Cultural Heritage Research Research Articles

Supporting Online and On-Site Digital Diverse Travels

Cultural-heritage research has created a vast amount of information regarding heritage objects and sites. At the same time, recent efforts on the digitization of cultural heritage have provided novel means of documenting tangible cultural resources including digital images, videos, audio testimonies, and 3D reconstructions. Furthermore, ethnographic research is nowadays combined with advanced capturing technologies such as motion capture to record the intangible dimensions of heritage as these are manifested through human expression in dance, heritage crafts, etc. This amount of information is now available and should be used to create novel forms of experiential access to cultural heritage powered by the web and mobile technologies mixed with novel interaction paradigms such as virtual and augmented reality. In this article, a platform is presented that facilitates a cloud-based web application to support location-based narratives on cultural-heritage resources provided through map-based or story-based representation approaches. At the same time, the platform through the power of modern mobile devices can provide these experiences on the move using location-based and image recognition-based augmented reality to facilitate multiple usage contexts. The platform was implemented to support the goal of the project CuRe, in the context of the “Greece-Germany” bilateral collaboration action.

Developing Macro-Raman Mapping as a Tool for Studying the Pigment Distribution of Art Objects.

Raman spectroscopy is a well-appreciated technique in cultural heritage research for its ability to obtain molecular information nondestructively. During Raman mapping experiments, advantage is taken of the excellent spatial resolution of the approach, allowing to visualize the spatial distribution of the molecules. In the current research, macro-Raman mapping is proposed, allowing us to map large areas of an artwork (typically tens or hundreds of square centimeters). Therefore, a new setup is made, using a commercially available mobile Raman spectrometer and fast translation stages. Moreover, the probe is equipped with a triangulator to measure the distance to the surface of the artwork and thus achieving accurate focusing of the Raman probe. Finally, the correct setup is guaranteed by using a calibration module that is designed to allow for spectral calibration and aligning all components of the probe. The use of the method is demonstrated by three cases, where different data processing techniques are illustrated.

Archive Archaeology: Preserving and Sharing Palmyra's Cultural Heritage through Harald Ingholt's Digital Archives. A case study in the accessibility and potential of archives

Despite growing focus, archives remain under-utilised in archaeology and cultural heritage research. Regrettably, COVID-19 exacerbated archive inaccessibility, as researchers were largely cut off from physical resources, thereby underlining the need to develop best practice scenarios. Here we present a case study that demonstrates the potential of archives when made freely available.

PREFACE: PROGRESS AND PROSPECTS OF RESEARCH AND PRACTICE OF DIGITAL CULTURAL HERITAGE

Abstract. Co-hosted by Tsinghua University, ICOMOS China, Tsinghua Heritage Institute for Digitization, and Beijing University of Civil Engineering and Architecture, the CIPA2021 symposium (28th biennial symposium of the international scientific committee for documentation of cultural heritage) was held online successfully at Tsinghua University during August 28th to September 1st, 2021. This is the first time CIPA held a biennial symposium in mainland of China and in online format since its establishment in 1968. The theme of the symposium is “Great Learning & Digital Emotion”. During the 5-day online symposium, opening ceremony & keynote-speech session-1, education session, outstanding youth forum, 12 sub-theme forums, and keynote-speech session-2 & closing ceremony were organized, which included 130 more presentations and attracted more than 1,000 online participants from more than 30 countries on five continents to conduct academic exchanges and seminars.Among all the presentations, four of them are keynote speeches. These include: 1) “deep learning for cultural heritage” by Professor Christian Heipke (President of ISPRS), 2) “space technology in support of world heritage” by Professor Huadong Guo (Academician of Chinese Academy of Sciences), 3) “digital culture heritage and territorial spatial planning — China's practice and perspective” by Professor Jun Chen (Academician of Chinese Academy of Engineering), and 4) “documentation — foundation of any heritage policy” by Professor Teresa Patrício (President of ICOMOS). Besides these keynotes, all other 120 more presentations are selected from the publication papers of ISPRS Annals and Archives.The progress and prospects of research and practice of digital cultural heritage all over the world can be summarized as theory, technology, and method of CHIM that will be described as follows. Basically, CHIM refers of Cultural Heritage Information Modelling. However, based on CIPA2021 symposium and the paper publications, CHIM is not just Modelling and Model, but the current progress and future prospects of digital cultural heritage research and practice, such as “C” represents Collection, Collaboration, Coordination, and Conference; “H” represents High-Speed, High-Quality, High-Tech. and High-Education; “I” represents Integration, Interpret, International, and Intelligent; and “M” represents Multi-Classes, Methodology, Multidisciplinary, and Management. And all of the aspects are included into the following table (see Table 1) and it is clear that CHIM is not only a Model for documentation but also a platform for future intelligent conservation.

