Augmented reality application assessment for disseminating rock art

[EN] Currently, marker-based tracking is the most used method to develop augmented reality (AR) applications (apps). However, this method cannot be applied in some complex and outdoor settings such as prehistoric rock art sites owing to the fact that the usage of markers is restricted on site. Thus, natural feature tracking methods have to be used. There is a wide range of libraries to develop AR apps based on natural feature tracking. In this paper, a comparative study of Vuforia and ARToolKit libraries is carried out, analysing factors such as distance, occlusion and lighting conditions that affect user experience in both indoor and outdoor environments, and eventually the app developer. Our analysis confirms that Vuforia¿s user experience indoor is better, faster and flicker-free whether the images are properly enhanced, but it does not work properly on site. Therefore, the development of AR apps for complex outdoor environments such as rock art sites should be performed with ARToolKit.The authors gratefully acknowledge the support from the Spanish Ministerio de Economia y Competitividad to the project HAR2014-59873-R. Similarly, the authors want to express their gratitude to the General Directorate of Culture and Heritage, Conselleria d'Educacio, Investigacio, Cultura i Esport, Generalitat Valenciana for letting us access and carry out research at the archaeological site.Blanco-Pons, S.; Carrión-Ruiz, B.; Lerma, JL. (2018). Augmented reality application assessment for disseminating rock art. Multimedia Tools and Applications. 78(8):10265-10286. https://doi.org/10.1007/s11042-018-6609-xS1026510286788Alahi A., Ortiz R., Vandergheynst P (2012) FREAK: fast retina keypoint. Comput Vis Pattern Recognit 510–517 . doi: https://doi.org/10.1109/CVPR.2012.6247715Amin D, Govilkar S (2015) Comparative study of augmented reality Sdk’S. 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REVISIÓN DE LAS TÉCNICAS DE REALIDAD AUMENTADA Y REALIDAD VIRTUAL EN EL ARTE RUPESTRE

[EN] The usage of augmented reality (AR) and virtual reality (VR) technologies began to grow when smartphones appeared. Until then, the number of portable devices capable of incorporating these technologies was reduced. Video games are the main field where these technologies are applied, but in other fields such as in archaeology, these technologies can offer many advantages. Ruins reconstruction, ancient life simulation, highly detailed 3D models visualisation of valuable objects from the past or even user free movement in missing places are just some examples found in literature. This paper reviews the latest visualisation technologies and their applicability to the rock art field. The main purpose is to disseminate rock art paintings through AR and VR applications. After the image-based three-dimensional (3D) modelling is obtained, an interactive visit to a shelter for displaying rock art paintings is presented. This is one of examples developed in this paper that pretends to apply the revised AR and VR techniques. In addition, an example of AR is developed that can be easily adapted to further applications displaying rock art paintings.[ES] El uso de las tecnologías de realidad virtual (RV) y realidad aumentada (RA) comenzó a crecer con la aparición de los teléfonos inteligentes. Hasta entonces, había pocos dispositivos portátiles capaces de incorporar estas tecnologías. Principalmente estas tecnologías se aplican en la creación de videojuegos, aunque en otros campos como la arqueología, estas tecnologías tienen mucho que ofrecer. Con estas tecnologías es posible mostrar la reconstrucción de ruinas, la simulación de otra época, modelos 3D altamente detallados de objetos de valor del pasado o incluso trasladar al usuario a lugares que ya no existen. Este trabajo presenta una revisión de las últimas tecnologías de visualización y su aplicabilidad en el campo del arte rupestre, con el objetivo de divulgar las pinturas rupestres a través de aplicaciones de RA y RV. Después del modelado 3D basado en imágenes, se presenta una visita interactiva a un refugio para la visualización de las pinturas rupestres. Este es uno de los ejemplos desarrollados en este trabajo que pretende aplicar las técnicas revisadas de RA y RV. Además, se detalla un sencillo ejemplo de RA que puede fácilmente adaptarse a otras aplicaciones que muestren pinturas rupestres.Blanco Pons, S.; Carrión Ruiz, B.; Lerma, JL. (2016). REVIEW OF AUGMENTED REALITY AND VIRTUAL REALITY TECHNIQUES IN ROCK ART. En 8th International congress on archaeology, computer graphics, cultural heritage and innovation. Editorial Universitat Politècnica de València. 176-183. https://doi.org/10.4995/arqueologica8.2016.3561OCS17618

