Light Rays Research Articles

Implementing Many-Lights Rendering with IES-Based Lights

In recent years, many research projects on real-time rendering have focused on the introduction of global illumination effects in order to improve the realism of a virtual scene. The main goal of these works is to find a compromise between the achievable quality of the resulting rendering and the intrinsic high computational cost of global illumination. An established approach is based on the use of Virtual Point Lights, i.e., “fictitious” light sources that are placed on surfaces in the scene. These lights simulate the contribution of light rays emitted by the light sources and bouncing on different objects. Techniques using Virtual Point Lights are often called Many-Lights techniques. In this paper, we propose an extension of a real-time Many-Lights rendering technique characterized by the integration of photometric data in the process of Virtual Point Lights distribution. We base the definition of light sources and the creation of Virtual Point Lights on the description provided in the IES standard format, created by the Illuminating Engineering Society (IES).

A precise compensation algorithm for visual measurement in non-uniform refractive index environment based on Hamiltonian ray tracing method

In complex large-scale industrial environments, light rays no longer propagate in a straight line due to the influence of non-uniform refractive index, which will lead to large measurement errors in visual measurement. In order to accurately compensate the error, this paper firstly quantitatively analyzes the influence of non-uniform refractive index distribution on visual measurement. Then the symplectic matrix ray-tracing method of Hamiltonian optics is used to reconstruct spatial light in the reverse direction with known light propagation end point and spatial refractive index distribution. Thus the traditional model of light propagation along a straight line in visual measurement can be changed and the measurement error introduced by non-uniform refractive index field can be corrected. Finally, the proposed Hamiltonian ray tracing method was verified through the spatial non-uniform refractive index field reconstructed by Background Oriented Schlieren(BOS) method. The experimental results verified the effectiveness and feasibility of this method.

Leaf anatomy affects optical properties and enhances photosynthetic performance under oblique light.

Photosynthesis under oblique illumination has not been studied extensively despite being the prevailing light regime under natural conditions. We studied how photosynthetic rate (An) is affected by the geometrical arrangement between leaf lamina and light rays, in conjunction with key anatomical features; studied plant species selected based on the absence (homobaric) or the occurrence of bundle sheath extensions (BSEs; heterobaric) and the arrangement of these structures, that is, parallel (monocots) or reticulated (dicots). The direction of light ray affected leaf absorptance (Abs) and An; both were maximal when the angle of incidence of light on leaf surface (polar angle, θ) was 90°. For any lower θ, both Abs and An were higher when the angle between the leaf axis and the light rays (azimuthal angle, φ) was zero. The dependence of Abs and An from φ was only evident in monocots and, especially, in heterobaric compared to homobaric leaves. In some species, An was substantially higher than predicted from calculated photon flux density of oblique light. The occurrence of BSEs, especially in monocots, significantly alters leaf optical properties, resulting in more efficient photosynthesis under oblique illumination conditions.

Changes in peripheral visual field perception after intraocular lens implantation

Aims/Purpose: To assess whether the eccentricity of the perception of objects in the peripheral visual field changes when a crystalline lens is replaced by an intraocular lens (IOL).Methods: The effect of the IOL on the eccentricity at which peripheral objects are perceived was assessed using phakic and pseudophakic versions of the same eye model. Non‐sequential ray tracing simulations were used to determine the relation between the input eccentricity at which an object was positioned in the visual field and the corresponding eccentricity at which the object was perceived by the eye in every eye model. Two different IOL designs were evaluated in the pseudophakic eye model. For each IOL design five different axial positions and seven different intrinsic powers were tested. Subsequently, the results of the pseudophakic eye models were compared to the results of the phakic model.Results: For central vision, the perceived eccentricity differed less than 1 degree between the phakic and pseudophakic models. For peripheral vision, the light rays were refracted to a more central retinal location in pseudophakic eyes than in phakic eyes, therewith shifting perceived eccentricity. The amount of the perceived shift depended on the IOL design and its axial position. The maximal shift within the evaluated pseudophakic models was 5.4 degrees towards central vision.Conclusions: IOL implantation has a minor effect on how the central visual field is perceived, but it can alter the eccentricity at which objects in the peripheral visual field are perceived by over 5 degrees. Such a shift in eccentricity can, for instance, affect how peripheral visual complaints, such as negative dysphotopsia, are experienced.