PREFACE: PROGRESS AND PROSPECTS OF RESEARCH AND PRACTICE OF DIGITAL CULTURAL HERITAGE

Abstract. Co-hosted by Tsinghua University, ICOMOS China, Tsinghua Heritage Institute for Digitization, and Beijing University of Civil Engineering and Architecture, the CIPA2021 symposium (28th biennial symposium of the international scientific committee for documentation of cultural heritage) was held online successfully at Tsinghua University during August 28th to September 1st, 2021. This is the first time CIPA held a biennial symposium in mainland of China and in online format since its establishment in 1968. The theme of the symposium is “Great Learning & Digital Emotion”. During the 5-day online symposium, opening ceremony & keynote-speech session-1, education session, outstanding youth forum, 12 sub-theme forums, and keynote-speech session-2 & closing ceremony were organized, which included 130 more presentations and attracted more than 1,000 online participants from more than 30 countries on five continents to conduct academic exchanges and seminars.Among all the presentations, four of them are keynote speeches. These include: 1) “deep learning for cultural heritage” by Professor Christian Heipke (President of ISPRS), 2) “space technology in support of world heritage” by Professor Huadong Guo (Academician of Chinese Academy of Sciences), 3) “digital culture heritage and territorial spatial planning — China's practice and perspective” by Professor Jun Chen (Academician of Chinese Academy of Engineering), and 4) “documentation — foundation of any heritage policy” by Professor Teresa Patrício (President of ICOMOS). Besides these keynotes, all other 120 more presentations are selected from the publication papers of ISPRS Annals and Archives.The progress and prospects of research and practice of digital cultural heritage all over the world can be summarized as theory, technology, and method of CHIM that will be described as follows. Basically, CHIM refers of Cultural Heritage Information Modelling. However, based on CIPA2021 symposium and the paper publications, CHIM is not just Modelling and Model, but the current progress and future prospects of digital cultural heritage research and practice, such as “C” represents Collection, Collaboration, Coordination, and Conference; “H” represents High-Speed, High-Quality, High-Tech. and High-Education; “I” represents Integration, Interpret, International, and Intelligent; and “M” represents Multi-Classes, Methodology, Multidisciplinary, and Management. And all of the aspects are included into the following table (see Table 1) and it is clear that CHIM is not only a Model for documentation but also a platform for future intelligent conservation.

Single Image Façade Segmentation and Computational Rephotography of House Images Using Deep Learning

Rephotography is the process of recapturing the photograph of a location from the same perspective in which it was captured earlier. A rephotographed image is the best presentation to visualize and study the social changes of a location over time. Traditionally, only expert artists and photographers are capable of generating the rephotograph of any specific location. Manual editing or human eye judgment that is considered for generating rephotographs normally requires a lot of precision, effort and is not always accurate. In the era of computer science and deep learning, computer vision techniques make it easier and faster to perform precise operations to an image. Until now many research methodologies have been proposed for rephotography but none of them is fully automatic. Some of these techniques require manual input by the user or need multiple images of the same location with 3D point cloud data while others are only suggestions to the user to perform rephotography. In historical records/archives most of the time we can find only one 2D image of a certain location. Computational rephotography is a challenge in the case of using only one image of a location captured at different timestamps because it is difficult to find the accurate perspective of a single 2D historical image. Moreover, in the case of building rephotography, it is required to maintain the alignments and regular shape. The features of a building may change over time and in most of the cases, it is not possible to use a features detection algorithm to detect the key features. In this research paper, we propose a methodology to rephotograph house images by combining deep learning and traditional computer vision techniques. The purpose of this research is to rephotograph an image of the past based on a single image. This research will be helpful not only for computer scientists but also for history and cultural heritage research scholars to study the social changes of a location during a specific time period, and it will allow users to go back in time to see how a specific place looked in the past. We have achieved good, fully automatic rephotographed results based on façade segmentation using only a single image.

