool for field survey and conservation for many different classes of field monument.

This work presents digital imaging technology as a tool for studying artists’ brushstroke patterns and painting techniques. Digital imaging analysis performed using reflectance transformation imaging (RTI) and three-dimensional (3D) scanning was used to observe the morphological textures of brushstrokes formed on the painted surface; this provided a “digital fingerprint” to indicate an individual artist’s specific characteristics. A model specimen was produced to examine the relationship between paint and painting tools. For painting tools, twelve types of brushes were chosen from the artist’s studio. The results revealed distinctive features among the different types of brushes. The model specimen was then further compared with the artist’s works and a replicated painting was also produced for comparison with one of the original works. The overall result provided information about similar patterns corresponding to the types of brushes the artist used for the model specimen and paintings. Distinctive painting pattern features were detected in the replica, although it was painted using the same material and type of brush.

Reflectance Transformation Imaging (RTI) was used to record an inscription carved on the surfaces of 17 limestone blocks of the Yalburt Yaylası Sacred Pool Complex (Konya), which dates from the XIIIth century B.C. After a brief introduction concerning the site and the RTI technique, and particularly its Highlight-RTI variant, this paper reports on the imaging strategy tailored to the conditions of this specific landscape monument, which contains blocks of various dimensions organized along three axes. While various applications of the RTI technique on open-air examples have been reported in the literature to date , our experience on the Yalburt Yaylası Sacred Pool Complex presents a large-scale application of Highlight-RTI on a complex monument. The paper concludes that RTI is an efficient tool for documenting landscape monuments when the needs of each site are carefully analyzed. In this large-scale capacity, RTI works best as a site-specific technique customized to the particulari-ties of each locale., MÖ XIII. yüzyıla tarihlenen Yalburt Yaylası Kutsal Havuz Kompleksi’nde (Konya) 17 adet kireçtaşı bloğun yüzeylerine kazınmış yazıtın kayıt altına alınması için Yansıtma Dönüşümlü Görüntüleme (Reflectance Transformation Imaging, RTI) kullanılmıştır. Anıta ve RTI’ın Highlight-RTI moduna dair kısa bir girişin ardından makale üç farklı yönde ve farklı özelliklerde bloklar içeren Yalburt anıtının sunduğu özel koşullar için tasarlanmış görüntüleme stratejisini anlatmaktadır. Her ne kadar RTI’ın açık havada kullanıldığı başka örneklere daha önce literatürde yer verilmiş olsa da, Yalburt Yaylası Kutsal Havuz Kompleksi’ne dair deneyimimiz Highlight-RTI’ın pek çok bileşeni olan bir kaya anıtı özelinde nasıl büyük ölçekli bir uygulama olabileceğini göstermektedir. Makale, yerel gereklilikler detaylı şekilde analiz edildiği takdirde RTI’ın kırsal peyzajda konumlanmış kaya anıtlarının kayıt al-tına alınması için etkili bir yöntem ola-bileceğini önermektedir. Sonuç olarak, kaya anıtlarının bu teknikle görüntülenmesinde en iyi sonuçların alınabilmesi için RTI’ın yerel koşullara uyarlanan ve o yere özgü bir biçimde özelleştirilmiş bir teknik olarak ele alınması gerektiği ortaya konulmaktadır.

Reflectance Transformation Imaging (RTI) is a photographic technique used to generate digital surrogates of surfaces that can be viewed using virtual lighting coming from interactively set directions, enabling the close structural examination of objects under digital raking light. In this study, RTI was applied to Middle Nubian pottery from sites near the Second Nile Cataract that were excavated by the Scandinavian Joint Expedition to Sudanese Nubia in the early 1960s. The ceramic traditions under investigation are currently known as C-Group, Pan-Grave and Kerma. An overarching aim of the project is to assess the possibility of understanding the relationships between these groups through detailed analyses of their material traditions. Based on the hypothesis that technological traditions may be related to cultural heritage, RTI is applied in this study to observe morphological traces of ceramic vessel forming processes. Two technological groups were identified, one consistent with paddle-forming, and another consistent with hand-building on a mat-lined surface. These technological groups correspond very closely to cemetery distributions, which suggests that the different techniques may be specific to different potterymaking traditions. It is suggested that vessel forming-technology in the so-called C-Group tradition is distinct from that of the so-called Pan-Grave and Kerma traditions, and that the validity of the divisions between Nubian cultural groups should thus be further interrogated.

