Procedural modeling is a powerful technique used in computer graphics to create geometric models. Instead of manual geometry definition, models are generated implicitly from a set of rules and parameters. Procedural systems have found widespread use in generating content for games, film, and simulation of natural phenomena. Their strength comes from the ability to automatically generate large amount of varied geometry. One of their drawbacks is lack of control because a small change in input parameters often causes large changes in the generated model. <br>In this work we present three novel procedural systems, investigate different forms of control, namely simulation and optimization, and discuss them in terms of general procedural modeling workflow. First we show modeling of 3D objects with arbitrary topology via erosion and deposition simulation controlled by Smoothed Particle Hydrodynamics. Next, we present an algorithm for generating 3D curves using 2D sketches and contextual geometry. Finally, we propose a novel procedural system capable of generating arbitrary type of geometry with respect to user-defined constraints. <br>We show that these systems can be controlled via several means and identify common preconditions that facilitate control: maximizing interactivity and amount of structured information input, minimizing unexpected behaviour, and local control akin to traditional modeling.

Submitted by PPG Ci?ncia da Computa??o (ppgcc@pucrs.br) on 2018-12-13T11:02:57Z No. of bitstreams: 1 Laura Mattos Flach_DIS.pdf: 7411445 bytes, checksum: 79da01d37fd4c16d4a855011a79c3773 (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-12-17T16:10:07Z (GMT) No. of bitstreams: 1 Laura Mattos Flach_DIS.pdf: 7411445 bytes, checksum: 79da01d37fd4c16d4a855011a79c3773 (MD5) / Made available in DSpace on 2018-12-17T16:16:06Z (GMT). No. of bitstreams: 1 Laura Mattos Flach_DIS.pdf: 7411445 bytes, checksum: 79da01d37fd4c16d4a855011a79c3773 (MD5) Previous issue date: 2013-03-15 / This work presents the utilization of procedural modelling to populate environments with virtual agents. It uses previously procedurally generated environments together with a crowd simulator to generate the agents locomotion. This work creates groups based on semantic informations of the environment to be populated and on data retrieved from IBGE for the population of Porto Alegre. It also generates behaviour for each member of the group created. These behaviours are coherent to the environment, to the group?s and member?s characteristics and also to time. All of these characteristics and specifications are transformed into seeds, wich makes the persistence of the data possible (the possibility of the regeneration of the context at any moment without the use of data structures) and the execution more simple (the model is fully automatic). / Este trabalho apresenta a utiliza??o de modelagem procedural para povoar ambientes com agentes virtuais. S?o utilizados ambientes previamente gerados tamb?m de forma procedural, juntamente com um simulador de multid?es para realizar a locomo??o dos agentes. O trabalho, al?m de criar grupos que se baseiam em informa??es sem?nticas do ambiente a ser povoado e em dados retirados do IBGE em rela??o ? popula??o de Porto Alegre, gera comportamentos para cada membro do grupo. Estes comportamentos gerados s?o coerentes com o ambiente, ?s caracter?sticas do grupo e do pr?prio membro, e ao tempo. Todas estas caracter?sticas e especifica??es s?o transformadas em seeds, o que permite a persist?ncia dos dados (possibilita que o contexto seja gerado novamente a qualquer momento sem a utiliza??o de estruturas de dados) e facilita a execu??o (o modelo ? totalmente autom?tico).

The modeling of trees is challenging due to their complex branching structures. Three different ways to generate trees are using real world data for reconstruction, interactive modeling methods and modeling with procedural or rule-based systems. Procedural content generation is the idea of using algorithms to automate content creation processes, and it is useful in plant modeling since it can generate a wide variety of plants that can adapt and react to the environment and changing conditions. This thesis focuses on and extends a procedural tree generation technique that uses a space colonization algorithm to model the tree branches' competition for space, and shifts the previous works' focus from realism to fantasy. The technique satisfied the idea of using interaction between the tree's internal and external factors to determine its final shape, by letting the designer control the where and the how of the tree's growth process. The implementation resulted in a tree generation application where the user's imagination decides the limit of what can be produced, and if that limit is reached can the application be used to randomly generate a wide variety of trees and tree-like structures. A motivation for many researchers in the procedural content generation area is how it can be used to augment human imagination. The result of this thesis can be used for that, by stepping away from the restrictions of realism, and with ease let the user generate widely diverse trees, that are not necessarily realistic but, in most cases, adapts to the idea of a tree.

