Дисертації з теми "Illumination map"

Context. Indirect illumination – the light contribution from bounce light in an environment – is an important effect when creating realistic images. Historically it has been approximated very poorly by applying a constant ambient term. This approximation is unacceptable if the goal is to create realistic results as bouncing light contributes a lot of light in the real world. Objectives. This thesis proposes a technique to use a reflective shadow map to place and configure spotlights in an environment to approximate global illumination. Methods. The proposed spotlight distribution technique is implemented in a delimited real time graphics engine, and the results are compared to a naive spotlight distribution method. Results. The image resulting from the proposed technique has a lower quality than the comparison in our test scene. Conclusions. The technique could be used in its current state for applications where the view can be controlled by the developer such as in 3D side scrolling games or as a tool to generate editable indirect illumination. Further research needs to be conducted to make it more broadly viable.
Indirekt illuminering är en viktigt effekt om en försöker skapa realistiska bilder. Den här uppsatsen föreslår en teknik där en reflektiv skuggkarta används för att placera och konfigurera strålkastare för att approximera indirekt illuminering. Tekniken kan användas i till exempel sidscrollande 3D spel eller för att skapa ett verktyg som kan användas för att skapa redigerbar indirekt illuminering. Vidare forskning krävs för att göra tekniken rimlig för flera användningsområden.

Dans cette thèse, nous avons présentons une méthode pour orienter automatiquement une carte d'environnement avec une scène locale.Dans la littérature, de nombreuses méthodes ont besoin d'orienter la carte d'environement pour obtenir une cohérence avec une scène locale. Cette orientation est dans la majorité descas effectuée de manière manuelle par un utilisateur. Nous présentons une méthode pour recaler automatiquement un carte d'environement avec une scène locale. Une caractéristique de notre approche est que nous n'avons pas besoin de créer un modèle 3D complet de la scène locale, ni d'interaction avec l'utilisateur. De plus, nous faisons que de simples hypothèses.Nous proposons un pipeline pour créer une représentation virtuelle de la scène en utilisant nos données d'entrée. Cette représentation comprend la scène globale représentée par la carte d'environement et la scène locale représentée par un objet de référence et son ombre.En utilisant la connaissance de la position de la source lumineuse principale sur la carte d'environnement, nous pouvons simuler l'éclairage et projeter une ombre sur le sol. Il est alors possible de comparer la forme de l'ombre calculée avec celle de l'ombre d'entrée pour récupérer la position correcte de la source lumineuse principale. L'orientation finale de la carte d'environement est directement liée à la position de cette source lumineuse principale.Nous fournissons une évaluation de l'approche proposée en calculant deux métriques qui comparent notre estimation d'angle avec les directions réelles au sol. Notre estimation d'orientation montre que notre méthode récupère une orientation de carte d'environement correcte
In this thesis, we have presented a method to register an environment map with a local scene automatically.In the literature, many methods need to orient the environmental map to be coherent with a local scene. This orientation is mostly done manually by a user. We present a method to register an environment map with a local scene automatically. A characteristic of our approach is that we do not need to create a complete 3D model of the local scene or have interaction with the user. Moreover, we are making simple assumptions.We propose a pipeline to create a virtual representation of the scene using our input data. This representation includes the global scene represented by the environment map and the local scene represented by a reference object and its shadow.By using the knowledge of the position of the main light source on the environment map, we can simulate the lighting and project a computed shadow on the ground. It is possible to compare the computed shadow shape with the input one to recover the correct position of the main light source. The final orientation of the environment map is directly related to the position of this main light source.We provide an evaluation of the proposed approach by calculating two metrics that compare our angle estimate with actual ground truth directions. Our orientation estimation shows that our method recovers a correct environment map orientation.In this thesis, we are interested in real input data. The environment map and the local scene are extracted from photographs or videos, which already contain a lighting rendering. It is therefore important to orient the environment map in a way that is consistent with the existing lighting in the local scene.We propose an automatic method, to orient an environment map to a local scene. This method is inspired by the behavior of light, drawing rays of light towards an object and attempting to match two shadows, one given as input and one calculated.We also use 3D data from the object we are considering. The originality is that we base our method on the way light behaves in order to calculate and match shadows. By matching the shadows, we can estimate the correct position of the environment map

