Reconstruction and virtual model of the Schickard calculator

Exhibition of objects such as paintings or historical artefacts often involves a common problem: the objects presented are unique, delicate and, therefore, very valuable. On the other hand, these objects should be made accessible to scholars and educators. We present an application of modern 3D computer graphics in the field of reconstructing ancient scientific instruments. The first-four-species calculator of Wilhelm Schickard is made accessible to the public in the World Wide Web using Java 3D.     

Art collections and taste in the Spanish <Emphasis Type="Italic">Siglo</Emphasis><Emphasis Type="Italic">de Oro</Emphasis>

We analyze art pricing in a unique dataset on Madrid inventories between 1600 and 1750. We estimate a price index for the Spanish art market that is used for a general historical analysis of art during this period, showing a large increase in the real price of paintings during the XVII century. Then we examine the price differential between domestic and foreign paintings: At the beginning of the century domestic production was priced substantially below imported paintings, but the price gap was gradually reduced during the century. We argue that such a price convergence was not the fruit of variations in real exchange rate, relative supply or home bias, but was associated with increasing prices for the new domestic painters of the XVII century. Increasing remuneration for painting may have induced artistic innovations by domestic producers and created the conditions for the development of the Siglo de Oro of Spanish art.     

Digital preservation of Brazilian indigenous artworks: Generating high quality textures for 3D models

Three-dimensional (3D) digital preservation aims at generating 3D models of objects that have cultural or scientific value. It allows realistic visualization of objects through virtual museums or scientific applications, and the restoration of the preserved object in case of natural wear or accidents. This work contributes to this research area by presenting a method to improve color texture quality of 3D models obtained from color and depth images of a laser scanner. Although this device offers precise depth information, the resulting color information is still poor and limits the generation of realistic textures. Our approach is to capture photographs of the object with a high-resolution digital camera and use them to generate a new color texture for the 3D model. Our work proposes a practical technique, easy to replicate, to generate high quality textures for 3D models from photographs. The method is composed by three main steps: (1) calibration of the image acquisition devices; (2) data acquisition; and (3) texture generation. In this paper, we detail our color texture generation method and apply it on the digital preservation of many artworks made by native Brazilians (indians) from the Wauja and Karaja communities. These indigenous communities are acknowledged as great ceramic artists, each bearing their own main themes, using a very rich symbolism in their paintings. Their artworks represent important aspects of the native South American culture and their digital preservation is motivated by three main reasons: (1) their fragility; (2) the paintings loose their original appearance with time; and (3) the possibility of extinction of these communities. We present several results of preserved artworks with enhanced quality realistic texture maps. Also, we present a methodology to analyze the quality and accuracy of texture maps. The resulting 3D models can be visualized through a tool we developed to support the virtual exhibit of 3D preserved heritage.     

The Russian avant-garde painting palette: Documentary and physicochemical codification of organic colorants

In the present article an attempt is made to elucidate the organic colorants commonly encountered in the Russian avant-garde painting palette by a combined art historical, documentary and physicochemical investigation, and to examine the influence of environmental factors on the chromatic profile originally sought by the artist. The overall approach based on written sources is confirmed by measurements on relevant paintings. The documentary research deals with the influences of Orthodox iconography, folkloric art, and occidental modernist tendencies on the Russian avant-garde palette, and studies the effects of contradictory historical processes in the chromatic profile of individual paintings. In the experimental section a series of colorants are investigated concerning the effects of accelerated ageing on experimental painting tables, prepared as watercolor and gouache layers on paper ground. The resulting samples are subjected to colorimetric and spectroscopic measurements, and analogous analytical procedures are applied on samples taken from selected paintings. A systematic comparative study of all data permits evaluation of the materials used in terms of their stability towards extrinsic factors, and proposal of degradation routes in order to assist museum curators and conservators in every concrete case related to the broad spectrum of pigments examined.     