La génération de mondes virtuels est un domaine de recherche très actif en informatique graphique : la modélisation de plantes, d’arbres, de bâtiments, de villes ou de terrains, et les simulations de vieillissement sont des domaines très explorés. Dans ce contexte, les changements d’apparences constituent également un domaine de recherche important, de part leur impact majeur dans le réalisme des scènes virtuelles produites. Ces travaux se concentrent sur la mise au point d’approches procédurales permettant de représenter les changements d’apparence sous la forme de décorations géométriques (accumulation de neige ou formation de glace, dépôt de feuilles mortes, etc.) à la fois à grande échelle et avec un très haut niveau de détail. Nous proposons d’abord un modèle d’organisation hiérarchique de scènes qui repose sur un arbre de construction dont les feuilles sont des objets environnementaux, des objets qui génèrent eux mêmes leurs décorations géométriques. Nous présentons ensuite un formalisme implicite pour définir l’environnement, qui contient l’ensemble des informations guidant la génération des décorations. Finalement, nous détaillons quatre méthodes de génération procédurale pour la création des décorations géométriques (neige, glace, herbes, feuilles) des objets environnementaux. / Procedural modeling of virtual worlds is an active research field in computer science. A large amount of methods have been published in this field : modeling of plants, trees, buildings, cities or terrains, and aging and weathering simulations. In this context, changes of appearance are a very active research field too, due to the way they impact the realism of produced virtual scenes. This research focuses on a procedural method that can represent the changes of appearance as geometrical decorations (snowfall, ice growth, leaves deposits, etc.) on very big scenes with a high level of details. We first propose a hierarchical scene design based on a construction tree whose leaves are environmental objects, a new kind of objects that generate their own geometrical decorations. We then present an implicit formalism to define the environment that contains all the information needed to guide decorations generation. Finally, we detail four procedural methods for generating the geometrical decorations (snow, ice, grass, leaves) of the environmental objects.

<p>Urban models are of growing importance today for urban and environmental planning, geographic information systems, urban simulations, and as content for entertainment applications. Various methods have addressed aerial or ground scale image-based and sensor-based reconstruction. However, few, if any, approaches have automatically produced urban models from satellite images due to difficulties of data noise, data sparsity, and data uncertainty. Our key observations are that many structures in urban areas exhibit regular properties, and a second or more satellite views for urban structures are usually available. Hence, we can overcome the aforementioned issues obtained from satellite imagery by synthesizing the underlying structure layout. In addition, recent advances in deep learning allow the development of novel algorithms that was not possible several years ago. We leverage relevant deep learning techniques for classifying/predicting urban structure parameters and modeling urban areas that address the problem of satellite data quality and uncertainty. In this dissertation, we present a machine learning-based procedural generation framework to automatically and quickly reconstruct urban areas by using regularities of urban structures (e.g., cities, buildings, facades, roofs, etc.) from satellite imagery, which can be applied to not only multiple resolutions ranging from low resolution (e.g., 3 meters) to high resolutions (e.g., WV3 0.3 meter) of satellite images but also the different scales (e.g., cities, blocks, parcels, buildings, facades) of urban environments. Our method is fully automatic and generates procedural structures in urban areas given satellite imagery. Experimental results show that our method outperforms previous state-of-the-art methods quantitatively and qualitatively for multiple datasets. Furthermore, by applying our framework to multiple urban structures, we demonstrate our approach can be generalized to various pattern types. We also have preliminary results applying this for flooding, archaeological sites, and more.</p>

This thesis details the results and conclusions of a project conducted at the game studio FromSoftware in Tokyo, Japan during the autumn of 2008. The aim ofthe project was the design and implementation of a system able to generate 3D graphical representations of road networks.