A Reflectance Transformation Imaging technique (RTI) realized by multi-rotor Unmanned Aerial Vehicles (UAVs) with a focus on deployment in difficult to access buildings is presented in this letter. RTI is a computational photographic method that captures a surface shape and color of a subject and enables its interactive re-lighting from any direction in a software viewer, revealing details that are not visible with the naked eye. The input of RTI is a set of images captured by a static camera, each one under illumination from a different known direction. We present an innovative approach applying two multi-rotor UAVs to perform this scanning procedure in locations that are hardly accessible or even inaccessible for people. The proposed system is designed for its safe deployment within real-world scenarios in historical buildings with priceless historical value.

Conservation investigation often includes substantial technical analysis, and digital tools now permit visitor engagement with this content in museum galleries. Reflectance Transformation Imaging (...

Bone tools have a long archaeological history, and have recently been shown to retain use-traces distinctive of different perishable crafting practices. When examined in a controlled way, these diagnostic use-traces can serve as proxies for the crafted forms the bone tools were used to produce (e.g., baskets, leather goods, etc.). However, a number of methodological stumbling-blocks have hindered the sharing of bone tool use-wear results in a consistent standardized format. We suggest the application of Reflectance Transformation Imaging (RTI), and provide details for how to construct an RTI system which resolves most problems related to reproducibility in use-trace analysis.

This paper aims to evaluate the visual quality of the dynamic relighting of manufactured surfaces from Reflectance Transformation Imaging acquisitions. The first part of the study aimed to define the optimum parameters of acquisition using the RTI system: Exposure time, Gain, Sampling density. The second part is the psychometric experiment using the Design of Experiments approach. The results of this study help us to determine the influence of the parameters associated with the acquisition of Reflectance Transformation Imaging data, the models associated with relighting, and the dynamic perception of the resulting videos

In the past few decades, a number of scholars studied painting classification based on image processing or computer vision technologies. Further, as the machine learning technology rapidly developed, painting classification using machine learning has been carried out. However, due to the lack of information about brushstrokes in the photograph, typical models cannot use more precise information of the painters painting style. We hypothesized that the visualized depth information of brushstroke is effective to improve the accuracy of the machine learning model for painting classification. This study proposes a new data utilization approach in machine learning with Reflectance Transformation Imaging (RTI) images, which maximizes the visualization of a three-dimensional shape of brushstrokes. Certain artist’s unique brushstrokes can be revealed in RTI images, which are difficult to obtain with regular photographs. If these new types of images are applied as data to train in with the machine learning model, classification would be conducted including not only the shape of the color but also the depth information. We used the Convolution Neural Network (CNN), a model optimized for image classification, using the VGG-16, ResNet-50, and DenseNet-121 architectures. We conducted a two-stage experiment using the works of two Korean artists. In the first experiment, we obtained a key part of the painting from RTI data and photographic data. In the second experiment on the second artists work, a larger quantity of data are acquired, and the whole part of the artwork was captured. The result showed that RTI-trained model brought higher accuracy than Non-RTI trained model. In this paper, we propose a method which uses machine learning and RTI technology to analyze and classify paintings more precisely to verify our hypothesis.