ATR-FTIR imaging of albumen photographic prints

The preservation of early 20th century, late 19th century albumen prints is of great concern to collection managers and conservators of photographic materials. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopic imaging is presented for the first time as analytical methodology for the study of albumen photographs. This paper shows the feasibility of obtaining FTIR images of samples from albumen photographs with a high spatial resolution using a Ge ATR objective coupled with an infrared microscope. The improved spatial resolution compared to FTIR images obtained by the reflection method is due to the high refractive index of the ATR crystal, which gives a high numerical aperture and hence, a higher spatial resolution. The technique reveals detailed information on the organic functional group distribution in the individual layers of embedded cross sections and is used complementary to visual microscopy and scanning electron microscopy/energy dispersed X-ray spectroscopy. The main results of the study are discussed with regard to their historical and artistic significance, and they are compared with data from historical and conservation literature.     

Methods and tools for the classification and cataloging of antique moulds from the collection of the Richard-Ginori factory

This study proposes a procedure for digitally classifying and cataloging moulds which belong to the historic collection of the Ginori porcelain factory in Doccia (Sesto Fiorentino, Italy). In addition to a vast number of antique plaster moulds, this collection includes artistic porcelain artifacts obtained from casting porcelain using the moulds and models made of various materials. The proposed methodology includes two workflows: the first starts with photographic and casting processes conducted recently on various groups of moulds and involves historical surveys for investigating the relationships between the various sets of moulds, the models from which they were derived and the porcelain objects derived from them. The second workflow was applied when no information was available for a set of moulds, and involved 3D scanning of the moulds, with virtual reconstruction of the corresponding model followed by a final art historical survey like that used in the first procedure. 3D scanning techniques and successive model reconstruction can also be applied for obtaining a virtual model in the first process, when the physical model was lost, damaged or never existed. The variety and extent of the Ginori collection suggested the use of a customized Data-Base (DB) and a set of functions designed to manage and extract information, data and archived images. This filing system, called DocciaDigitalArchive (DDA), also makes it possible to specify the relationships between the different typology samples (prototype models, moulds derived from them, handmade porcelain objects produced from these moulds), which are associated when the same subject is portrayed. The DB structure conceived also provides the possibility of incorporating pictures and data of known archetypes. This additional information makes it possible to place each subject in its historical and artistic context. For each sample filed in the DDA system, documentary cards, which summarize data, images, reports and links to other entities or samples connected to the subject consulted, can be viewed on a suitable interface.     

The impact of cultural economics on economic theory

The paper asks what kind of impact cultural economics has had on the development of economic theory. Six research areas are discussed: productivity differentials between artistic and non-artistic labor, variations of the public good concept, particularly in relation to environmental goods, endogenous changes in preferences, long-term rates of return on paintings, impact of new media technologies and the autonomy of artistic valuation.It is shown that these topics have relevance beyond their applications in the cultural field, and that the theoretical issues involved challenge standard assumptions and standard modelling procedures in economic theory.Presidential address delivered at the 9th international conference of the Association for Cultural Economics, held in Boston, May 8–11, 1996.     

Assessment of the decision-making process for re-use of a historical asset: The example of Diyarbakir Hasan Pasha Khan,Turkey

The requirements of historical environments that are related to social and economical changes sometimes necessitate the re-use of historical buildings that no longer serve their functions. Deciding how to re-use historical buildings is a difficult problem when the concerns of decision makers are not aligned. This paper proposes a methodology for the appropriate re-use of historical patterns that have lost their original functions and discusses the results of such re-use. Appropriate re-use can result in a sustainable preservation of both historical assets and the environment. Thus, the respectful conversion of structures for new uses based on economic and social needs ensures the authenticity of the structure and of the historical environment. In this study, the historical pattern of Diyarbak?r Hasan Pasha Khan was evaluated through the application of the proposed method. Adaptation of the structure required knowledge of traditional construction techniques. The results reveal that the proposed methodology can be effectively used for historical patterns to prioritise between various re-use criteria. This methodology can be applied in the context of re-use problems and provides solutions for such problems in historical buildings.     

Strontium,a new marker of the origin of gypsum in cultural heritage?

A new possible methodology for recognizing the nature of gypsum in artworks, in particular for wall paintings, was developed. Calcium sulfate can be an alteration product of the calcium carbonate, or a component used by the Artist himself; the problem of identification of the presence and the nature of gypsum could be found detecting the presence of strontium. This element could be used as a marker since, differently from the alteration form, in mineral gypsum simultaneous presence of calcium and strontium occurs. The correlation between these two elements may be recognized using non-invasive in situ X-ray fluorescence measurements. In the present work, we tested this occurrence in various mineral samples of gypsum and alabaster as well in tempera, fresco and Egyptian paintings. Considering the new possible role of strontium indicating the presence of natural gypsum, we expect to provide a valuable tool for conservation scientists, restorers and art historians.     