Anatomical and optical origins of negative dysphotopsia

Negative dysphotopsia (ND) is a complaint after, an otherwise uneventful, cataract surgery with intraocular lens (IOL) implantation. It is generally described as a shadow in the temporal peripheral visual field. Approximately 3% of the patients suffer from this condition and complaints range from mild visual field defects to a significant loss of peripheral vision that disturbs daily life. Originally, this condition was poorly understood as conventional ophthalmic techniques are not designed for a comprehensive evaluation of the peripheral vision. In the last years, however, a combination of dedicated anatomical measurements and optical ray tracing simulations have revealed the cause of ND and proposed different treatments.In this presentation the basic principles of ray tracing of the eye will be presented, followed by the main results of the ESCRS vRESPOND study. In this study, a detailed anatomical assessment of the pseudophakic population with and without ND was made. The distinct differences between both groups, such as a smaller (p = <0.01) and more decentered (p < 0.01) pupil and an increased temporal‐tilted iris (p < 0.01), will be discussed. Interestingly, high‐resolution ocular MRI revealed that the in‐the‐bag IOL position and retinal shape did not differ significantly between both groups. The impact of these differences on the patient's peripheral vision will be shown through ray tracing simulations. First the optical origin of the shadow, caused by light rays missing the IOL, will be presented, followed by a quantitative analysis of the effect the different anatomical and IOL‐design parameters on the severity of this shadow. At the end of the presentation, the optical rationale behind some of the treatments of ND will be discussed.

Toward Blind Flare Removal Using Knowledge-Driven Flare-Level Estimator.

Lens flare is a common phenomenon when strong light rays arrive at the camera sensor and a clean scene is consequently mixed up with various opaque and semi-transparent artifacts. Existing deep learning methods are always constrained with limited real image pairs for training. Though recent synthesis-based approaches are found effective, synthesized pairs still deviate from the real ones as the mixing mechanism of flare artifacts and scenes in the wild always depends on a line of undetermined factors, such as lens structure, scratches, etc. In this paper, we present a new perspective from the blind nature of the flare removal task in a knowledge-driven manner. Specifically, we present a simple yet effective flare-level estimator to predict the corruption level of a flare-corrupted image. The estimated flare-level can be interpreted as additive information of the gap between corrupted images and their flare-free correspondences to facilitate a network at both training and testing stages adaptively. Besides, we utilize a flare-level modulator to better integrate the estimations into networks. We also devise a flare-aware block for more accurate flare recognition and reconstruction. Additionally, we collect a new real-world flare dataset for benchmarking, namely WiderFlare. Extensive experiments on three benchmark datasets demonstrate that our method outperforms state-of-the-art methods quantitatively and qualitatively.

Learning Kernel-Modulated Neural Representation for Efficient Light Field Compression.

Light fields capture 3D scene information by recording light rays emitted from a scene at various orientations. They offer a more immersive perception, compared with classic 2D images, but at the cost of huge data volumes. In this paper, we design a compact neural network representation for the light field compression task. In the same vein as the deep image prior, the neural network takes randomly initialized noise as input and is trained in a supervised manner in order to best reconstruct the target light field Sub-Aperture Images (SAIs). The network is composed of two types of complementary kernels: descriptive kernels (descriptors) that store scene description information learned during training, and modulatory kernels (modulators) that control the rendering of different SAIs from the queried perspectives. To further enhance compactness of the network meanwhile retain high quality of the decoded light field, we propose modulator allocation and apply kernel tensor decomposition techniques, followed by non-uniform quantization and lossless entropy coding. Extensive experiments demonstrate that our method outperforms other state-of-the-art (SOTA) methods by a significant margin in the light field compression task. Moreover, after adapting descriptors, the modulators learned from one light field can be transferred to new light fields for rendering dense views, showing the potential of the solution for view synthesis.

Interactive Design and Optics-Based Visualization of Arbitrary Non-Euclidean Kaleidoscopic Orbifolds.

Orbifolds are a modern mathematical concept that arises in the research of hyperbolic geometry with applications in computer graphics and visualization. In this paper, we make use of rooms with mirrors as the visual metaphor for orbifolds. Given any arbitrary two-dimensional kaleidoscopic orbifold, we provide an algorithm to construct a Euclidean, spherical, or hyperbolic polygon to match the orbifold. This polygon is then used to create a room for which the polygon serves as the floor and the ceiling. With our system that implements Möbius transformations, the user can interactively edit the scene and see the reflections of the edited objects. To correctly visualize non-Euclidean orbifolds, we adapt the rendering algorithms to account for the geodesics in these spaces, which light rays follow. Our interactive orbifold design system allows the user to create arbitrary two-dimensional kaleidoscopic orbifolds. In addition, our mirror-based orbifold visualization approach has the potential of helping our users gain insight on the orbifold, including its orbifold notation as well as its universal cover, which can also be the spherical space and the hyperbolic space.