Manual modeling of building facades can be a cumbersome process. Instead, procedurally modeling building facades is a practical and quick way to achieve impressive visual results. This paper presents a method for prototyping 2D facades existing in a 3d environment, with the inclusion of shading-based procedural wear-and-tear. State of the art procedural modeling techniques, despite achieving impressive results in general, are lacking in certain specific areas. Urban planners may wish to model the effects of wear-and-tear along with geometric assets and materials on a facade, to prototype future appearances. As of now, a syncretism between a grammar-based procedural modeling system and a procedural wear-and-tear system is relatively unexplored. Exploring how wear-and-tear can replicate damage found on real buildings, and limitations of the used approach, is the primary goal of this research. Furthermore, this work investigates how wear-and-tear can be incorporated into a procedural building facade generation pipeline. Introducing new wear-and-tear functionality to established systems is done by expanding on grammar-like structures to define building shapes, and adding new actions to produce wear-and-tear, which is done by creating textures representing positions of structural components of the facade, and altered and mixed with noise to create damaging effects. The result is a user interface that can combine procedural building modeling with procedural wear-andtear. It can replicate many types of wear-and-tear, such as rust and cracks, although damage such as stains without visible sources or flow-shaped damage is inadequate. The facades accompanying the wear-and-tear are also able to be produced, but is limited in terms of 3D geometric expressibility due to a focus on flat, 2D facades and a deficiency in future flexibility since wear-and-tear cannot be selected in future actions. / Manuell modellering av fasader kan vara en besvärlig process. Istället är procedurell modellering av fasader ett praktiskt och snabbt sätt att uppnå imponerande visuella resultat. I den här rapporten presenteras en metod för prototypering av 2D-fasader som existerar i en 3D-miljö, med inkludering av skuggningsbaserat procedurellt slitage. Den senaste tekniken för procedurell modellering ger generellt sett imponerande resultat, men brister inom vissa specifika områden. Stadsplanerare kan vilja modellera effekterna av slitage tillsammans med geometriska objekt och material på en fasad för att skapa prototyper av framtida utseende. Hittills är synkretismen mellan ett grammatikbaserat procedurmodelleringssystem och ett procedurbaserat slitagesystem relativt outforskat. Det primära målet med denna forskning är att undersöka hur slitage kan replikera skador som finns på verkliga byggnader och begränsningar av det använda tillvägagångssättet. Dessutom undersöks hur slitage kan integreras i en procedurell pipeline för fasadgenerering av byggnader. Införandet av ny funktionalitet för slitage i etablerade system genomförs genom att utöka grammatikliknande strukturer för att definiera byggnadsformer och lägga till nya åtgärder för att åstadkomma slitage, vilket sker genom att skapa texturer som representerar positioner för strukturella komponenter i fasaden, och som förändras och blandas med brus för att skapa skadeeffekter. Resultatet är ett användargränssnitt som kan kombinera procedurell byggnadsmodellering med procedurell slitage. Det kan replikera flera typer av slitage, t.ex. rost och sprickor, dock är skapandet av skador som fläckar utan synliga källor eller flödesformade skador otillräckligt. De fasader som ackompanjerar slitaget kan också framställas procedurellt med detta verktyg, men är begränsade när det gäller uttryck i 3 dimensioner på grund av fokus på platta 2D-fasader och bristande framtida flexibilitet eftersom producerat slitage inte kan utnyttjas i framtida vidare slitageeffekter.

L'objectif principal de cette thèse est de développer des outils pour la reconstruction de l'environnement urbain à partir d'images. Les entrées typiques de notre travail est un ensemble d'images de façades, des empreintes au sol de bâtiments, et des modèles 3D reconstruits à partir d'images aériennes. Les principales étapes comprennent le calibrage des images,le recalage avec le modèle 3D, la récupération des informations de profondeur ainsi que la sémantique des façades.Pour atteindre cet objectif, nous utilisons des techniques du domaine de vision par ordinateur, reconnaissance de formes et de l'informatique graphique. Les contributions de notre approche sont présentés en deux parties.Dans la première partie, nous nous sommes concentrés sur des techniques de reconstruction multi-vues dans le but de récupérer automatiquement les informations de profondeur de façades à partir un ensemble des photographies non calibrées. Tout d'abord, nous utilisons la technique structure et mouvement pour calibrer automatiquement l'ensemble des photographies. Ensuite, nous proposons des techniques pour le recalage de la reconstruction avec un modèle 3D. Enfin, nous proposons des techniques de reconstruction 3d dense (stéréo multi-vues et voxel coloring) pour produire un maillage 3D texturé d'une scène d'un ensemble d'images calibrées.La deuxième partie est consacrée à la reconstruction à partir d'une seule vue et son objectif est de récupérer la structure sémantique d'une façade d'une image ortho-rectifiée. La nouveauté de cette approche est l'utilisation d'une grammaire stochastique décrivant un style architectural comme modèle pour la reconstruction de façades. nous combinons un ensemble de détecteurs image avec une méthode d'optimisation globale stochastique en utilisant l'algorithme Metropolis-Hastings. / The main goal of this thesis is to develop innovative and practicaltools for the reconstruction of buildings from images. The typical input to our workis a set of facade images, building footprints, and coarse 3d models reconstructedfrom aerial images. The main steps include the calibration of the photographs,the registration with the coarse 3d model, the recovery of depth and sematicinformation, and the refinement of the coarse 3d model.To achieve this goal, we use computer vision, pattern recognition and computergraphics techniques. Contributions in this approach are presented on two parts.In the first part, we focused on multiple view reconstruction techniques withthe aim to automatically recover the depth information of facades from a setof uncalibrated photographs. First, we use structure from motion techniques toautomatically calibrate the set of photographs. Then, we propose techniques for theregistration of the sparse reconstruction to a coarse 3d model. Finally, we proposean accelerated multi-view stereo and voxel coloring framework using graphicshardware to produce a textured 3d mesh of a scene from a set of calibrated images.The second part is dedicated to single view reconstruction and its aim is to recoverthe semantic structure of a facade from an ortho-rectified image. The novelty ofthis approach is the use of a stochastic grammar describing an architectural style asa model for facade reconstruction. we combine bottom-up detection with top-downproposals to optimize the facade structure using the Metropolis-Hastings algorithm.