ÁNALISIS DE IMAGEN DIGITAL DE LA REGIÓN VISIBLE MEDIANTE SIMULACIÓN DE PINTURAS DE ARTE RUPESTRE

[EN] Non-destructive rock art recording techniques are getting special attention in the last years, opening new research lines in order to improve the level of documentation and understanding of our rich legacy. This paper applies the principal component analysis (PCA) technique in images that include wavelengths between 400-700 nm (visible range). Our approach is focused on determining the difference provided by the image processing of the visible region through four spectral images versus an image that encompasses the entire visible spectrum. The images were taken by means of optical filters that take specific wavelengths and exclude parts of the spectrum. Simulation of rock art is prepared in laboratory. For this purpose, three different pigments were made simulating the material composition of rock art paintings. The advantages of studying the visible spectrum in separate images are analysed. In addition, PCA is applied to each of the images to reduce redundant data. Finally, PCA is applied to the image that contains the entire visible spectrum and is compared with previous results. Through the results of the four visible spectral images one can begin to draw conclusions about constituent painting materials without using decorrelation techniques.[ES] Las técnicas documentación no destructivas de arte rupestre están recibiendo especial atención en los últimos años, abriendo nuevas líneas de investigación para la mejora del nivel de documentación y comprensión de nuestro patrimonio. Este artículo aplica la técnica de análisis de componentes principales (ACP) en imágenes de longitudes de onda entre 400-700 nm (rango visible). Nuestro enfoque se centra en determinar las diferencias proporcionadas por el procesamiento de imágenes de la región del visible a través de cuatro imágenes espectrales y una imagen que abarca el espectro visible completo. Las imágenes se tomaron con filtros ópticos que recogen longitudes de onda determinadas y excluyen parte del espectro.Se preparó una simulación de pigmentos de arte ruprestre en laboratorio. Para ello se hicieron tres tipos de pigmentos diferentes simulando la composición del material de las pinturas rupestres. Se analizaron las ventajas de estudiar el espectro visible en imágenes separadas. Además, se aplicó ACP a cada una de las imágenes para reducir la información redundante. Finalmente, se realizó ACP a la imagen que abarca todo el espectro visible y se comparó con los resultados anteriores. A través de los resultados de las cuatro imágenes espectrales del visible se pueden sacar conclusiones sobre los materiales que constituyen la pintura sin aplicar técnicas de decorrelación.Carrión-Ruiz, B.; Blanco-Pons, S.; Lerma García, JL. (2016). DIGITAL IMAGE ANALYSIS OF THE VISIBLE REGION THROUGH SIMULATION OF ROCK ART PAINTINGS. En 8th International congress on archaeology, computer graphics, cultural heritage and innovation. Editorial Universitat Politècnica de València. 169-175. https://doi.org/10.4995/arqueologica8.2016.3560OCS16917

Design and implementation of an augmented reality application for rock art visualization in Cova dels Cavalls (Spain)

[EN] Prehistoric rock art paintings, specifically rock-shelters exposed to environmental and anthropogenic factors, are usually faint and severely damaged, being them difficult to identify and understand by visitors. Augmented Reality (AR) supplements reality with virtual information superimposed onto the real world. This sensor-based technology in smartphones/tablets can improve the paintings experience displaying the 2D digital tracings overlapped onto the real scene (rock with faint paintings). This paper presents an AR application (app) developed in Cova dels Cavalls that shows a recreation of a possible original composition full of motifs with descriptive information to improve current guided tour user experiences. This case study aims to evaluate the rock art AR app targeting non-expert visitors as a means of improving rock art knowledge and sensibility of a fragile archaeological UNESCO Work Heritage site. To achieve this, a variety of participants with different backgrounds and interests tested the AR app on site and answered a complete questionnaire about the use of AR mobile apps. Overall, the results showed great acceptance of this AR app, mainly because in addition to adding new information interactively, it helps to identify the rock art motifs, as well as to recognise them quickly, improving their understanding.The authors gratefully acknowledge the support from the Spanish Ministerio de Economia y Competitividad to the project HAR201459873-R. The authors acknowledge the authorisation of the Conselleria d'Educacio, Investigacio, Cultura i Esports the chance to carry out research at this exceptional archaeological site.Blanco-Pons, S.; Carrión-Ruiz, B.; Lerma, JL.; Villaverde, V. (2019). Design and implementation of an augmented reality application for rock art visualization in Cova dels Cavalls (Spain). Journal of Cultural Heritage. 39:177-185. https://doi.org/10.1016/j.culher.2019.03.014S1771853