Reflectance Transformation Imaging has been largely used for the recording, documentation, and analysis of cultural heritage. A series of images of a static object, taken in raking light at constant exposure, is synthetized using the Polynomial Texture Mapping or the Hemispherical Harmonics fitter, resulting in polynomial texture maps or Reflectance Transformation Images. These visualizations capture colour and texture information, revealing low relief detail and emphasizing surface topography. RTI has found several applications in the study of painted surfaces, yet it has not been utilized for the study of historic interiors. More commonly, this would be achieved through Architectural Paint Research, a process of examining the painted finishes to the interior or exterior of an historic structure, to establish its decorative history. Typically, this is achieved through a combination of archival research; sampling of the paint and substrate layers that are analysed at high magnification in cross-section; and through careful layer-by-layer exposures of the accumulated paint stratigraphy so that the texture, sheen and colour of the paint layer can be observed. The latter of these techniques is especially important if an underlying scheme is decorative or polychromatic. This study evaluates the use of RTI for the study of historic wall paintings, with an emphasis on the revelation of overpainted designs. Considering the efficiency of RTI in recording and documentation of subtle surface variations, this research explores the use of texture comparisons between exposed, restored and covered areas of the wall painting as a diagnostic tool and for appraising condition.

International audience; Reflectance Transformation Imaging (RTI) is a technique for estimating the surface local angular reflectance and characterizing the visual properties by varying lighting directions and capturing a set of stereo-photometric images. The proposed method, namely HD-RTI, is based on the coupling of RTI and HDR imaging techniques. The HD-RTI automatically optimizes the necessary exposure times for each angle of illumination by using the response of the scene. Our method is applied to industrial surfaces with micro-scratches from which we will estimate saliency information. Results show that coupling HDR and RTI enhance the characterization and therefore the discrimination on the surfaces visual saliency maps. It leads to an increase in robustness for visual quality assessment tasks.

Reflectance Transformation Imaging (RTI) is a computational photographic method that captures an object’s surface shape & color and enables the interactive re-lighting of the subject from any direction. RTI model of an object is built from multiple images of it captured by a stationary camera but varying light directions. By changing the direction of the light, the respective micro-geometry of the object is highlighted. The RTI acquisition process is often long, and tedious when it is not automated. It requires expertise to define for each analysed object which are the number and the relevant lighting positions in the acquisition sequence. In this paper, we present our novel Next Best Light Position (NBLP) method to address this issue. The proposed method is based on the principle of a gradient descent allowing in an adaptive and iterative way, to automatically define the most appropriate lighting directions for the RTI acquisition of an object/surface.

International audience; In this paper, we propose an automated adaptive focus pipeline for creating synthetic extended depth of field images using a reflectance transformation imaging (RTI) system. The pipeline proposed detects object regions at different depth levels relative to the camera’s depth of field and collects a most focused image for each. These images are then run through a focus stacking algorithm to create an image where the focus of each pixel has been maximized for the given camera parameters, lighting conditions, and glare. As RTI is used for many cultural heritage imaging projects, automating this process provides high quality data by removing the need for many separate images focused on different regions of interest on the object. It also lowers the skill floor for this image collection process by reducing the amount of manual adjustments that need to be made for focus. Furthermore, this can help to minimize the amount of time that a sensitive cultural heritage object is outside of its ideal preservation environment.

Reflectance Transformation Imaging (RTI) is a non-invasive method of examination which can be used to document and visualize the surface texture of objects, including artworks. Through imaging an object under different directions of illumination, topographical maps of a low relief surface can be produced, which when further processed can be used as an interactive visual aid. This paper summarizes the current state of research on micro-RTI, and presents an investigation into a micro-RTI system comprised of a digital microscope and miniature lighting array dome, which was originally developed to study small areas of surface texture. The article reviews the techniques required to adequately use the micro-RTI, and evaluates the system’s use as a practical tool for conserving and documenting modern and contemporary easel paintings. This was determined by evaluating its data processing, ability to accurately document test panels and case study paintings, and comparing it with alternative documentation methods of standard microscopy and laser scanning. It was found that micro-RTI is a useful tool for modern and contemporary paintings and their often complex and/or delicate surfaces, where subtle surface alterations can result in visually distracting features.

