525 research outputs found
A Construction of the Total Spherical Perspective in Ruler, Compass and Nail
We obtain a construction of the total spherical perspective with ruler,
compass, and nail. This is a generalization of the spherical perspective of
Barre and Flocon to a 360 degree field of view. Since the 1960s, several
generalizations of this perspective have been proposed, but they were either
works of a computational nature, inadequate for drawing with simple
instruments, or lacked a general method for solving all vanishing points. We
establish a general setup for anamorphosis and central perspective, define the
total spherical perspective within this framework, study its topology, and show
how to solve it with simple instruments. We consider its uses both in freehand
drawing and in computer visualization, and its relation with the problem of
reflection on a sphere.Comment: Major revision of the 2015 version, with many changes, including and
a new title. Main results unaltered, but important changes to the
definitions, to notation and organization, and correction of minor errors.
Illustrations revised/added, including a major illustration of spherical
perspective on page 22. Added references to several works previously unknown.
25 pages, 12 figure
PMAS: The Potsdam Multi Aperture Spectrophotometer. II. The Wide Integral Field Unit PPak
PPak is a new fiber-based Integral Field Unit (IFU), developed at the
Astrophysical Institute Potsdam, implemented as a module into the existing PMAS
spectrograph. The purpose of PPak is to provide both an extended field-of-view
with a large light collecting power for each spatial element, as well as an
adequate spectral resolution. The PPak system consists of a fiber bundle with
331 object, 36 sky and 15 calibration fibers. The object and sky fibers collect
the light from the focal plane behind a focal reducer lens. The object fibers
of PPak, each 2.7 arcseconds in diameter, provide a contiguous hexagonal
field-of-view of 74 times 64 arcseconds on the sky, with a filling factor of
60%. The operational wavelength range is from 400 to 900nm. The PPak-IFU,
together with the PMAS spectrograph, are intended for the study of extended,
low surface brightness objects, offering an optimization of total
light-collecting power and spectral resolution. This paper describes the
instrument design, the assembly, integration and tests, the commissioning and
operational procedures, and presents the measured performance at the telescope.Comment: 14 pages, 21 figures, accepted at PAS
Liquid Crystal on Silicon Devices: Modeling and Advanced Spatial Light Modulation Applications
Liquid Crystal on Silicon (LCoS) has become one of the most widespread technologies for spatial light modulation in optics and photonics applications. These reflective microdisplays are composed of a high-performance silicon complementary metal oxide semiconductor (CMOS) backplane, which controls the light-modulating properties of the liquid crystal layer. State-of-the-art LCoS microdisplays may exhibit a very small pixel pitch (below 4 ?m), a very large number of pixels (resolutions larger than 4K), and high fill factors (larger than 90%). They modulate illumination sources covering the UV, visible, and far IR. LCoS are used not only as displays but also as polarization, amplitude, and phase-only spatial light modulators, where they achieve full phase modulation. Due to their excellent modulating properties and high degree of flexibility, they are found in all sorts of spatial light modulation applications, such as in LCOS-based display systems for augmented and virtual reality, true holographic displays, digital holography, diffractive optical elements, superresolution optical systems, beam-steering devices, holographic optical traps, and quantum optical computing. In order to fulfil the requirements in this extensive range of applications, specific models and characterization techniques are proposed. These devices may exhibit a number of degradation effects such as interpixel cross-talk and fringing field, and time flicker, which may also depend on the analog or digital backplane of the corresponding LCoS device. The use of appropriate characterization and compensation techniques is then necessary
Anamorphosis reformed: from optical illusions to immersive perspectives
We discuss a definition of conical anamorphosis that sets it at the foundation of both classical and curvilinear perspectives. In this view, anamorphosis is an equivalence relation between three-dimensional objects, which includes two-dimensional representatives, not necessarily flat. Vanishing points are defined in a canonical way that is maximally symmetric, with exactly two vanishing points for every line. The definition of the vanishing set works at the level of anamorphosis, before perspective is defined, with no need for a projection surface. Finally, perspective is defined as a flat representation of the visual data in the anamorphosis. This schema applies to both linear and curvilinear perspectives and is naturally adapted to immersive perspectives, such as the spherical perspectives. Mathematically, the view here presented is that the sphere and not the projective plane is the natural manifold of visual data up to anamorphic equivalence. We consider how this notion of anamorphosis may help to dispel some long-standing philosophical misconceptions regarding the nature of perspective.info:eu-repo/semantics/publishedVersio
Catoptric Anamorphosis on Free-Form Reflective Surfaces
Lo studio si concentra sulla definizione di una metodologia geometrica per l’impiego dell’anamorfosi catottrica nell’architettura contemporanea. Viene illustrato il particolare fenomeno proiettivo, mostrandone proprietà tipologico-geometriche, rispondenti a meccanismi
di riflessione della luce. Si evidenzia che le esperienze pregresse, nel corso dei secoli, impiegano la tecnica, relegando la realizzazione
esclusivamente a dispositivi riflettenti realizzati da geometrie semplici, a piccola scala e quasi esclusivamente per specchi convessi.