Principal component analysis of multispectral images applied in rock art field

[EN] This paper tackles principal component analysis (PCA) in images that include wavelengths between 380-1000 nm. Our approach is focussed on taking advantage of the potencial of ultraviolet and infrarred images, in combination with the visible ones, to improve documentation process and rock art analysis. In this way, we want to improve the discrimination between pigment and support rock, and analyse the spectral behaviour of rock art paintings in the ultraviolet and infrared regions. Three images were used, one image from the ultraviolet (UV) region, one from the visible region (VIS) and another one from the near infrared region (NIR). Optical filters coupled to the camera optics were used to take the images. These filters capture specific wavelengths excluding radiation that we are not interested in registering. Finally, PCA is applied to the acquired images. The results obtained demonstrate the PCA usefulness with imagery in this field and also it is possible to extract some conclusions about the correspondent paint pigments.[ES] Este artículo aborda el análisis de componentes principales (ACP) en imágenes de longitudes de onda entre 380-1000 nm. Nuestro enfoque se centra en aprovechar el potencial que las imágenes ultravioletas e infrarrojas ofrecen, en combinación de las visibles, para mejorar la documentación y el análisis de las pinturas rupestres. De este modo, se pretende mejorar el proceso de discriminación entre pigmento y roca soporte, y analizar el comportamiento espectral de las pinturas rupestres en las regiones del ultravioleta e infrarrojo. Para el estudio, se han empleado tres imágenes, una de la región del ultravioleta (UV), una de la región del visible (VIS) y otra de la región del infrarrojo cercano (NIR). Las imágenes se tomaron con filtros acoplados a la óptica de la cámara. Estos filtros captan un rango de longitud de onda y excluyen la radiación que no interesa registrar. Por último, se realiza ACP a las imágenes tomadas. Los resultados obtenidos demuestran la utilidad del ACP en imágenes de este ámbito y también se pueden extraer algunas conclusiones sobre los pigmentos que constituyen la pintura.Los autores agradecen el apoyo del Ministerio de Economía y Competitividad al Proyecto HAR2014-59873-R.Carrión-Ruiz, B.; Lerma García, JL. (2017). Análisis de componentes principales de imágenes multiespectrales en el ámbito del arte rupestre. En Primer Congreso en Ingeniería Geomática. Libro de actas. Editorial Universitat Politècnica de València. 41-47. https://doi.org/10.4995/CIGeo2017.2017.6597OCS414

Color degradation mapping of rock art paintings using microfading spectrometry

[EN] Rock art documentation is a complex task that should be carried out in a complete, rigorous and exhaustive way, in order to take particular actions that allow stakeholders to preserve the archaeological sites under constant deterioration. The pigments used in prehistoric paintings present high light sensitivity and rigorous scientific color degradation mapping is not usually undertaken in overall archaeological sites. Microfading spectrometry is a suitable technique for determining the light-stability of pigments found in rock art paintings in a non-destructive way. Spectral data can be transformed into colorimetric information following the recommendations published by the Commission Internationale de l'Eclairage(CIE). The fading degree can be evaluated through the color changes produced, computing both color and chromatic differences. Microfading Tester (MFT) measurements on spot samples are time-consuming and difficult to materialize on-site. This paper presents the results of statistical Gaussian process interpolation to map the potential MFT spectral variations overtime on a scene full of prehistoric rock art paintings. In addition, a descriptive analysis of color variations that may suffer the rock art motifs overtime has been carried out. The advanced statistical methodology implemented can highlight potential changes on some rock support areas, and stable conditions on the painted red motifs over time, which can help to establish future conservation actions in the archaeological site. (C) 2020 Elsevier Masson SAS. All rights reserved.This research was partially supported by Research and Development Aid Program PAID-01-16 from the Universitat Politècnica de València [FPI-UPV2016 Sub 1 grant].Carrión-Ruiz, B.; Riutort-Mayol, G.; Molada-Tebar, A.; Lerma, JL.; Villaverde, V. (2021). Color degradation mapping of rock art paintings using microfading spectrometry. Journal of Cultural Heritage. 47:100-108. https://doi.org/10.1016/j.culher.2020.10.002S1001084