International audience; Reflectance Transformation Imaging (RTI) is a technique for estimating surface local angular reflectance from a set of stereo-photometric images captured with variable lighting directions. The digitization of this information fully fits into the industry 4.0 approach and makes it possible to characterize the visual properties of a surface. The proposed method, namely HD-RTI, is based on the coupling of RTI and HDR imaging techniques. This coupling is carried out adaptively according to the response at each angle of illumination. The proposed method is applied to five industrial samples which have high local variations of reflectivity because of their heterogeneity of geometric texture and/or material. Results show that coupling HDR and RTI improves the relighting quality compared to RTI, and makes the proposed approach particularly relevant for glossy and heterogeneous surfaces. Moreover, HD-RTI enhances significantly the characterization of the local angular reflectance, which leads to more discriminating visual saliency maps, and more generally to an increase in robustness for visual quality assessment tasks.

Printed Circuit Board (PCB) has the situation of expansion or shrinkage in the manufacturing processing. Moreover, the circuit is more complicated and the line width/spacing is more precise, so that the circuit file becomes very large. Traditionally, four-point registration holes and sub- block are used for the bilinear compensation. Although the traditional methods can be quickly compensated, it cannot enhance the precision. In contrast, using the polynomial compensation can have good precision but time consuming. Moreover, considering the IPC (Industrial Personal Computer) heat dissipation and cost issues, GPU (Graphics Processing Unit) card is rarely used at the factory. In present, Intel CPU contains the Intel® HD graphics which is implemented the bilinear technology by OpenGL texture mapping. Therefore, this paper proposed the polynomial texture mapping algorithm by OpenGL, which calculated the nonlinear straight trace according to the registration holes. The non-uniform interpolation control points are generated by using the slope relationship of the registration holes. Finally, using Intel® HD graphics on multiple IPCs, multi-thread division processing and pipeline processing which can improve the precision of PCB compensation and save the computing time. The experimental results show the proposed method has the smallest XOR (Exclusive-OR) value at the 2.5um resolution and 1um resolution. Meanwhile, the computing time can still maintain 1.749 seconds at the 2.5um resolution and 9.588 seconds at the 1um resolution. In addition, the offset less than 1 pixel of the polynomial texture mapping algorithm accounts for about 65 percent at the 2.5um resolution, and the offset less than 2 pixels of the polynomial texture mapping algorithm accounts for about 57 percent at the 1um resolution. Finally, simulate two IPCs computing time in the image size 510mm x 610mm (resolution is 25400dpi) through the proposed method in this paper, we obtain the 20.618s on IPC1 and 20.30s on IPC2 which is better than [8]. The proposed method in this paper can not only quickly compensate PCB substrate but also solve the problem of low precision.

Reflectance Transformation Imaging (RTI) is a computational photography technology that allows interactive manipulation of virtual lighting within two-dimensional images to enhance object surface information. RTI is based on the reflection characteristics of the surface of the object characterized by a specific parabolic function, of which the most classic is Polynomial Texture Mapping (PTM) based on biquadratic polynomial. Therefore, RTI is ideal for diffusely reflecting objects, and metal materials with specular reflection are nearly out of consideration before. In this article, several metal samples with different surface topography were selected to explore the potential of RTI for subtle traces on metal surfaces. The results show that, with the cooperation of different image enhancement algorithms, especially Specular Enhancement and Diffuse Gain, RTI can be well applied to the detection of metal, even metal with relatively strong specular reflection. And the No-Reference Structural Sharpness (NRSS) assessment is consistent with subjective perception, confirming that RTI not only helps to explore the 2D or 3D geometric texture of the surface of metal materials, but also plays an important role in understanding and spreading the cultural phenomena implied in the content on metal surfaces. Promisingly, RTI is expected to be extended to a wider range of fields.