Tiling billards on triangle tilings, and interval exchange transformations

AbstractWe consider the dynamics of light rays in triangle tilings where triangles are transparent and adjacent triangles have equal but opposite indices of refraction. We find that the behavior of a trajectory on a triangle tiling is described by an orientation‐reversing three‐interval exchange transformation on the circle, and that the behavior of all the trajectories on a given triangle tiling is described by a polygon exchange transformation. We observe that, for a particular choice of triangle tiling, certain trajectories appear to approach the Rauzy fractal, under rescaling.

Comparative analysis of Family Laws in Pakistan and Islamic Injuctions in this Regard

“No ination can ever be worthy of its existence that cannot take its women along with the men.” Mohammad Ali Jinnah, Founder of Pakistan” (Russell & Catharine, 2007).The legal status of Muslim women, especially in family relations, has been the subject of considerable international academic and media interest. The right to marital freedom is a constitutional right in Pakistan and demonstrates that in ia country in which women’s rights are notoriously and brutally violated, female divorce rights stand as a ray of light amidst the “darkness” of ithe igeneral legal status of Pakistani women. Contrary to the conventional wisdom construing Islamic law as opposed to women’s rights, the constitutionalization of Islam in Pakistan has proven to be a potent tool in the service of women’s interests.

Clinical Relationship of Blood Vitamin-C Levels and Age Related Cataract

Abstract: Background: Cataract is an extremely important and ground source of the curable blindness around the globe. Lenticular Vitamin C is actual important ultraviolet filter and antioxidant that decreases entry of the light rays into lens and therefore preventing the lens from oxidative damage. Keeping this in sight, higher intake of the vitamin c and by consuming the diet rich in vitamin c can prevent the age-related cataract. The motive of this study is to analyze if high vitamin C levels can lead to decrease in the percentage of cataract in patients. Objective: To determine occurrence of the senile cataract among Vitamin C deficient subjects and compare mean vitamin C levels among senile cataract and controls. Materials and Methods: This comparative cross-sectional study was conducted at The Department of Ophthalmology, PIMS (Pakistan Institute of Medical Sciences), Islamabad, Pakistan, after being accepted by Ethical review Committee. Individuals were selected, in the age range between 45 to 75 years of age from the patients who visited Eye OPD, PIMS, and Islamabad. All participants undergone detailed ophthalmic examination that included visual acuity assessment through the Snellen’s chart, anterior segment examination on the slit lamp. Blood vitamin C level was assessed in both cases and controls. Information was recorded in the designated Proforma and data was analyzed using SPSS 23.0 version. Results: We enrolled 100 patients 50 in each group. Average age of our individuals in our case set was 60.96±9.57 years and in control set remained 59.66±8.92 years. In study group 25(50.0%) remained male and 25(50.0%) remained female. similarly, in control group 19(38.0%) were male and 31(62.0%) were female. The mean value of level of serum vitamin C in study group was 0.55±0.06 mg/dl and average value of level of the serum vitamin C in control group was 0.87±0.07 mg/dl. There was significant difference as p value is less than level of implication (p < 0.05). In cataractous individuals the level of the serum vitamin C was low as compared to control set. Conclusion: In this study, researchers determined that blood vitamin C may be a preventive component towards cataract development that is likely influenced by vitamin C consumption.

Analysis of the Use of Optical Waves in the World of Health: Literature Study

Waves are vibrations that propagate at any time. Waves are divided into two, namely mechanical waves and electromagnetic waves. In the world of health, what we often encounter are tools whose use is accompanied by one of the physics concepts, namely optical waves. Optical waves in the world of health are very important to apply because they are the basis for learning in health science or in the sense that the concepts that are developed in health science use the concept of optical waves. Optical waves are known as electromagnetic waves, because these waves describe visible light rays, infrared, and ultraviolet rays, so these rays are used as materials for the use of optical instruments. There are many kinds of optical instruments, including loupes which are used to magnify small things, microscopes as a tool to see objects that are far away with the sense of sight, binoculars as a tool to see the distance of objects that are far from the surface of the earth, and the eye as a tool for our vision. Then scientists applied the wave concept with optical tools to serve as a reference in the world of health. Waves according to Prof. Yohanes Surya, Ph. in the title of the book Vibrations and Waves (2019), propagating vibrations produce energy and move at a certain speed, and do not drag the material they pass through. The use of optical waves is widely applied in medical science, including X-rays as a detector for internal body elements to clarify broken parts such as bones or other things. From the explanation above, it can be concluded that waves are the basis in the world of health, which are of course used in optical equipment, and are a reference for the health team and as a basic concept in physics learning. This underlies the fact that optical waves are not only used in the world of education but are very It is also needed in the world of health.