How Cultural Heritage Studies Based on Dendrochronology Can Be Improved through Two-Way Communication

A significant part of our cultural heritage consists of wood. Research on historical wooden structures and artefacts thereby provides knowledge of people’s daily lives and the society in which they lived. Dendrochronology is a well-established dating method of wood that can also provide valuable knowledge about climate dynamics, environmental changes, silviculture, and cultural transformations. However, dendrochronology comes with some limitations that end users in cultural heritage sciences must be aware of, otherwise their surveys may not be ultimately performed. We have drawn attention to studies in which dendrochronological results have been misinterpreted, over-interpreted, or not fully utilized. On the other hand, a rigorous dendrochronological survey may not respond to the request of information in practice. To bridge this rigour-relevance gap, this article has considered and reviewed both the dendrochronology’s science-perspective and the practitioner’s and end user’s call for context appropriate studies. The material for this study consists of (i) interviews with researchers in dendrochronology and end users represented by cultural heritage researchers with focus on building conservation and building history in Sweden, and (ii) a review of dendrochronological reports and the literature where results from the reports have been interpreted. From these sources we can conclude that a continuous two-way communication between the dendrochronologists and end users often would have resulted in improved cultural heritage studies. The communication can take place in several steps. Firstly, the design of a sampling plan, which according to the current standard for sampling of cultural materials often is required, is an excellent common starting point for communication. Secondly, the survey reports could be developed with a more extensive general outline of the method and guidance in how to interpret the results. Thirdly, the potential contribution from dendrochronology is often underused, foreseeing historical information on local climate, silviculture, and choice of quality of the wooden resource, as the focus most often is the chronological dating. Finally, the interpretation of the results should consider all the available sources where dendrochronology is one stake for a conciliant conclusion.

Preliminary Investigation into Accelerators for In-Situ Cultural Heritage Research

Preliminary Investigation into Accelerators for In-Situ Cultural Heritage Research

The Study of Three-Dimensional Fingerprint Recognition in Cultural Heritage

Fingerprints play a central role in any field where person identification is required. In forensics and biometrics, three-dimensional fingerprint-based imaging technologies, and corresponding recognition methods, have been vastly investigated. In cultural heritage, preliminary studies provide evidence that the three-dimensional impressions left on objects from the past (ancient fingerprints) are of paramount relevance to understand the socio-cultural systems of former societies, to possibly identify a single producer of multiple potteries, and to authenticate the artist of a sculpture. These findings suggest that the study of ancient fingerprints can be further investigated and open new avenues of research. However, the potential for capturing and analyzing ancient fingerprints is still largely unexplored in the context of cultural heritage research. In fact, most of the existing studies have focused on plane fingerprint representations and commercial software for image processing. Our aim is to outline the opportunities and challenges of digital fingerprint recognition in answering a range of questions in cultural heritage research. Therefore, we summarize the fingerprint-based imaging technologies, reconstruction methods, and analyses used in biometrics that could be beneficial to the study of ancient fingerprints in cultural heritage. In addition, we analyze the works conducted on ancient fingerprints from potteries and ceramic/fired clay sculptures. We conclude with a discussion on the open challenges and future works that could initiate novel strategies for ancient fingerprint acquisition, digitization, and processing within the cultural heritage community.

An emotions-informed approach for digital documentation of rural heritage landscapes: Baojiatun, a traditional tunpu village in Guizhou, China

The application of digital technologies has greatly improved the efficiency of cultural heritage documentation and the diversity of heritage information. Yet the adequate incorporation of cultural, intangible, sensory or experimental elements of local heritage in the process of digital documentation, and the deepening of local community engagement, remain important issues in cultural heritage research. This paper examines the heritage landscape of tunpu people within the context of digital conservation efforts in China and the emergence of emotions studies as an evaluative tool. Using a range of data from the Ming-era village of Baojiatun in Guizhou Province, this paper tests an exploratory emotions-based approach and methodology, revealing shifting interpersonal relationships, experiential and praxiological engagement with the landscape, and emotional registers within tunpu culture and heritage management. The analysis articulates distinctive asset of emotional value at various scales and suggests that such approaches, applied within digital documentation contexts, can help researchers to identify multi-level heritage landscape values and their carriers. This methodology can provide more complete and dynamic inventories to guide digital survey and representation; and the emotions-based approach also supports the integration of disparate heritage aspects in a holistic understanding of the living landscape. Finally, the incorporation of community participation in the process of digital survey breaks down boundaries between experts and communities and leads to more culturally appropriate heritage records and representations.