Shader programming is important for realistic material and global illumination real-time rendering, especially in 3D industrial fields nowadays, more and more customers of Visual Components Oy, a Finnish 3D software company have been found to be no longer only content with the correct simulation result, but also the result of realistic real-time rendering. This thesis project will provide a deep research on real world material classification, property definition and global illumination techniques in industrial fields. On the other hand, the Shader program for different materials and global illumination techniques are also created according to the classification and definition in this thesis work. Moreover, an external rendering tool Redway3D is evaluated as the reference and regarded as the considerable solution in the future development work.

Global illumination is an important factor when striving for photo realism in computergraphics. This thesis describes why this is the case, and why global illumination is considered acomplex problem to solve. The problem becomes even more demanding when considering realtime purposes. Resent research has proven it possible to produce global illumination in realtime. Therefore the subject of this thesis is to compare and evaluate a number of those methods. An implementation is presented based on the Imperfect shadow maps method, which per se isbased on instant radiosity and reflective shadow maps. The implementation is able to renderplausible global illumination effects in real time, for fully dynamic scenes. With conclusions that while it demonstrably is possible to provide believable global illum-ination in real time, it is not without shortcomings. In every case approximations or restrictionshas to be done to some extent, sometimes leading to wrong results. Though in most cases, notvisually unpleasing by a great deal. The final conclusion is that global illumination is possible on current hardware, with believablequality and good speed. Showing great potential for future implementations on next generationof hardware.

This thesis is focused on describing methods of computation of global illumination of 3D graphics scenes in real-time. First chapter contains brief introduction to the issue of global illumination (GI) computation, as well as quick summarisation of principles of most commonly used GI computation approaches. A method of visibility computing for indirect illumination, taking advantage of Imperfect Shadow Mapping, is introduced next. After closer examination of this method and prerequisite algorithms follows a description of its practical implementation, as well as of the structure of simple demonstrative application. Next chapter then contains testing and brief examination and evaluation of resulting program's behaviour. Finally, a possible method extension by means of virtual point light clustering is proposed.

The growing demand for realistic renderings in both film and games has led to a number of proposed solutions to the Global Illumination problem. In order to imitate natural lighting, it is necessary to gather indirect illumination of the surrounding environment for lighting computations. This is a computationally expensive problem, requiring the sampling or rasterization of the hemisphere surrounding each ray intersection, to which there is no standardized solution. In this thesis we propose a new method of approximation using environment maps for caching radiance. The proposed method leverages a voxelized scene representation for storing direct illumination and a cache of environment maps for integrating indirect illumination. By using a voxelized scene to gather indirect lighting contributions and caching these contributions spatially, we are able to achieve fast and convincing renders of large complex scenes. The result of our implementation produces images comparable to those of existing Monte Carlo integration methods with render speeds a magnitude or more faster.

This thesis deals with practical implementation of photon mapping algorithm. To achieve better results some basic and some more advanced methods of global illumination has been examined. These time demanding algorithms are often practically unusable and their further optimization is necessary. Optimized ray tracer is essential for practical implementation. Computing diffuse interreflection by Monte Carlo sampling is also very time demanding operation. Therefore it is appropriate to use it along with proper interpolation.

This thesis deals with problem of computation of global illumination in real-time. Two methods are described. Namely Reflective Shadow Maps and Light Propagation Volumes. The first of them deals with the problem by using extended Shadow Mapping algorithm. The second one uses scene embedded into a 3D grid together with Spherical harmonics to compute light propagation in the scene. Furthermore this thesis contains results of measurement of the rendering speed of the Light Propagation Volumes algorithm with various settings on several machines. Quality of the resulting output of the algorithm is also evaluated.