Contribution of historical Spanish inventions to the knowledge of olive oil industrial heritage

This article presents new research, which has the objective of quantifying the knowledge produced by historical technological innovations in the field of olive oil industrial heritage. It studies inventions related to the mechanical processes of the extraction of olive oil between 1826 and 1966, which are recorded in the Historical Archive of the Spanish Patent and Trademark Office. It uses a new adaptation of the methodology of knowledge management (KM) defined by Nonaka and Takeuchi. We have obtained the knowledge value of each innovation according to the level of technological knowledge registered at the time, while distinguishing between the historical evolution of inventions relating to milling and those relating to pressing. In the first analysis, the results show a recession in the quantitative level of knowledge in the olive oil sector with respect to the technological potential of the time. However, when contrasted with the events relating to industrial heritage at the time, it is possible to account for this technological evolution and prove the validity of the methodology used. The results show that general evolution of the knowledge generated has decreased, particularly in the pressing process, although this is not the case in the milling process.     

Consolidation and protection by nanolime: Recent advances for the conservation of the graffiti,Carceri dello Steri Palermo and of the 18th century lunettes,SS. Giuda e Simone Cloister,Corniola (Empoli)

Nanolime dispersed in 2-propanol was extensively used for the consolidation of wall paintings. The knowledge of the advances of this methodology dealing with all the possible effects associated with the nanolime new material in conservation is fundamental to assess and improve the technique. In this paper, four different dispersions of Ca(OH)₂ nanoparticles were characterised by Small Angle X-rays Scattering technique (SAXS) and Transmission Electron Microscopy (TEM) in order to achieve information on size, shape, polydispersity, agglomeration, and crystal structure (by SAED patterns) of the particles. Once characterised, the dispersions were tested in two different case studies, the Carceri dello Steri in Palermo with their graffiti and the 18th century lunettes at the SS. Giuda e Simone Cloister, Corniola (Empoli) with their lime-based mural paintings. The treated samples were characterised in relationship to either their morphology and surface chemical composition by Scanning Electron Microscopy coupled with Energy Dispersive X-rays spectroscopy (SEM-EDX), or their water absorption and mechanical properties (resistance to material abrasion). The results obtained showed that all the dispersions were nanometrically structured and their application succeeded in recovering the mechanical properties of the painting or graffito layers, not altering their permeability to water and keeping perfectly the wall transpiration. However, the dispersions constituted of the nanoparticles obtained via a synthesis able to control size and shape of the Ca(OH)₂ particles resulted in a better performance in situ, even if the differences found by SAXS and TEM were slight.     

Price Indices for Artists – A Proposal

This paper proposes a price index for artists adjusted for the quality of the paintings, based on the ratio between the average market price and the average pre-sale estimate for paintings. We apply this methodology to a group of selected artists and schools presented in auctions worldwide in the period 1990–2001. A comparison with quality unadjusted and hedonic indices is also conducted.JEL Classification: C10, Z11     

A new class of gels for the conservation of painted surfaces

The application of a new class of organogels as cleaning tools for painted surfaces is described. It combines some of the most attractive features of cleaning liquids and normal gels while diminishing the deleterious characteristics of both. Thus, the ‘latent’ gellant, polyethyleneimine (PEI), reacts with CO₂ at room temperature in solutions of several organic liquids to produce an ammonium carbamate form (PEICO₂). This charged species organizes itself into 3D polymer networks which immobilize the liquids as gels. The properties of the original solution (i.e. a free-flowing liquid) are re-established immediately after addition of a small amount of a weak acid which displaces the CO₂ molecules and makes the PEI chains positively charged. The visual changes are substantiated by rheological analyses. Results from analytical tests to determine the utility of these gels as cleaning tools for painted surfaces of historical and artistic interest, have been obtained from contact angle and FTIR measurements as well as visual comparisons of the surfaces before and after application of the gels. The analyses indicate that the PEICO₂-based organogels were very effective in removing different surface patinas from painted supports. A surface layer of dammar was completely removed from a test canvas with oil paint, an aged painting from the XIX century, and a XV century oil-on-wood panel attributed to Mariotto di Cristoforo. Finally, a surface acrylic polymeric resin (used in a restoration performed during the 1960s) was also successfully removed from Renaissance wall paintings decorating the Santa Maria della Scala Sacristy in Siena, Italy. The isothermally rheoreversible gel approach described in this work represents a new, highly versatile, and very efficient method for removing aged surface patinas from works of art.     

