49,874 research outputs found
Analytical treatment and experiments of the virtual image of cone mirrors
No full textWe present the analytical calculation, validated by experiments, of the virtual image of solid cone mirrors used to decipher hidden pictures and/or writings on the plane of the cone’s base. Our results demonstrate that the virtual image of solid cone mirrors lies on a not intuitive 3D surface, thus showing how the commonly used geometric treatment is inadequate to find the correct position of the virtual image. The extension of our analysis to cone mirrors used as panoramic imaging tools for machine vision is discussed
Investigating the color of the blood stains on archaeological cloths: the case of the Shroud of Turin
No full textThe unique reddish blood stains on the archaeological cloth known as the Shroud of Turin caught the attention of several scholars, who proposed different hypotheses to explain the unusual blood color. To date, just a few hypotheses have been tested experimentally, and the results are debatable. In this paper, we test the strength of two hypotheses (namely, the presence of carboxyhemoglobin and the long-term influence of ultraviolet light on high-bilirubin blood) by the spectral reflectance of the blood stained regions on the Shroud and by color analyses of ultraviolet irradiated high-bilirubin blood stains on linen. The relevance of these simple methods to the study of stained textiles is discussed. © 2018 Optical Society of America
Influence of ultraviolet radiation on the color of blood stains embedded in the archaeological textile known as the Shroud of Turin
No full textThe archaeological cloth known as the Shroud of Turin is a controversial object for both scientific and religious reasons. After a brief introduction on the scientific data about the age of the cloth and the microscopic complexity of the images embedded on it, we discuss the unique reddish color of blood stains on the Shroud, which caught the attention of several scholars in the last decades. Various hypotheses were proposed to explain the blood stains reddish color, and the experimental tests produced uncertain results because data were not sufficient or were obtained in vitro. We have tested the strength of two hypotheses, namely, the long term influence of ultraviolet (UV) light on high-bilirubin blood and the presence of carboxyhemoglobin, respectively by RGB color analyses of high-bilirubin blood after irradiation by ns excimer laser pulses and UV lamp and by the study of the spectral reflectance of the blood stains on the Shroud. © 2019 SPIE
Pattern recognition after image processing of low-contrast images, the case of the Shroud of Turin
No full textWe discuss the potentially misleading effect of software techniques for elaborating low-contrast images. In particular, we present the example of the stains embedded into one of the most studied archeological objects in history, the Shroud of Turin. We show for the first time that image processing of both old and recent photographs of the Shroud may lead some researchers to perceive inscriptions and patterns that do not actually exist, confirming that there is a narrow boundary between image enhancement and manipulation. © 2012 Elsevier Ltd. All rights reserved
The interdisciplinary nature of anamorphic images in a journey through art, history and geometry
No full textAnamorphosis is a procedure for drawing an image that appears distorted and indecipherable when seen frontally, the image becoming intelligible only from an eccentric viewpoint or when reflected by a properly designed mirror. In this paper we propose a journey through figurative art, history, psycho-perception and geometry, including a mathematical proof regarding the position of the observation point of anamorphoses. Finally, we discuss applications of anamorphic techniques in encryption, counterterrorism, street art and advertising. Most matter proposed in this paper is suitable for arts educators and offers an interdisciplinary approach to anamorphoses by a creative interaction between different topics, like psychology and figurative arts, geometry and advertising, street art and mathematics
Le immagini anamorfiche in un viaggio interdisciplinare tra arte, storia, geometria e attualità
No full textL’anamorfosi è la tecnica di disegnare un’immagine deforme, incomprensibile se vista frontalmente, che appare ben proporzionata da un punto di vista eccentrico, oppure osservando il suo riflesso da un opportuno specchio curvo. Nel saggio viene proposto un affascinante viaggio fra immagini virtuali, metafore visive e inganni prospettici, riassumendo l’origine, i protagonisti e le tecniche per costruire diversi tipi di anamorfosi. Si incontrano quesiti di psicologia della percezione, di geometria, di storia dell’arte, di prospettiva e di fisiologia della visione. Gli appassionati di matematica possono soffermarsi sui calcoli analitici della mappatura dei disegni anamorfici prospettici e catottrici conici e della posizione del punto di osservazione delle anamorfosi prospettiche. Infine, sono descritte alcune tecniche anamorfiche applicate alla crittografia, all’antiterrorismo, alla pubblicità, alla paesaggistica, all’arte di strada e alla didattica.
Il saggio presenta un approccio multidisciplinare al tema dell’anamorfismo, evidenziando una sorprendente interazione tra argomenti apparentemente distanti, come la geometria e la psicologia, l’ottica e la prospettiva, l’arte di strada e la fisiologia della visione. Lo studio interdisciplinare delle anamorfosi, oltre ad essere facilmente adattabile a scopi didattici e divulgativi, può rappresentare un ponte tra le culture umanistica e scientifica, in un raro esempio di Cultura Totale
Learning intrinsic shape representations via spectral mesh convolutions
No full textWe introduce spectral-based convolutional operators embedded within Generalized Graph Neural Networks (G-GNNs). These operators enable deep learning on graphs through a learnable, energy-driven evolution process. This approach empowers us to impose specific properties on the graph convolutional kernel directly derived from the corresponding variational formulations. Our model incorporates both parameterized and non- parameterized graph Laplacian-based energies within the generalized graph convolutional layer to address features like smoothness, sharpness, and compact support. By making appropriate choices within our G-GNN framework, we pave the way for designing novel paradigms for 3D shape representation, reconstruction, and processing, while also enabling effective feature embeddings for intrinsic neural fields
Participatory development of a soil health monitoring platform with organic farmers communities
No full text
- …