Fundacao para a Ciencia e a Tecnologia, Portugal (Grant Nos. UIDB/04349/2020 and UID/FIS/04559/2019)- Private funds. V.C. acknowledges the support from UID/Multi/04349/2019. J.C. acknowledges NOVA.ID.FCT. This article examines the development of a low-cost and portable set-up controlled by an Arduino board to perform Reflectance Transformation Imaging technique, from the information derived from 45 digital photographs of an object acquired using a stationary camera. The set-up consists of 45 high-intensity light emitting diodes (LEDs) distributed over a hemispherical dome of 70 cm in diameter and a digital camera on the top of the dome. The LEDs are controlled by an Arduino board, and the user can individually control the LEDs state (ON or OFF) and duration of illumination. An old manuscript written with iron-gall ink and a set of 1 Euro coins mint in 2002 were photographed with the set-up. The interactive re-lighting and the mathematical enhancement of the object's surface revealed corrosion, loss of material, scratches and other details, which were not perceived in standard images. These unique features, which can be extracted using edge detection processing, have immediate application in different fields such as cultural heritage or forensic studies, where they can be used as fingerprints to identify unique objects, allowing also recognizing the use of tools to alter the surface of coins to increase the price in the market. publishersversion published

The analysis of surface bone changes is an essential aspect of the paleopathological examination of skeletal remains from archaeological and forensic contexts, and proper digital imaging is an indispensable aspect of the documentation of bone modifications. This paper evaluates the applicability of Reflectance Transformation Imaging (RTI) to the study of pathological bone surface changes in human remains. Forty-five samples of human bones and teeth from medieval and early modern Estonian cemeteries were photographed and subjected to RTI imaging to document the pathological conditions that typically result in subtle surface modifications. Subperiosteal Bone Production (SBP), abnormal porosity, cribra orbitalia, endocranial lesions and lytic lesions in bone, as well as enamel hypoplasia and dental calculus in teeth were successfully represented with this technique. The results indicate that RTI allows visualization of shallow and discrete bone changes that are otherwise unnoticed. In some cases, this technique provides a better understanding of the nature and development of particular pathological processes than possible with conventional imaging. Although it cannot entirely replace microscopic and radiological techniques, RTI can be successfully performed in a reasonably short time by non-specialist operators with limited funding and resources, thus enabling identification of specimens that should be subject to more expensive or time-consuming analyses. Hence, RTI constitutes a valuable tool for the representation of subtle surface details in pathological bone, and can successfully support standard photography in paleopathological studies, museum display and scientific communication.

Photography is widely accepted as a means of forensic case documentation and evaluation. In cases of criminal dismemberment digital microscopy is commonly used to assess marks left on the bone. Reflectance transformation imaging (RTI) is a computational photography technique which documents and enhances the three-dimensional (3D) reflectance properties of the surface of an object. RTI has primarily been used in the cultural heritage sector but has recently transitioned into forensic science. This study examines the use of RTI for the documentation and presentation of cut surface characteristics on fully sectioned long bones. Juvenile pig radii were bisected using three different handsaws, chosen as handsaws are the most common implement used in criminal dismemberments. The resulting 42 cut surfaces were then documented with a digital microscope and RTI. Four rendering modes were applied to the default RTI image, with diffuse gain being the most beneficial to accentuate cut surface features. Although great care must be taken when obtaining the photographic sequences necessary for detailed RTI analysis, RTI is relatively inexpensive, expeditious, and easy to use, and creates highly detailed, virtually interactive images. RTI may not replace microscopic methods of saw mark analysis, however could prove useful for the documentation, image sharing, and presentation of forensic evidence.