Shadow and weak gravitational lensing for Ellis-Bronnikov wormhole* *This work is partly Supported by Grants F-FA-2021-432, F-FA-2021-510, and MRB-2021-527 of the Ministry of Higher Education, Science and Innovations of the Republic of Uzbekistan

In this study, we investigated the gravitational weak lensing and shadow of the Ellis-Bronnikov wormhole. First, we studied the photon motion in a plasma medium and a wormhole shadow. It was shown that the radius of the photon sphere of the Ellis-Bronnikov wormhole and the size of the wormhole shadow become larger under the influence of the parameter a. The upper limit of the parameter a in the Ellis-Bronnikov wormhole spacetime was obtained. Second, we investigated the weak gravitational lensing for the Ellis-Bronnikov wormhole and calculated the deflection angle for uniform and non uniform plasma cases. The value of the deflection angle for uniform plasma increased with the increase in plasma parameter value, and vice versa for non uniform plasma. We found that, under the influence of the parameter a, the values of the deflection angles for two cases decreased. Finally, we investigated the magnification of image brightness using the deflection angle of the light rays around the wormhole in the Ellis-Bronnikov theory.

Determination of the value for the bending angle of the light deflection and the impact parameter in Einstein’s theory

The gravitational deflection of the ray of light is one of the famous demonstrations that space-time is curved in the General Theory of Relativity predicted by A Einstein, and later demonstrated by different astronomical experimental observations in solar eclipses. In this work, the deflection of light and the impact parameter in the gravitational field of the Sun are calculated through the solutions to the geodesic equations by the methods of the elliptic functions of Jacobi and Weierstrass, around a central gravitational mass, using the solution found by Schwarzschild to the equations of the gravitational field in the General Theory of Relativity. The results obtained were subjected to a comparative study of the deflection of the light ray experimentally. From this analysis, it is demonstrated that the theoretical results obtained by the Weierstrass and Jacobi methods are in the range of the experimental results calculated during the eclipses of the years 1919 to 1973, demonstrating once again the validity of the General Theory of Relativity that all gravitational mass curves space-time.

Fermat Principle, Ramsey Theory and Metamaterials.

Reinterpretation of the Fermat principle governing the propagation of light in media within the Ramsey theory is suggested. Complete bi-colored graphs corresponding to light propagation in media are considered. The vertices of the graphs correspond to the points in real physical space in which the light sources or sensors are placed. Red links in the graphs correspond to the actual optical paths, emerging from the Fermat principle. A variety of optical events, such as refraction and reflection, may be involved in light propagation. Green links, in turn, denote the trial/virtual optical paths, which actually do not occur. The Ramsey theorem states that within the graph containing six points, inevitably, the actual or virtual optical cycle will be present. The implementation of the Ramsey theorem with regard to light propagation in metamaterials is discussed. The Fermat principle states that in metamaterials, a light ray, in going from point S to point P, must traverse an optical path length L that is stationary with respect to variations of this path. Thus, bi-colored graphs consisting of links corresponding to maxima or minima of the optical paths become possible. The graphs, comprising six vertices, will inevitably demonstrate optical cycles consisting of the mono-colored links corresponding to the maxima or minima of the optical path. The notion of the "inverse graph" is introduced and discussed. The total number of triangles in the "direct" (source) and "inverse" Ramsey optical graphs is the same. The applications of "Ramsey optics" are discussed, and an optical interpretation of the infinite Ramsey theorem is suggested.

“A ray of light in the chaos”: Relationships between companion animals and LGBTQ+ emerging adults during the COVID-19 pandemic

Abstract There is evidence that pet owners experienced benefits during the COVID-19 pandemic and also struggled with pet-related stressors. Notably, almost all of these studies were conducted with predominantly cisgender and heterosexual samples. This is problematic, as evidence suggests that individuals who belong to marginalized groups, such as LGBTQ+ emerging adults, have been disproportionately affected by stressors associated with the pandemic. This qualitative study explores the unique experiences of LGBTQ+ emerging adults who lived with a pet during the COVID-19 pandemic. Additionally, we sought to identify resources needed to assist LGBTQ+ emerging adult pet owners during the pandemic. The sample included 65 participants aged 18–21 years who had lived with one or more pets within the past year (Mean age = 19.5 years; 36.9% transgender/gender diverse; 40% minoritized racial/ethnic identity). We conducted semi-structured interviews consisting of 18 questions (including five COVID-specific questions). Two authors coded and analyzed the interviews using template analysis. Then, the authors used a thematic analysis approach to organize codes into themes, identify patterns of meaning, and examine relations between themes. Four themes emerged related to the experience of living with a pet during the pandemic. Almost all participants said that their pets provided various types of support to them. Many participants stated that their pets also added stress to their lives during the pandemic. Some participants attributed the changes in their pet’s behavior and/or attitude to pandemic-related quarantines. More than half of the participants discussed changes in their relationship with their pet, with the majority claiming their relationship became stronger. Two themes emerged that related to necessary resources: greater community-based resources (e.g., low-cost veterinary care, pet-friendly outdoor spaces) and more government resources (e.g., better access to information, more material and financial support). Participants offered suggestions for ways to alleviate pet-related stressors, such as developing community-based programs (e.g., pet food pantries, mutual aid programs). There is the opportunity for collaboration between researchers and practitioners in piloting these community programs, as well as implications for policy makers to advocate for policies supportive of LGBTQ+ emerging adult pet owners (e.g., university pet policies, housing policies).