Volendo estendere l’impiego del fenomeno proiettivo e sperimentare le potenzialità espressive su superfici riflettenti di natura geo- metrica complessa free-form, i metodi geometrici tradizionali limitano la progettualità e il controllo preventivo degli esiti, facendo così
venire meno l’effetto desiderato. Si propone, quindi, un processo metodologico generalizzabile di implementazione, definito mediante
l’impiego di procedure algoritmico-parametriche, per la determinazione di immagini deformate, descrivendo possibili sviluppi successivi.The study focuses on the definition of a geometric methodology for the use of catoptric anamorphosis in contemporary architecture.
The particular projective phenomenon is illustrated, showing typological-geometric properties, responding to mechanisms of light reflection.
It is pointed out that previous experience, over the centuries, employed the technique, relegating its realisation exclusively to
reflecting devices realised by simple geometries, on a small scale and almost exclusively for convex mirrors. Wanting to extend the use
of the projective phenomenon and experiment with the expressive potential on reflective surfaces of a complex geometric free-form
nature, traditional geometric methods limit the design and prior control of the results, thus causing the desired effect to fail. Therefore,
a generalisable methodological process of implementation is proposed, defined through the use of algorithmic-parametric procedures,
for the determination of deformed images, describing possible subsequent developments
Beyond Perception: an interaction between graphic design and anamorphosis
Este relatório mostra uma nova forma para, os designers e criadores de conteúdos, apresentarem o seu trabalho e interagirem com o público. Centra-se na criação do efeito anamórfico criado através de software de modelação 3D. O efeito anamórfico é conseguido através da utilização de meios bidimensionais para simular um resultado tridimensional que só pode ser percepcionado de um ponto de vista. Este processo criativo é descrito passo a passo para ajudar outros criativos conseguir esta ilusão, tendo em conta que este relatório se centra apenas na forma de obter o resultado para criar o efeito anamórfico. Outros pontos-chave e terminologia serão mencionados para dar um relatório mais abrangente. Esta ilusão digital pode ser apresentada de várias formas, mas a nossa atenção centrou-se na exploração da sua iteração com um projetor. A este meio de apresentação estão associadas características importantes, tais como: a capacidade de adaptar as imagens a qualquer superfície, a boa mobilidade e o baixo custo. Isto permitiu que as maquetas criadas fossem apresentadas não numa, mas em duas superfícies, o que ajudou este relatório a ser mais exponencial e permitiu uma exploração mais complexa desta técnica do ponto de vista do designer para desenvolver e mostrar exemplos do que poderia ser feito no design de comunicação. Para além destas simulações, são analisados outros exemplos de aplicações reais para demonstrar o que foi feito e o que pode ser alcançado quando existe colaboração entre diferentes áreas que utilizam esta técnica para criar o fator “uau” que a maioria dos criadores de conteúdos e nós, designers, procuramos sempre
Holistic simulation of optical systems
For many years, the design of optical systems mainly comprised a linear arrangement of plane or spherical components, such as lenses, mirrors or prisms, and a geometric-optical description by ray tracing lead to an accurate and satisfactory result. Today, many modern optical systems found in a variety of different industrial and scientific applications, deviate from this structure. Polarization, diffraction and coherence, or material interactions, such as volume or surface scattering, need to be included when reasonable performance predictions are required. Furthermore, manufacturing and alignment aspects must be considered in the design and simulation of optical systems to ensure that their impact is not damaging to the overall purpose of the corresponding setup. Another important part is the growing field of digital optics. Signal processing algorithms have become an indispensable part of many systems, whereby an almost unlimited number of current and potential applications exists. Since these algorithms are an essential part of the system, their compatibility and impact on the completed system is an important aspect to con- sider. In principle, this list of relevant topics and examples can be further expanded to an almost unlimited extend. However, the simulation and optimization of the single sub-aspects do often not lead to a satisfactory result. The goal of this thesis is to demonstrate that the performance prediction of modern optical systems benefits significantly from an aggregation of the individual models and technological aspects. Present concepts are further enhanced by the development and analysis of new approaches and algorithms, leading to a more holistic description and simulation of complex setups as a whole. The long-term objective of this work is a comprehensive virtual and rapid prototyping. From an industrial perspective, this would reduce the risk, time and costs associated with the development of an optical system
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