Reflectance transformation imaging (RTI) is a computational photography technique widely used in the cultural heritage and material science domains to characterize relieved surfaces. It basically consists of capturing multiple images from a fixed viewpoint with varying lights. Handling the potentially huge amount of information stored in an RTI acquisition that consists typically of 50–100 RGB values per pixel, allowing data exchange, interactive visualization, and material analysis, is not easy. The solution used in practical applications consists of creating “relightable images” by approximating the pixel information with a function of the light direction, encoded with a small number of parameters. This encoding allows the estimation of images relighted from novel, arbitrary lights, with a quality that, however, is not always satisfactory. In this paper, we present NeuralRTI, a framework for pixel-based encoding and relighting of RTI data. Using a simple autoencoder architecture, we show that it is possible to obtain a highly compressed representation that better preserves the original information and provides increased quality of virtual images relighted from novel directions, especially in the case of challenging glossy materials. We also address the problem of validating the relight quality on different surfaces, proposing a specific benchmark, SynthRTI, including image collections synthetically created with physical-based rendering and featuring objects with different materials and geometric complexity. On this dataset and as well on a collection of real acquisitions performed on heterogeneous surfaces, we demonstrate the advantages of the proposed relightable image encoding.

WOS: 000450381000011, The residents of Boncuklu Hoyuk, a mixed forager-farming community dating to the pre-ceramic Neolithic c. mid-9th to mid-8th millennium cal. BC, used their hands to manipulate local clays into artefacts, often leaving behind traces of their palm prints and fingerprints on the surface of the objects. Reflectance Transformation Imaging (RTI), a digital imaging technique that uses multiple images and mathematical models to reveal the 3 dimensional shape of an artefact's surface, provides a detailed, post-processing interactive view of the prints on each artefact. Geometric clay objects are the single-most abundant artefact category at Boncuklu Hoyuk with over 1000 clay objects recovered and studied at this central Anatolian village to date. The aim of the project is to understand the manufacture, use, and disposal of geometric clay objects at Boncuklu Hoyuk through an analysis of the hand and fingerprints present on their surfaces. RTI reveals palm and fingerprints on more than half of the study sample consisting of eighty-eighty clay artefacts. Analysis of the prints using friction ridge density protocols indicates that adult females were the primary makers of the artefacts. The results were unchanged when taking into account artefact shape and type, and when considering temporal and locational data. The association of these artefacts during manufacture principally to women suggests an early link in the life of the object to women, potentially suggesting a gender based division of tasks at Boncuklu Hoyuk., Pacific Legacy Inc., This work was supported by Pacific Legacy Inc., and carried out with the kind permission of Prof. Douglas Baird and Dr. Andrew Fairbairn, directors of the Boncuklu Hoyuk Project along with Dr Gokhan Mustafaoolu, Assistant Site Director.

This article presents some of the results of the Ashmolean Latin Inscriptions Project (funded by the AHRC 2013–2017), with new editions and commentaries on inscriptions from Roman Britain in the Ashmolean Museum. It offers an evaluation of these inscriptions based upon autopsy and digital imaging (Reflectance Transformation Imaging), and includes new photographs of them. It offers insights into the culture and society of Roman Britain as well as into the changing attitudes towards Romano-British antiquities in modern Britain from the 1600s onwards.

Textiles are among the most informative items among archaeological finds. However, their physical and chemical characteristics and the effect of prolonged burial make them particularly sensitive and difficult to investigate and conserve. In keeping with conservation ethics and in order to ensure the preservation of textiles while allowing maximal retrieval of information, advanced research tools are required. Reflectance Transformation Imaging (RTI) is an imaging technique which uses reflected light to record the three-dimensional characteristics of the surface of objects. This study investigated the implementation of Micro-RTI - a novel RTI technology using a microscope - for the examination and documentation of archaeological textiles. The technique allows the capture, examination, documentation and presentation of fine surface details which often cannot be identified by ordinary photography. In this study, an assemblage of textiles of different periods from the Judean Desert, Israel, was examined. Comparison of images made by several techniques in parallel showed that Micro-RTI provides the most comprehensive information about the textiles including a significant advantage in the visual representation of the weave, the fibers, the surface and patterns of decay and erosion. The results of this study demonstrate the significant potential of Micro-RTI technology for the research and documentation of archaeological textiles.