The Galileo Museum and the digital world

The Galileo Museum has been on the digital path for about thirty years in the belief that information technology is an indispensable tool for the scientific research and enhancement of cultural heritage. This essay illustrates some applications that show the state of the art of the initiatives undertaken by this institution in the field of digitization. In particular, we present two thematic digital libraries conceived as environments for research and scientific exchange between scholars, and two virtual exhibitions or, better, digital explorations of historical documents that are difficult to read and interpret.

Use of Tools

The technology supporting Interactive Digital Narrative (IDN) is of particular significance to cultural heritage research. IDN technology provides a means of engagement in cultural heritage sites, a medium for culturally significant stories, and culturally significant story-centric games. While previous work in this space has numerous examples of user experience (UX) evaluations of the interactive narrative works themselves, there is significantly less in terms of evaluation of technology for authoring IDN, creating a UX research space in this area that is focused on the audience and not authors. We propose to balance this focus by considering the UX of authoring tools more closely. In this work, we undertake a review of the state of the art of authoring tools for IDN, such as story-centric games, and report on a rigorous UX evaluation of representative technologies (n = 21). We also address the challenges of UX research for these tools through an original evaluation methodology where authors complete a story composed of representative story features. Our study leads us to conclude seven UX principles for IDN authoring tools that explore both how authors use tools to create story-focused games and how the interface for these tools impacts the creative process.

The role of cultural heritage in visitor narratives of peatlands: analysis of online user-generated reviews from three peatland sites in England

ABSTRACT User-generated reviews of visitor attractions, on publicly available websites, such as Tripadvisor, are frequently used in tourism research but feature less often in published cultural heritage research. In this paper, we describe a qualitative analysis of the text from user-generated reviews of three peatland heritage landscapes in the United Kingdom – Ilkley Moor, Thorne and Hatfield Moors, and Shapwick Heath – to better understand the role tangible and intangible cultural heritage play in visitor perceptions and narratives of these sites. Our analysis indicates that visitors tend to emphasise natural over cultural heritage of peatland landscapes and hold plural, highly contextual and sometimes dissonant perceptions; there is no single story of peatlands. This presents both challenges and opportunities for building public appreciation of peatland cultural heritage. User-generated reviews offer, as-yet under-explored, potential data for use by heritage researchers and managers who seek to explore how visitors understand and use sites, and may also contribute to the emerging intangible heritage of heritage landscapes.

In situ Raman spectroscopy for cultural heritage studies

AbstractRaman spectroscopy is considered as one of the most appreciated analytical techniques in the cultural heritage research field, thanks to some of its favourable characteristics such as the relatively quick time of analysis, identification of both inorganic and organic molecules. The necessity of conducting the research non‐destructively on‐site and directly on the artefact brought the technique out of the laboratory. Since 2004, when the first non‐commercial mobile Raman instrument for in situ applications on cultural heritage objects was realized, years of continuous technical and instrumental developments have passed. Today, on‐site Raman spectroscopy is considered as a cornerstone technique for the documentation of materials of works of art and the assessment of their conservation state without jeopardizing the integrity of the artefact. This paper reviews some of the breakthroughs of Raman analysis of cultural heritage objects, conducted on field (museum environment, outdoors and archaeological complexes).

Application of Terrestrial Laser Scanning for the Inventory of Historical Buildings on the Example of Measuring the Elevations of the Buildings in the Old Market Square in Jarosław

