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(a) Reflectance transformation imaging (RTI) camera and Dome type system (b) RTI Dome system shooting internal image
Source publication
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...
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A large number of murals painted by ancient artists can be seen in various places in Sri Lanka. Always artists set the backgrounds before drawing. They took great care in the architectural features of the temple as well as on the background of the paintings. In the past, they chose different surfaces for the painting and used different types of pla...
Citations
... RTI is applied in diverse environments in the eld of archaeology as a tool to record and reveal manufacture techniques [6][7][8][9][10][11]. Recently, RTI is getting noticed as a practical tool for documentation and evaluating conservation treatments [12][13][14][15]. Many cultural artifacts which have a relatively shallow surface such as documents and paintings have shown outstanding results [16][17][18][19]. Since the early development stage of RTI, ancient coins have been an interesting target for the following reasons. ...
In this paper we present RTI as a documentation tool for visualizing and recording the treatment of coins. RTI, a computational photograph technique based on raking light images, allows interactive re-lighting for vision. Virtual light enhances surface details to examine morphological difference. Stages of conservation treatment were recorded to enhance characteristic features of the relief upon the coin surface and detect and identify weathered characters. Patina removal and consolidation were documented along with the original state. A significant difference in normal and surface texture was observed using RTI viewer and filters. Specular enhancement and normal visualization results were effective for detecting the change of morphology and reflectivity. Characters submersed by thick patina were revealed in Coin 3. Two hidden characters were detected as ‘元’ and ‘訓’. Another illegible character which was previously not regarded as an inscription was discovered. Also, verification of each treatment stage was done to examine whether any foreign material was sufficiently removed. These documentation images indicate that RTI is a promising tool to support manual recording and furthermore allow detection of areas difficult to visualize through the human eye.
Recent progress in the realm of imaging technologies has swiftly disseminated fresh methodologies for representing objects, broadening the horizons for scholars such as art historians, archaeologists, conservators, and conservation scientists. Reflectance Transformation Imaging (RTI) and three-dimensional (3D) modeling via Structure from Motion (SfM) have rapidly gained popularity and are being employed by a wide range of users, expanding the possibilities for understanding objects of material cultural heritage from different perspectives. This paper explores the outcomes achieved through the application of these techniques to gain deeper insights into the surface of a bas-relief within a confined space. This methodology enhanced our understanding of the original sandstone surfaces of the bas-relief by integrating RTI and 3D visualization, thereby acquiring a novel investigative tool with enhanced illumination possibilities. A data fusion approach is proposed using photogrammetry to produce a Virtual RTI (V-RTI). In the case study reported in this paper, focusing on one inner wall of the chapel of Ellesiya at the Museo Egizio of Turin, V-RTI was employed to obtain useful surface information in a context where conventional RTI would have been impossible to achieve. Finally, the study compares the different techniques through direct qualitative and quantitative analysis, highlighting possible future developments from both instrumental and methodological points of view.
The fresco technique appears to have been widely used on Roman mural paintings. The close observation of many of such murals suggests, however, the application of a secco technique over the fresco background. In this work, for the first time, fragments from Pompeian mural paintings that had never been restored have been investigated by optical microscopy, reflectance transformation imaging, micro-Energy-Dispersive X-Ray Fluo-rescence, micro-Fourier Transform Infrared Spectroscopy, and Direct Temperature-resolved Mass Spectrometry. A small number of fragments from restored paintings from the same Archaeological Park was also analyzed by the same techniques for the sake of comparison. The results of this multi-analytical approach that involves-for the first time on this type of samples-scientific photographic investigation, point out to the use of a protein-based medium, most probably egg, to execute the secco layers. On the other hand, wax was ubiquitous in samples taken from restored mural paintings. This last evidence further highlights the importance of selecting appropriate candidates for the study of original organic binders.
Reflectance Transformation Imaging (RTI) is a photography technique that documents object surface relief under varying illumination directions. This article presents the technique through a portable, automated RTI dome system, which allows for convenient photographing of objects in the collection and subsequent rendering of interactive, digital RTI images. The paper showcases the possible applications of RTI methods in documenting books and objects on paper. We discuss the applicability of RTI in four principal areas of interest: technology identification, object condition assessment, evaluation of conservation treatments, and dissemination of conservation work results. Each example is supported with RTI images recorded for objects from the collections of the Jagiellonian Library in Krakow, the Central Archives of Modern Records in Warsaw and the Asia and Pacific Museum in Warsaw.
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.