Les méthodes stochastiques de Monte-Carlo représentent une solution élégante permettant de calculer des effets d'illumination globale de manière plus réaliste que d'autres algorithmes de rendus. Toutefois, le principal inconvénient de ces méthodes réside dans les temps de calcul conséquents qu'ils immpliquent la plupart du temps. Que ce soit par l'utilisation de structures de données hiérarchiques ou par la distribution des calculs sur un cluster d'ordinateurs personnels en passant par l'implémentation sur une architecture de type super-ordinateur, nombre de méthodes existent en vues d'améliorer les performances des algorithmes de Monte-Carlo en terme de temps de rendu. Nous apportons une contribution à ce domaine très actif en abordant la question sous plusieurs angles. D'une part nous proposons une étude approfondie d'un serveur de calcul commercial dédié au calcul de lancer de rayons, et nous proposons une méthode afin d'étendre le champ d'appliqations de ce serveur aux techniques de Monte-Carlo pour le rendu. D'autre part, nous présentons une méthode de classification des rayons au sein et une reconstruction des algorithmes de Monte-Carlo classiques, permettant ainsi une utilisation efficace des cartes graphiques programmables récentes pour l'accélération du calcul d'intersections intervenants dans le processus. Enfin nous proposons l'architecture logicielle modulable IGLOO, conçue dans le cadre de cette thèse afin de disposer au sein du Laboratoire d'Informatique du Littoral d'une plate-forme de développement et de comparaison des techniques de Monte-Carlo commune servant de base à de nombreux projets en cours dans le cadre d'autres travaux
Monte-Carlo methods are elegant and efficient solutions for computing realistic global illumination effects far better than most other algorithms. However the main drawback of these methods appears in the important rendering times involved by such techniques. By using adapted hierarchical data structures, distributing the main part of computations on a large personal computer cluster or even designing a specific dedicated software for a specific supercomputer architecture, many solutions exist, trying to improve Monte-Carlo algorithms performances from a rendering time point of view. In our work we contribute to this particularly active research topic and we approach it in several and complementary ways. First of all we propose a near complete study of ray-tracing dedicated server, and we propose to extend ots capabilities to the use of Monte-Carlo methods for rendering. Then, we present a specific method of our own in order to classify rays and an adapted rebuild of classical Monte-Carlo algorithms, so we can efficiently use modern programmable graphics cards to accelerate intersections tests involved in the rendering process. Last but not least, we present the IGLOO modular software architecture. It has been designed and implemented during this thesis in order to permit the whole LIL Laboratory to benefit from a commune development and benchmark platform for Monte-Carlo methods. This architecture is at the basis of many other thesis works actually in progress