Southern Scandinavia is Europe’s richest region in terms of figurative rock art. It is imperative to document this cultural heritage for future generations. To achieve this, researchers need to use the most objective recording methods available in order to eliminate human error and bias in the documentation. The ability to collect more data is better, not only for documentation, but also for research purposes. Recent years have seen the wider introduction of image based 2.5D and 3D modelling of rock art surfaces. These methods are Reflectance Transformation Imaging (RTI), Structure from Motion (SfM), and Optical Laser Scanning (OLS). Importantly, these approaches record depth difference and the structure of engraved lines. Therefore, they have clear advantages over older methods such as frottage (rubbings) and tracing. Based on a number of short case studies, this paper argues that 2.5D and 3D methods should be used as a standard documentation techniques, but not in an exclusionary manner. The best documentation, enabling preservation and high-quality research, should employ all methods. Approaching rock art with all the research tools available we can re-appraise older documentation as well as investigate individual action and the transformation of rock art.

This article discusses the application of Reflectance Transformation Imaging (RTI) to ancient graffiti from Herculaneum, Italy. RTI is a computational photography technique that makes it possible to digitally manipulate the light direction within a 2D image. This allows researchers to examine the graffiti (and individual details and letterforms) under a variety of lighting conditions. Furthermore, RTI is able to enhance the surface and color of the wall plaster on which the graffito was written. Several examples of this application to ancient graffiti show that RTI enables researchers to decipher graffiti, especially individual letterforms. RTI mimics the process of personal autopsy on site and allows scholars to reexamine the graffiti from anywhere in the world. In combination with other methods of archaeological documentation, RTI digitally preserves these inscriptions for the future.

The modern technology has been offering more and more tools for digitalisation of historical artefacts or works of art. Especially popular is a 3D visualisation, which allows to obtain a very realistic image of the subject. However, for many culture and science institutions, including museums, these tools are not easily available due to financial reasons. The discussed herein method of Reflectance Transformation Imaging (further RTI) seems to be a solution, which – being relatively inexpensive – offers a whole range of possibilities as far as documentation of historical artefacts is concerned. It allows – without the need of using a high-tech equipment – to create 2.5D images out of regular digital photographs. The way how the RTI method works has been shorty characterised in this article, at the same time presenting subsequent stages within the procedure of obtaining images. In order to show the results of this method, authors referred also to their own experience in RTI. They described images by themselves of three boulders with petroglyphs, which are in the possession of the Archaeological Museum in Poznań. The authors presented their own assessment of the RTI method – based on their achievements and the source literature – identifying its both positive and negative aspects.

Stone slabs with circularly arranged cup-marks (kernoi) in the Bronze Age Aegean have been interpreted as grave marks, offering tables, astronomical instruments, and recently as gameboards. This paper, in the context of the Bronze Age Akrotiri settlement, at Santorini (Thera), proposes the use of digital imaging methods for the recording of these objects. Reflectance Transformation Imaging and Structure from Motion Photogrammetry is used for the optimal recording of these objects and is proposed as a standardised method for the recording, analysis and interpretation of similar objects accross the Aegean and Eastern Mediterranean.

Human representations are one of the most important groups of depictions in rock art in southern Scandinavia. These humans have long been discussed as complete, stable, and temporally-fixed images. The results of a new survey challenge this view. Recording rock art with Reflectance Transformation Imaging (RTI) enabled us to discern a possible sequence of production of individual human representations, their bodily features, and associated objects. Figures from a rock art site in Finntorp (Tanum, Sweden) will be used as an example. Differences in the dimensions of the engraved lines, the chronology of the depicted objects, and the placement of body parts suggest that several individuals may have been involved in making human representations on the rocks, and that their appearance as complete figures is the result of repeated transformations. The results presented demonstrate that Scandinavian rock art is not stable in time. We suggest that rock art is best understood as the creation of communities over time, which enables them to engage with the past by transforming the rocks.