The market for paintings in the Venetian Republic from Renaissance to Rococò

We study the art market in the Venetian Republic from 1550 to 1750 analyzing the determinants of the prices (adjusted for the cost of living measured by the price of wheat) of figurative paintings. Reputation of the painters, size of the paintings and other quantifiable factors affect prices as expected. Other relevant factors include the placement of the paintings (on altars, ceilings or walls), whose impact reflects differences in demand elasticities. We find evidence of the law of one price confirming price equalization between high and low demand geographical destinations and between different subjects. Finally, in a Schumpeterian perspective, we relate the temporal trend of the price of a representative painting with waves of artistic innovations, whose peacks were in the 1500s and in the 1700s with a dark Baroque age in the intermediate century.     

Perpetual options: revisiting historical returns on paintings

This paper applies a perpetual option-pricing model in examining historical returns on paintings. A key development of the paper is formalizing a structural relationship between rational investment decisions and historical returns to art ownership. In this regard the options’ framework yields choice-theoretic implications on the relationship among risk, convenience yields from art ownership, and investor ‘hurdle prices’—prices triggering the purchase and sale of artworks at auction. The methodology offers testable implications concerning the adjustment dynamics in the relationship between historical art returns and risk-free yields. The implications are examined in a case study of paintings of major art schools using error correction methodology. We find evidence of a long-run equilibrium relationship between painting types and risk-free bond yields, and some indication of buyers and sellers preferring exchange environments not prone to “speculative resales.”

Are Multiple Art Markets Rational?

We advance and subsequently test the proposition thatmarkets for fine art are rational, namely, that, inthe determination of price, traders make use of allrelevant art historical and critical information, asrevealed by hedonic content analysis, as well as allinformation on authenticity of the works offered forsale. If true, the proposition has consequences forpublic policy. Museums optimize choices among art historicallysignificant authentic paintings distributed asstochastic rare events in the tertiary market for art. Such paintings have few, if any, art historicallyequivalent substitutes, causing the demand for suchworks of art to be extremely inelastic. Museums tendto buy at the top of the information curve; payingprices which exceed market averages for similar art. As a result, society pays the cost of institutionalrisk aversion. In contrast, collectors often purchaseart before all art historical information is complete,and often earn a reward for assuming a risk due toincomplete information (Singer, 1991; Pomerhene, 1994).Collectors who can borrow to accumulate the highestcategory art can consume the services of their artcollection at zero cost. Stochastic transferfunctions fitted to time series of sales volume at thetwo top international auction houses confirm thehypothesis that the highest category of art is a quasisubstitute for financial instruments (liquid wealth).     

Archeological excavation monitoring using dense stereo matching techniques

Several new tools to obtain three-dimensional information from unorganized image sets are now available for the public use. The main advantage of this software, which is based on dense stereo matching, is the possibility to generate 3D content without the need of high-cost hardware (e.g. 3D scanning devices). Nevertheless, their use in real-world application domains (like cultural heritage) is still not very diffused, due to the non-straightforward usability of the raw data produced. In this paper, we investigate the use of automatic dense stereo reconstruction tools for the monitoring of an excavation site. A methodology for the effective acquisition and processing of data is presented. In addition, the results of the data assessment demonstrate the repeatability of the data acquisition process, which is a key factor when qualitative analysis is performed. The use of three-dimensional data is integrated in an open source mesh processing tool, thus showing that a spatio-temporal analysis can be performed in a very intuitive way using off-the-shelf or free/open digital tools. Moreover, the use of peculiar rendering and the creation of snapshots from arbitrary points of view increase the amount of documentation data, and suggest a perfect integration of data produced with dense stereo matching in the future standard documentation for excavation monitoring.     