1. Iconographie à Beaulieu-sur-Dordogne.Le portail de Beaulieu-sur-Dordogne est une œuvre majeure du xiie siècle. Pourtant, jusqu’à présent, les registres inférieurs du tympan étaient décrits de manière insatisfaisante comme une masse de créatures. La première partie de cette thèse est une lecture iconographique du tympan puis de l’ensemble de l’édifice par méthode comparative sérielle.L'Apocalypse est la référence principale du tympan. Les trois créatures du linteau représentent la Bête de la Terre, la Bête de la Mer et le Dragon, tirées de l'Apocalypse 13. Leur manifestation comme anti-trinité est une incarnation du mal. Mais les quatre créatures au niveau intermédiaire sont des locustes, c'est-à-dire un fléau envoyé par Dieu. S’y ajoutent plusieurs micro-motifs, tels que les roses végétales ou les têtes crachant des rubans. Mes interprétations iconographiques fondent une compréhension renouvelée de la composition. Le tympan de Beaulieu offre une perspective sur les événements apocalyptiques centrée sur la notion d’épreuve : les épreuves eschatologiques et les épreuves de la vie, les efforts et tentations y compris celles du Christ, construisent un réseau de motifs analogiques à travers le portail. J’ai nommé ce thème : « adversité apocalyptique ».2. Adversité apocalyptique.À partir du ve siècle, il est admis que l'Apocalypse symbolise le présent. Or le tympan de Beaulieu associe seconde Parousie et bêtes apocalyptiques. C’est que certains passages dans les commentaires apocalyptiques montrent que les théologiens jusqu’au xiie siècle interprètent le texte à la fois comme une clef métaphorique au présent et comme une annonce au futur. Une fois identifiés et déchiffrés, ces motifs d'épreuves apocalyptiques sont repérables en contexte eschatologique dans de nombreux monuments romans et du premier gothique. Certains étaient encore non identifiés, comme la locuste de Schloss Tirol. Quelques compositions monumentales incluant des épreuves apocalyptiques ont été décrites par leurs contemporains mais plus tard détruites, comme à Saint-Benoît-sur-Loire.Au milieu du xiiie siècle, des images apocalyptiques sont réutilisées par des penseurs hétérodoxes, puis par des mouvements subversifs comme celui des Flagellants à partir de 1256, suivis d'un certain nombre de mouvements millénaristes. Dès ce moment, une partie de l’iconographie apocalyptique devient suspecte et disparaît des représentations monumentales pour quelques siècles.3. Analyse anthropologique.La série des images apocalyptiques documente le passage d'une ontologie analogiste à l’ontologie naturaliste contemporaine. Suivant la théorie de l'anthropologue Philippe Descola, la première, issue d'un cadre de discontinuités tant dans les matériaux physiques qu’entre les êtres spirituels, se caractérise par un usage constant de l'analogie afin de réconcilier les réalités fragmentées du cosmos. L'ontologie naturaliste, quant à elle, oppose réalité matérielle continue régie par des lois scientifiques naturelles, et discontinuité dans les mondes culturels et psychologiques des êtres humains et non-humains. Les traits de la figuration analogiste sont pertinents pour comprendre des images romanes dont la valeur est plutôt cosmologique qu’exégétique. Il en va ainsi des séries de figures animales situées autour du portail de Moissac, ou en façade de Notre-Dame La Grande, à Poitiers. Notre corpus peut aussi éclairer la mutation ontologique. Les critères en sont multiples : la structure des images, leur référence thématique, l’usage de motifs comme l’hybridation, la place donnée aux créatures non-humaines, etc. Dès le xiiiᵉ siècle, les formes les plus complexes de la figuration analogiste reculent et un certain nombre d’éléments disparaissent, tels que la prolixité dans l’hybridation. Ces jalons très précoces permettent de mieux saisir la complexité de la trajectoire qui aboutit au naturalisme, à partir du xvᵉ siècle dans les images et de manière systématique dans les textes au xviiᵉ siècle
. Iconography in Beaulieu-sur-Dordogne.The Beaulieu portal is a major landmark of the Twelfth Century. However, the lower levels of the tympanum have so far been described unsatisfactorily as an indistinct mass of evil creatures. The first part of this thesis is an iconographic reading of the tympanum, then of the whole building, by serial comparative method.On the tympanum, the Apocalypse is the main reference. The three creatures in the lintel represent the Beast of the Earth, the Beast of the Sea and the Dragon, taken from Revelation 13. Their ironic manifestation as anti-trinity must be understood as the incarnation of Evil. On the other hand, the four creatures at the intermediate level are locusts, that is a plague, but sent by God. Finally, there are a multitude of micro-motifs, such as vegetal roses or ribbons-spitting heads. Iconographic interpretations are the basis for a renewed understanding of the composition. Beaulieu's tympanum is a thematic perspective on the end times and apocalyptic events, centred on the notion of trial: eschatological trials and the trials of terrestrial life. The efforts and temptations, including the temptation of Christ, build a network of analogical motifs through the portal. I have named this theme: "apocalyptic adversity".2. Apocalyptic adversity. It is commonly accepted that from the 5th century, Revelation is interpreted as a symbolic representation of the present. However, Beaulieu's tympanum associates second Parousia and apocalyptic beasts. In fact, some passages in apocalyptic commentaries show that many theologians until the Twelfth Century interpret the text with fluidity both as a metaphorical key to the present and as a possible eschatological announcement. Once identified and deciphered, the apocalyptic motifs are visible in eschatological contexts in many Romanesque and early Gothic monuments. Some of them were previously unidentified, such as the locust in Schloss Tirol. Some monumental compositions including elements of apocalyptic trials had been described by their contemporaries but later destroyed, as in Saint-Benoît-sur-Loire. In the middle of the Thirteenth Century, apocalyptic images were reused by heterodox thinkers, then by subversive movements such as the Flagellants from 1256, followed by movements often referred to as millenarists. From that moment, much of the apocalyptic iconography became suspicious and disappeared from monumental representations for a few centuries. 3. Anthropological analysis of images. The series of apocalyptic images also documents the transition from analogist ontology to contemporary naturalist ontology. According to the theory of anthropologist Philippe Descola, the first, resulting from discontinuities both in physical materials and between spiritual beings, is characterized by a constant use of analogy, in order to reconcile the fragmented realities of the cosmos. Naturalistic ontology, on the other hand, contrasts a continuous material reality governed by natural scientific laws, with a discontinuity in the cultural and psychological worlds of human and non-human beings. The features of analogist figuration are relevant to many Romanesque images, whose value is more cosmological than exegetical. This is the case for the series of animal figures located around the Moissac gate, or on the façade of Notre-Dame La Grande in Poitiers. Our corpus can also shed light onto the ontological mutation. The criteria are manifold. They concern the structure of the images, their thematic reference, the use of certain motifs such as hybridization, the place given to non-human creatures, etc. From the xiiiᵉ century, the most complex forms of analogist figuration recede. Then a certain number of elements gradually appear, such as hybridization. These early milestones make it possible to better understand the complexity of the trajectory leading to naturalism, starting from xvᵉ century in the images, and systematically in the texts in xviiᵉ century