A procedural generation of landscapes often meets a need for real spatial data at finer resolution that data available at the moment. We introduce a method that refines the spatial data at the coarse resolution into the finer resolution utilizing other data sources which are already at the better resolution. We construct weighted local linear statistical models from both the coarse and utility data and use the by- models-learned dependencies between the data sources to predict the needed data at better resolution. To achieve higher computational speed and evade utility data imperfection, we utilize truncated singular value decomposition which reduce a dimensionality of the data space we work with. The~method is highly modifiable and its application shows plausible real-like results. Thanks to this, the method can be of practical use for simulation software development. Powered by TCPDF (www.tcpdf.org)

Afin de créer des productions toujours plus réalistes, les industries du jeu vidéo et du cinéma cherchent à générer des environnements de plus en plus larges et complexes. Cependant, la modélisation manuelle des objets 3D dans de tels décors se révèle très coûteuse. A l’inverse, les méthodes de génération procédurale permettent de créer facilement une grande variété d’objets, tels que les plantes et les bâtiments. La modélisation par règles de grammaire offre un outil de haut niveau pour décrire ces objets, mais utiliser correctement ces règles s’avère très souvent compliqué. De plus, aucune solution de modélisation basée grammaire ne supporte l’édition et la visualisation d’environnements massifs en temps interactif. Dans un tel scénario, les artistes doivent modifier les objets en dehors de la scène avant de voir le résultat intégré.Dans ces travaux de recherche, nous nous intéressons à la génération procédurale et au rendu d’environnements à grande échelle. Nous voulons aussi faciliter la tâche des artistes avec des outils intuitifs de contrôle de grammaires. Tout d’abord nous proposons un système permettant la génération procédurale en parallèle sur le GPU en temps interactif. Pour cela, nous adoptons une approche d’expansion indépendante par segment, permettant une amplification des données en parallèle. Nous étendons ce système pour générer des modèles basés sur une structure interne, tels que les toits. Nous présentons aussi une solution utilisant des contextes externes pour contrôler facilement les grammaires par le biais de surface ou de texture. Pour finir nous intégrons un système de niveaux de détails et des techniques d’optimisation permettant la génération, l’édition et la visualisation interactives d’environnements à grande échelle. Grâce à notre système il est possible de générer et d’afficher interactivement des scènes comprenant des milliers de bâtiments et d’arbres, représentant environ 2 téraoctets de données. / With the increasing computing and storage capabilities of recent hardware, movie and video games industries desire huger realistic environments. However, modeling such sceneries by hand turns out to be highly time consuming and costly. On the other hand, procedural modeling provides methods to easily generate high diversity of elements such as vegetation and architecture. While grammar rules bring a high-level powerful modeling tool, using these rules is often a tedious task, necessitating frustrating trial and error process. Moreover, as no solution proposes real-time generation and rendering for massive environments, artists have to work on separate parts before integrating the whole and see the results.In this research, we aim to provide interactive generation and rendering of very large sceneries, while offering artist-friendly methods for controlling grammars behavior. We first introduce a GPU-based pipeline providing parallel procedural generation at render time. To this end we propose a segment-based expansion method working on independent elements, thus allowing for parallel amplification. We then extend this pipeline to permit the construction of models relying on internal contexts, such as roofs. We also present external contexts to control grammars with surface and texture data. Finally, we integrate a LOD system with optimization techniques within our pipeline providing interactive generation, edition and visualization of massive environments. We demonstrate the efficiency of our pipeline with a scene comprising hundred thousand trees and buildings each, representing 2 terabytes of data.