Peripheral visual field shifts after intraocular lens implantation.

To assess whether intraocular lens (IOL) implantation induces shifts in the peripheral visual field. Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands. Ray tracing study. Non-sequential ray tracing simulations were performed with phakic and pseudophakic versions of the same eye model to assess potential shifts in the visual field after IOL implantation. Two different IOL designs were evaluated and for each design 5 different axial positions and 7 different intrinsic powers were tested. The relation between the physical position of the light source and the location where the retina was illuminated was determined for each eye model. Subsequently, these relations were used to calculate whether the visual field shifts in pseudophakic eyes. The pseudophakic visual field shift was below 1 degree for central vision in all evaluated models. For peripheral vision, the light rays in the pseudophakic eyes were refracted to a more central retinal location compared to phakic eyes, resulting in a central shift of the peripheral visual field. The magnitude of the shift depended on the IOL design and its axial position, but could be as high as 5.4 degrees towards central vision. IOL implantation tends to have little effect on the central visual field but can induce an over 5 degrees shift in the peripheral visual field. Such a shift can affect the perception of peripheral visual complaints.

Particle dynamics, black hole shadow and weak gravitational lensing in the f (Q) theory of gravity

We study the particle dynamics around a black hole (BH) in f(Q) gravity. First, we investigate the influence of the parameters of f(Q) gravity on the horizon structure of the BH, photon orbits and the radius of the innermost stable circular orbit (ISCO) of massive particles. We further study the effects of the parameters of f(Q) gravity on the shadow cast by the BH. Moreover, we consider weak gravitational lensing using the general method, where we also explore the deflection angle of light rays around the BH in f(Q) gravity in uniform and nonuniform plasma mediums.

Probing Schwarzschild-like black holes in metric-affine bumblebee gravity with accretion disk, deflection angle, greybody bounds, and neutrino propagation

In this paper, we investigate Schwarzschild-like black holes within the framework of metric-affine bumblebee gravity. We explore the implications of such a gravitational setup on various astrophysical phenomena, including the presence of an accretion disk, the deflection angle of light rays, the establishment of greybody bounds, and the propagation of neutrinos. The metric-affine bumblebee gravity theory offers a unique perspective on gravitational interactions by introducing a vector field that couples to spacetime curvature. We analyze the behavior of accretion disks around Schwarzschild-like black holes in this modified gravity scenario, considering the effects of the bumblebee field on the accretion process. Furthermore, we scrutinize the deflection angle of light rays as they traverse the gravitational field, highlighting potential deviations from standard predictions due to the underlying metric-affine structure. Investigating greybody bounds in this context sheds light on the thermal radiation emitted by black holes and how the modified gravity framework influences this phenomenon. Moreover, we explore neutrino propagation around Schwarzschild-like black holes within metric-affine bumblebee gravity, examining alterations in neutrino trajectories and interactions compared to conventional general relativity. By comprehensively probing these aspects, we aim to unravel the distinctive features and consequences of Schwarzschild-like black holes in the context of metric-affine bumblebee gravity, offering new insights into the nature of gravitational interactions and their observable signatures.

Low-cost measurements of the ‘resonant’ wavelengths reflected by a compact disc under skimming light rays

We demonstrate the construction and utilization of an affordable apparatus using readily available materials to accurately measure in a quantitative manner the wavelengths reflected by a compact disc (CD) under skimming light rays. In fact, only a limited number of wavelengths can be revealed when light rays from a white lamp are directed at a CD (or a DVD) in a manner that specifically selects the rays that graze the surface of the horizontally held disc. We compare the results with the ones obtained with a commercial spectrometer, finding that they are in good agreement among them and with the theoretical predictions.