In this thesis we tackle two problems, namely, the data interpolation prob- lem in the context of depth computation both for images and for videos, and the problem of the estimation of the apparent movement of objects in image sequences. The rst problem deals with completion of depth data in a region of an image or video where data are missing due to occlusions, unreliable data, damage or lost of data during acquisition. In this thesis we tackle it in two ways. First, we propose a non-local gradient-based energy which is able to complete planes locally. We consider this model as an extension of the bilateral lter to the gradient domain. We have successfully evaluated our model to complete synthetic depth images and also incomplete depth maps provided by a Kinect sensor. The second approach to tackle the problem is an experimental study of the Biased Absolutely Minimizing Lipschitz Extension (biased AMLE in short) for anisotropic interpolation of depth data to big empty regions without informa- tion. The AMLE operator is a cone interpolator, but the biased AMLE is an exponential cone interpolator which makes it more addapted to depth maps of real scenes that usually present soft convex or concave surfaces. Moreover, the biased AMLE operator is able to expand depth data to huge regions. By con- sidering the image domain endowed with an anisotropic metric, the proposed method is able to take into account the underlying geometric information in order not to interpolate across the boundary of objects at di erent depths. We have proposed a numerical model to compute the solution of the biased AMLE which is based on the eikonal operators. Additionally, we have extended the proposed numerical model to video sequences. The second problem deals with the motion estimation of the objects in a video sequence. This problem is known as the optical ow computation. The Optical ow problem is one of the most challenging problems in computer vision. Traditional models to estimate it fail in presence of occlusions and non-uniform illumination. To tackle these problems we proposed a variational model to jointly estimate optical ow and occlusion. Moreover, the proposed model is able to deal with the usual drawback of variational methods in dealing with fast displacements of objects in the scene which are larger than the object it- self. The addition of a term that balance gradient and intensities increases the robustness to illumination changes of the proposed model. The inclusions of a supplementary matches given by exhaustive search in speci cs locations helps to follow large displacements.
En esta tesis se abordan dos problemas: interpolación de datos en el contexto del cálculo de disparidades tanto para imágenes como para video, y el problema de la estimación del movimiento aparente de objetos en una secuencia de imágenes. El primer problema trata de la completación de datos de profundidad en una región de la imagen o video dónde los datos se han perdido debido a oclusiones, datos no confiables, datos dañados o pérdida de datos durante la adquisición. En esta tesis estos problemas se abordan de dos maneras. Primero, se propone una energía basada en gradientes no-locales, energía que puede (localmente) completar planos. Se considera este modelo como una extensión del filtro bilateral al dominio del gradiente. Se ha evaluado en forma exitosa el modelo para completar datos sintéticos y también mapas de profundidad incompletos de un sensor Kinect. El segundo enfoque, para abordar el problema, es un estudio experimental del biased AMLE (Biased Absolutely Minimizing Lipschitz Extension) para interpolación anisotrópica de datos de profundidad en grandes regiones sin información. El operador AMLE es un interpolador de conos, pero el operador biased AMLE es un interpolador de conos exponenciales lo que lo hace estar más adaptado a mapas de profundidad de escenas reales (las que comunmente presentan superficies convexas, concavas y suaves). Además, el operador biased AMLE puede expandir datos de profundidad a regiones grandes. Considerando al dominio de la imagen dotado de una métrica anisotrópica, el método propuesto puede tomar en cuenta información geométrica subyacente para no interpolar a través de los límites de los objetos a diferentes profundidades. Se ha propuesto un modelo numérico, basado en el operador eikonal, para calcular la solución del biased AMLE. Adicionalmente, se ha extendido el modelo numérico a sequencias de video. El cálculo del flujo óptico es uno de los problemas más desafiantes para la visión por computador. Los modelos tradicionales fallan al estimar el flujo óptico en presencia de oclusiones o iluminación no uniforme. Para abordar este problema se propone un modelo variacional para conjuntamente estimar flujo óptico y oclusiones. Además, el modelo propuesto puede tolerar, una limitación tradicional de los métodos variacionales, desplazamientos rápidos de objetos que son más grandes que el tamaño objeto en la escena. La adición de un término para el balance de gradientes e intensidades aumenta la robustez del modelo propuesto ante cambios de iluminación. La inclusión de correspondencias adicionales (obtenidas usando búsqueda exhaustiva en ubicaciones específicas) ayuda a estimar grandes desplazamientos.