Terrestrial laser scanning (TLS) technology is increasingly used in surveying, construction and architecture. The potential of the data obtained by this method creates the possibility of its versatile application also in conservation and revitalization of monuments, archaeology or history. The use of this technology during the creation of architectural documentation of a historic building greatly facilitates the acquisition of comprehensive information about its actual condition in a fast, non-invasive and very precise manner. Thanks to digital technology, it also creates the possibility to accurately interpret the condition of an object and present its model in a virtual space. This technology provides the ability to transfer acquired image elements with high accuracy of their mapping to plans and designs prepared by architects and contractors. It is also possible to maintain high technical standards in the processes aimed at the preparation of the required graphical studies, thanks to the use of the point cloud obtained in TLS. One of the most important advantages of using this measurement method is the possibility of combining it with data from e. g. from photogrammetric tools, which gives the possibility to fill in the missing elements creating a more complete picture of the needed data. This paper presents the implementation of terrestrial laser scanning technology as a non-invasive method for the modelling of walls and buildings of the so-called “greenfield”. Revers BIM on the example of the measurement of the facades of the buildings of the old market in Jarosław. This technology allows for preparation of precise architectural documentation including: projections, sections, elevation views, 3D models or multimedia visualizations. The use of TLS for cultural heritage research also enables the preparation of fully complete documentation for conservation and restoration works aimed at maintaining the current state of monuments or even at reconstructing their damaged architectural elements.

Tourism and Guidebooks in the Activities of Academic Staff at the Faculty of Fine Art at Stefan Batory University in Vilnius

Stefan Batory University in Vilnius was established in 1919 as a regional entity to carry out scientific research and develop Polish academic education. One of its faculties – the Faculty of Fine Arts (1930–1939) – gathered charismatic and popular artists, historians and architects. Among them, two professors – Juliusz Kłos (1888–1933) and Marian Morelowski – published the guidebooks for Vilnius and Wileńszczyzna region (Wilno. Przewodnik krajoznawczy, 1937; Zarys sztuki wileńskiej z przewodnikiem po zabytkiem między Niemnem a Dźwiną, 1939). The book written by Kłos gained popularity and was often purchased by the tourists who visited Vilnius. The aim of the article is to determine the main methodology, historical approaches and working styles of both authors. Moreover, the paper involves their attitude towards developing tourism, cultural heritage and historical research. The article also involves the main ideas of artistic education professors had and how much tourism was involved in the whole education process for them.

Revealing time\u2019s secrets at the National Theatre of Costa Rica via innovative software for cultural heritage research

Establishing affordable, efficient, accessible, innovative, and multidisciplinary methodologies to the diagnosis of the conservation state of an artwork is key to carry out appropriate strategies of conservation and consequently to the creation of modern public policies on cultural heritage. Limited access to large-format paintings is a challenge to restoration scientists seeking to obtain information quickly, in a non-destructive and non-invasive manner, and identify regions of interest. Therefore, we put forward two unique software tools based on multispectral imaging techniques, with the long-term aim to assess the artist’s intentions, creative process, and colour palette. This development paves the way for a comprehensive and multidisciplinary understanding of the mysteries encompassed in each pictorial layer, through the study of their physical and chemical characteristics. We conducted the first ever study on Musas I and Musas II, two large-format paintings by Italian artist Carlo Ferrario, located in the National Theatre of Costa Rica. In this study, we used our novel imaging techniques to choose regions of interest in order to study sample layers; while also assessing the works’ state of conservation and possible biodeterioration. We explored the applications of our two versatile software tools, RegionOfInterest and CrystalDistribution, and confirmed paint stratigraphies by means of microscopy and spectroscopy analyses (OM, SEM-EDX, Fluorescent microscopy, FTIR-ATR and micro-Raman). In a pilot study, we identified the artist’s main colour palette: zinc white, lead white, chrome yellow, lead read, viridian, along with artificial vermilion and ultramarine pigments. We were able to identify artificial vermilion and ultramarine and distinguish them from the natural pigments using CrystalDistribution to map the average size and diameter of the pigment crystals within the paint layers. This study demonstrated that software-based multidisciplinary imaging techniques are novel in establishing preventive and non-invasive methods for historical painting conservation studies, in addition, this study provides tools with great potential to be used in the future in applications such as virtual restoration.

Standards and quantification of coin iconography: possibilities and challenges

Abstract The use of digital technologies and big data in the humanities and social sciences provided many opportunities for cultural heritage management and research, enabling data sharing and interdisciplinary collaborations. These developments increased the need for standardized data formats. General and domain-specific standards for describing and classifying cultural data, based on linked data principles, are developed to support increasingly numerous digital collections. However, the existing standards do not fully address the particular challenges concerning the standardized descriptions of images. Here we focus on ancient coins, an official image-bearing medium. We present current approaches to coin iconography, including the application of statistical measures to infer patterns in the use of images for communication. We discuss the importance of consistent, standardized data for quantitative research, and propose a generalized approach, focused on basic concepts and limiting the level of detail for the sake of simplicity, interoperability, and compatibility with statistical methods, as a necessary first step towards creating reliable iconographic standards.