Discovered in the late 1970s and first published in the Bulletin of the American Schools of Oriental Research by Frank Moore Cross in 1980, the Qubur al-Walaydah Bowl has become the object of more recent inspection by the current excavation team at the site. In 2010, Angelika Berlejung proposed new readings for parts of the inscription. This article seeks to analyze Berlejung's proposed readings against Cross's readings from his editio princeps. Furthermore, the present study utilizes reflectance transformation imaging in order to draw its conclusions. Ultimately, Berlejung's proposed readings are not supported by reflectance transformation imaging.

Advanced 2-D and 3-D computer visualizations are increasingly being used for recording and documentation, analysis, dissemination, and public engagement purposes. Recent technological advances not only considerably improve data acquisition, processing, and analysis but also enable easy and efficient online presentation. This article evaluates the contributions of advanced 2-D and 3-D computer visualization and discusses the potential of 3-D modeling for recording basketry technology and documenting the state of preservation of baskets. It explores the available analysis, integration, and online dissemination tools, using as case studies recently excavated baskets from Cache Cave in southern California. Results indicate that the proposed methodology, which incorporates reflectance transformation imaging visualizations and photogrammetric 3-D models, which are further processed using 3-D modeling software and integrated analysis tools and then transformed to a Web-based format, is a useful addition to the basketry analysis toolkit.

There are multiple conservation challenges related to decorated surfaces, the majority are intimately linked to its documentation. This paper draws on wall paintings as a representative of decorated surfaces, arguing the importance of considering its fourthdimensionality – space and time – in its conservation and documentation. To that end, we propose the use of Building Information Model (BIM) as a platform to consolidate this approach together with various documentation techniques used for the conservation and management of wall paintings. This paper exemplifies this method with a case study of Myin-pya-gu Temple in Old Bagan (Myanmar); firstly, reviewing the different techniques used to document the temple and wall painting (photography, photogrammetry, laser scanning, reflectance transformation imaging (RTI); and secondly, discussing the data integration within a BIM environment. This position proposes a transition from a two-dimensional to a four-dimensional approach in wall painting conservation, potentially opening up possibilities of documentation, monitoring, simulation, or dissemination. Ultimately, the case study of Myin-pya-gu has the objective to introduce the use of HBIM as a platform for consolidating the documentation of decorated surfaces.

International audience; Reflectance Transformation Imaging is a technique that provides a digital and useful representation of an object through photometric and geometric local assessment of the surface. RTI technique consists in acquiring a sequence of images from a fixed observation position while varying the direction of the light source around the observed object. Thanks to a further reconstruction process, the continuous angular reflectance for each pixel can be computed from the set of discrete acquisitions and rendered interactively. Currently, the most used mathematical functions that allow this reconstruction from RTI’s acquisitions are Polynomial Texture Mapping (PTM), a method based on Hemispherical Harmonics (HSH) and most recently the Discrete Modal Decomposition (DMD). For these three approaches, a uniform spatial distribution of light sources is an implicit hypothesis. In practice, it is often not possible to achieve this uniform spatial distribution due to intrinsic limitations in systems or in the acquisition conditions. It is then necessary to take into account this nonuniformity in order to avoid artifacts that could alter modelling and subsequent visual rendering. To address this issue, we propose a methodology consisting in the estimation of the local density of the lighting directions used during RTI acquisition. These values are then used to generate a weight for each light position enabling to correct its contribution in the regression performed during the fitting.

Re-Interpretations of Gotlandic Picture Stones Based on the Reflectance Transformation Imaging Method (RTI) : Some Examples