碩士
國立臺灣大學
資訊工程學研究所
97
We present an algorithm for rendering global illumination while the scene, camera, and light sources can be fully dynamic. We achieve this by generating an occlusion map of each pixel on screen and take the occlusions as indirect light sources to produce the global illumination effects. By exploiting the occlusion map, global illumination effects including soft shadow, reflective lighting, and multi-bounce lighting can be produced by iteratively rendering process. We have approximated the rendering equation and accelerate it to interactive rate.

Lighting design and modelling (the efficient and aesthetic placement of luminaires in a virtual or real scene) or industrial applications like luminaire planning and commissioning (the luminaire's installation and evaluation process along to the scene's geometry and structure) rely heavily on high realism and physically correct simulations. The current typical approaches are based only on CAD modeling simulations and offline rendering, with long processing times and therefore inflexible workflows. In this thesis we examine whether different camera-aided light modeling and numerical optimization approaches could be used to accurately understand, model and measure the light distribution in real life scenarios within real world environments. We show that factorization techniques could play a semantic role for light decomposition and light source identification, while we contribute a novel benchmark dataset and metrics for it. Thereafter we adapt a well known global illumination model (i.e. radiosity) and we extend it so that to overcome some of its basic limitations related to the assumption of point based only light sources or the adaption of only isotropic light perception sensors. We show that this extended radiosity numerical model can challenge the state-of-the-art in obtaining accurate dense spatial light measurements over time and in different scenarios. Finally we combine the latter model with human-centric sensing information and present how this could be beneficial for smart lighting applications related to quality lighting and power efficiency. Thus, with this work we contribute by setting the baselines for using an RGBD camera input as the only requirement to light modeling methods for light estimation in real life scenarios, and open a new applicability where the illumination modeling can be turned into an interactive process, allowing for real-time modifications and immediate feedback on the spatial illumination of a scene over time towards quality lighting and energy efficient solutions.

Thesis (M.S.)--University of Wisconsin--Madison, 1998.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 99-103).

This work introduces a method for optimal combination of light paths generated from the camera and from the light sources in the Photon Mapping algorithm used for computing global illumination. Our method is based on Multiple Importance Sampling, a general approach, introduced by Veach, for adaptive path connection in Bidirectional Path-Tracing. Our goal is to examine this method in connection with the biased algorithm of Photon Mapping and to improve the ineffective heuristic used in the original version of this algorithm. This heuristic is usually problematic when applied to the scenes where highly glossy materials prevail.

Thesis (M.A.)--Indiana University, 2007.
Title from screen (viewed on May 23, 2007) Department of English, Indiana University-Purdue University Indianapolis (IUPUI) Includes vita. Includes bibliographical references (leaves 82-83)