Augmented Reality Markerless Multi-Image Outdoor Tracking System for the Historical Buildings on Parliament Hill

[EN] Augmented Reality (AR) applications have experienced extraordinary growth recently, evolving into a well-established method for the dissemination and communication of content related to cultural heritage¿including education. AR applications have been used in museums and gallery exhibitions and virtual reconstructions of historic interiors. However, the circumstances of an outdoor environment can be problematic. This paper presents a methodology to develop immersive AR applications based on the recognition of outdoor buildings. To demonstrate this methodology, a case study focused on the Parliament Buildings National Historic Site in Ottawa, Canada has been conducted. The site is currently undergoing a multiyear rehabilitation program that will make access to parts of this national monument inaccessible to the public. AR experiences, including simulated photo merging of historic and present content, are proposed as one tool that can enrich the Parliament Hill visit during the rehabilitation. Outdoor AR experiences are limited by factors, such as variable lighting (and shadows) conditions, caused by changes in the environment (objects height and orientation, obstructions, occlusions), the weather, and the time of day. This paper proposes a workflow to solve some of these issues from a multi-image tracking approach.This work has been developed under the framework of the New Paradigms/New Tools for Heritage Conservation in Canada, a project funded through the Social Sciences and Humanities Research Council of Canada (SSHRC).Blanco-Pons, S.; Carrión-Ruiz, B.; Duong, M.; Chartrand, J.; Fai, S.; Lerma, JL. (2019). Augmented Reality Markerless Multi-Image Outdoor Tracking System for the Historical Buildings on Parliament Hill. 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The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Los grafitos góticos del castillo de Xivert (Alcalà de Xivert, Castellón). Proceso de documentación gráfica y contextualización histórica

En el el año 2012 se descubrieron unos grafitos ejecutados mediante líneas incisas con incrustación de pig- mentación roja en la parte posterior de la muralla de tapial calicostrado de la última fase constructiva del recinto del albacar del castillo de Xivert. En este artículo pretendemos dar cuenta de la posterior consolidación, estudio y documentación de unas manifestaciones artísticas situadas cronológicamente entre el siglo XIII e inicios del XIV, en el periodo de posesión y reforma templaria del castillo andalusí y asociadas al denominado estilo fran- co-gótico.In 2012, graffiti drawings were discovered to have been executed using precise engravings with red pigmented inlays in the posterior part of a lime stucco wall during the final phase of construction in the Albacara enclosure of the castle in Xivert. In this article, we seek to report about of the subsequent consolidation, study, and documentation of these artistic productions chronologically located between the thirteenth century and the beginnings of the fourteenth, in the period of possession and templar reformation of the moorish castle which is associated with the Franco-Gothic style

Los grafitos góticos del castillo de Xivert (Alcalà de Xivert, Castellón). Proceso de documentación gráfica y contextualización histórica

En el el año 2012 se descubrieron unos grafitos ejecutados mediante líneas incisas con incrustación de pig- mentación roja en la parte posterior de la muralla de tapial calicostrado de la última fase constructiva del recinto del albacar del castillo de Xivert. En este artículo pretendemos dar cuenta de la posterior consolidación, estudio y documentación de unas manifestaciones artísticas situadas cronológicamente entre el siglo XIII e inicios del XIV, en el periodo de posesión y reforma templaria del castillo andalusí y asociadas al denominado estilo fran- co-gótico.In 2012, graffiti drawings were discovered to have been executed using precise engravings with red pigmented inlays in the posterior part of a lime stucco wall during the final phase of construction in the Albacara enclosure of the castle in Xivert. In this article, we seek to report about of the subsequent consolidation, study, and documentation of these artistic productions chronologically located between the thirteenth century and the beginnings of the fourteenth, in the period of possession and templar reformation of the moorish castle which is associated with the Franco-Gothic style