Research on Convolutional Neural Network-Based Virtual Reality Platform Framework for the Intangible Cultural Heritage Conservation of China Hainan Li Nationality: Boat-Shaped House as an Example

Hainan is located at the southernmost tip of China, since ancient times it has always occupied an important position on the Silk Road. Hainan culture is dominated by minority and marine cultures and has a rich intangible cultural heritage. Hainan has always been committed to the development and utilization of its wide cultural heritage, and the development direction is mainly based on live display and folk activities. In May 2020, the Chinese government announced the establishment of the Hainan Free Trade Port Policy and System, the establishment of a Hainan International Free Trade Zone, and the development of tourism, modern services, and high-tech industry. All these put forward higher requirements for the protection of Hainan’s cultural heritage, not just traditional ways to protect and promote, but also to use the dividends of current scientific and technological development to keep up with the times to protect and promote. The integration of digital technology will be the development direction of cultural heritage and intangible cultural heritage. This paper enumerates and analyzes other cases and academic directions of intangible cultural heritage, combined with the present situation of intangible cultural heritage in Hainan. It also analyzes the predicament of handiwork inheritance in Hainan intangible cultural heritage, expounds the structure, humanistic connotation, and construction skills of Li nationality ship house, and summarizes the role of a novel deep learning convolutional neural network- (CNN-) based virtual reality framework of intangible cultural heritage conservation in promoting the intangible cultural heritage of traditional skills. It also puts forward the scheme and heritage conservation virtual reality content construction and provides the process of building a virtual reality platform for the intangible cultural heritage of ship-shaped houses, which as an example can be used as a reference for intangible cultural heritage researchers in other areas. At the same time, it fills the gap for the artificial intelligence-based digitization of the intangible cultural heritage.

Application of Infrared Reflectance Spectroscopy on Plastics in Cultural Heritage Collections: A Comparative Assessment of Two Portable Mid-Fourier Transform Infrared Reflection Devices.

Plastics have been increasingly used to create modern and contemporary art and design, and nowadays, museum collections hold numerous objects completely or partially made of plastics. However, the preservation of these materials is still a challenging task in heritage conservation, especially because some plastics show signs of degradation shortly after their production. In addition, different degradation mechanisms can often take place depending on the plastic composition and appropriate environmental and packaging conditions should be adopted. Therefore, methods for in situ and rapid characterization of plastic artifacts' composition are greatly needed to outline proper conservation strategies. Infrared (IR) spectroscopy, such as attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR), is a well-established method for polymeric material analysis. However, ATR FT-IR requires an intimate contact with the object, which makes its application less appropriate for the in situ investigation of fragile or brittle degraded plastic objects. Mid-FT-IR reflectance spectroscopy may represent a valid alternative as it allows in situ measurements with minimum or even no contact, and IR data can be acquired rapidly. On the other hand, spectral interpretation of reflectance spectra is usually difficult as IR bands may appear distorted with significant changes in band maximum, shape, and relative intensity, depending on the optical properties and surface texture of the material analyzed. Presently, mid-FT-IR reflection devices working in external reflection (ER FT-IR) and diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) modes have been used in cultural heritage research studies. As the collected vibrational information depends on the optical layout of the measuring system, differences between ER FT-IR and DRIFT spectra are thus expected when the same polymer is analyzed. So far, ER FT-IR and DRIFT spectroscopy have been individually explored for the identification of plastic objects, but comparative studies between the application of two reflectance FT-IR modes have not been presented yet. In this work, the use of two portable FT-IR spectrometers equipped with ER FT-IR and DRIFTS modes were compared for plastics identification purposes for the first time. Both references of polymeric materials and historical plastic objects (from a Portuguese private collection) were studied and the differences between ER FT-IR and DRIFT spectra were discussed. The spectra features were examined considering the two different optical geometries and analytes' properties. This new insight can support a better understanding of both vibrational information acquired and practical aspects in the application of the ER FT-IR and DRIFTS in plastic analysis.