Pollution monitoring by dosimetry and passive diffusion sampling for evaluation of environmental conditions for paintings in microclimate frames

Pollutants and their potential degradation of paintings have been measured for the first time in microclimate frames (mc-frames), which are used to protect paintings. The pollutants that were measured include both inorganic pollutants, which originate mainly from external sources, and organic pollutants from mainly internal sources. Those originating from the outdoors enter rooms and subsequently mc-frames at a rate depending on the ventilation rates (air exchange rates) of the mc-frames. The concentration of gaseous pollutants emitted within the mc-frames will depend on net emission rates of the materials used to make the mc-frames, their design, and their ventilation rates. In the EU PROPAINT project measurements of gaseous air pollutants and climatic conditions were performed at various locations both inside and outside different state-of-the-art mc-frames. Diffusive passive pollution gas samplers were used together with different types of dosimeters. Results show that the dosimeters respond to either the photo-oxidizing conditions or the level of volatile organic acids in the environments both in the museums and within the mc-frames. Two dosimeters, the Early Warning Organic (EWO) made from a synthetic polymer and the Resin Mastic coated Piezo electric Quartz Crystals (RM-PQC) respond to photo-oxidation and showed higher values outside than inside the mc-frames. Two other dosimeters, the Glass Slide Dosimeter (GSD) and the Lead coated Piezo electric Quartz Crystals (L-PQC) respond to volatile organic acids and yielded higher values inside than outside the mc-frames. This study emphasizes the need for further work to determine environmental damage functions for paintings, in particular for the effects of organic acids. Such information is essential for the evaluation of the protective effects of mc-frames for paintings. The use of mc-frames is increasing and it is very important to know that this protective measure does not introduce new risks.     

Decision making and cultural heritage: An application of the Multi-Attribute Value Theory for the reuse of historical buildings

The reuse of historical buildings can be seen as a complex decision problem because of the presence of different objectives to be pursued, the public/private nature of the goods under investigation, the existence of several values (historical, artistic, cultural, economic, etc.), the presence of different actors (public government representatives, architects, architectural historians, developers and owners). In decision problems related to the reuse of historical assets conflicts can arise and the availability of analytical frameworks able to support the process is getting more and more important. It has been generally agreed that Multicriteria Decision Analysis (MCDA) can offer a formal methodology to deal with such decision problems, taking into account the available technical information and stakeholders’ values. This paper considers the problem of sustainability assessment in cultural heritage projects using the Multi-Attribute Value Theory (MAVT) approach, which is a particular kind of MCDA technique. Starting from a real case concerning the reuse of historical buildings in the metropolitan area of Torino (Italy), the paper aims at exploring the contribution of MAVT for decision problems in the field of cultural heritage.     

Efficiently capturing large,complex cultural heritage sites with a handheld mobile 3D laser mapping system

Accurate three-dimensional representations of cultural heritage sites are highly valuable for scientific study, conservation, and educational purposes. In addition to their use for archival purposes, 3D models enable efficient and precise measurement of relevant natural and architectural features. Many cultural heritage sites are large and complex, consisting of multiple structures spatially distributed over tens of thousands of square metres. The process of effectively digitising such geometrically complex locations requires measurements to be acquired from a variety of viewpoints. While several technologies exist for capturing the 3D structure of objects and environments, none are ideally suited to complex, large-scale sites, mainly due to their limited coverage or acquisition efficiency. We explore the use of a recently developed handheld mobile mapping system called Zebedee in cultural heritage applications. The Zebedee system is capable of efficiently mapping an environment in three dimensions by continually acquiring data as an operator holding the device traverses through the site. The system was deployed at the former Peel Island Lazaret, a culturally significant site in Queensland, Australia, consisting of dozens of buildings of various sizes spread across an area of approximately 400 × 250 m. With the Zebedee system, the site was scanned in half a day, and a detailed 3D point cloud model (with over 520 million points) was generated from the 3.6 hours of acquired data in 2.6 hours. We present results demonstrating that Zebedee was able to accurately capture both site context and building detail comparable in accuracy to manual measurement techniques, and at a greatly increased level of efficiency and scope. The scan allowed us to record derelict buildings that previously could not be measured because of the scale and complexity of the site. The resulting 3D model captures both interior and exterior features of buildings, including structure, materials, and the contents of rooms.