Procedural aging techniques of synthetic cities and 3D scenarios

Today we live in an increasingly computerized and demanding world. A world where is constantly presented the need for, the industry of video games and movies, to find ways to create more realistic graphics environments, faster and longer with a huge level of variety. To address this need, the techniques for procedural generation appeared. These techniques were used by the computer graphics industry to create textures to simulate special effects and generate complex natural models, including mostly vegetation. Within these first techniques we can find a wide range of techniques. Subsequently, with the needs to create increasingly more complex and realistic environments, emerged the solution to adapt these algorithms, already known, to something more complex such as the generation of a road infrastructure, the generation of buildings or allowed to practically generate a world only with procedural generation and a set of rules. Although this development is increasingly felt, we noticed there is an interest in a new area, which is the procedural aging of buildings in these graphical worlds. Several authors had proposed to create new and better algorithms of procedural aging in building. These authors when approaching this subject, tend to follow a very unique and specific way, creating an algorithm capable of playing a unique phenomenon of aging. Thus, identified this gap in the literature, it was decided to seize this opportunity and present and develop a procedural aging algorithm applied to buildings that is capable of reproduce different aging phenomena, and that consumes low computational resources being capable of be applied to a huge 3D scenario.Hoje em dia vivemos num mundo cada vez mais computorizado e exigente. Um mundo onde cada vez mais está presente a necessidade de a industria dos jogos de vídeo e dos filmes arranjar maneiras de criar ambientes gráficos mais realistas, mais rapidamente e já com um nível de variedade grande. Para colmatar esta necessidade surgiu então as técnicas de geração procedural. Estas técnicas aliaram-se á industria de computação gráfica para criar texturas naturais, simular efeitos especiais e gerar modelos naturais complexos, incluindo maioritariamente vegetação. Dentro destas primeiras técnicas podemos encontrar as fractais, L-system e Perlin Noise, entre outros. Posteriormente, com a necessidades de criar cada vez mais ambientes mais complexos, surgiu a solução de adaptar estes algoritmos já conhecidos para algo mais complexo, como a geração de uma estrutura rodoviária, ou como a geração de edifícios podendo assim praticamente gerar um mundo inteiro somente com a geração procedural e um conjunto de regras. Apesar de esta evolução ser cada vez mais sentida, notou-se um crescente interesse num tema em partcular, sendo essa, o envelhecimento procedural dos edifícios nestes mundos gráficos. Vários autores até então tinham-se proposto a criar novos e cada vez melhores algoritmos de envelhecimento procedural dos edifícios. Estes autores ao abordar este tema, tendem em seguir um caminho muito singular e especifico, criando um algoritmo capaz de reproduzir um unico fenomeno de envelhecimento. Assim, identificada esta lacuna na literatura, decidiu-se agarrar esta oportunidade e apresentar e desenvolver um algoritmo de envelhecimento procedural aplicado aos edifícios que é capaz de reproduzir diferentes fenomenos de envelhecimento, e que consome poucos recursos computacionais sendo capaz de ser aplicado a um grande cenário 3D

Simulation of 3D Model, Shape, and Appearance Aging by Physical, Chemical, Biological, Environmental, and Weathering Effects

Physical, chemical, biological, environmental, and weathering effects produce a range of 3D model, shape, and appearance changes. Time introduces an assortment of aging, weathering, and decay processes such as dust, mold, patina, and fractures. These time-varying imperfections provide the viewer with important visual cues for realism and age. Existing approaches that create realistic aging effects still require an excessive amount of time and effort by extremely skilled artists to tediously hand fashion blemishes or simulate simple procedural rules. Most techniques do not scale well to large virtual environments. These limitations have prevented widespread utilization of many aging and weathering algorithms. We introduce a novel method for geometrically and visually simulating these processes in order to create visually realistic scenes. This work proposes the ``mu-ton system, a framework for scattering numerous mu-ton particles throughout an environment to mutate and age the world. We take a point based representation to discretize both the decay effects and the underlying geometry. The mu-ton particles simulate interactions between multiple phenomena. This mutation process changes both the physical properties of the external surface layer and the internal volume substrate. The mutation may add or subtract imperfections into the environment as objects age. First we review related work in aging and weathering, and illustrate the limitations of the current data-driven and physically based approaches. We provide a taxonomy of aging processes. We then describe the structure for our ``mu-ton framework, and we provide the user a short tutorial how to setup different effects. The first application of the ``mu-ton system focuses on inorganic aging and decay. We demonstrate changing material properties on a variety of objects, and simulate their transformation. We show the application of our system aging a simple city alley on different materials. The second application of the ``mu-ton system focuses organic aging. We provide details on simulating a variety of growth processes. We then evaluate and analyze the ``mu-ton framework and compare our results with ``gamma-ton tracing. Finally, we outline the contributions this thesis provides to computer-based aging and weathering simulation

On Improving Urban Environment Representations

Computer Graphics has evolved into a mature and powerful field that offers many opportunities to enhance different disciplines, adapting to the specific needs of each. One of these important fields is the design and analysis of Urban Environments. In this article we try to offer a perspective of one of the sectors identified in Urban Environment studies: Urbanization. More precisely we focus on geometric and appearance modeling, rendering and simulation tools to help stakeholders in key decision stages of the process

Environmental Objects for Authoring Procedural Scenes

International audienceWe propose a novel approach for authoring large scenes with automatic enhancement of objects to create geometric decoration details such as snow cover, icicles, fallen leaves, grass tufts or even trash. We introduce environmental objects that extend an input object geometry with a set of procedural effects that defines how the object reacts to the environment, and by a set of scalar fields that defines the influence of the object over of the environment. The user controls the scene by modifying environmental variables, such as temperature or humidity fields. The scene definition is hierarchical: objects can be grouped and their behaviours can be set at each level of the hierarchy. Our per object definition allows us to optimize and accelerate the effects computation, which also enables us to generate large scenes with many geometric details at a very high level of detail. In our implementation, a complex urban scene of 10 000 m², represented with details of less than 1 cm, can be locally modified and entirely regenerated in a few seconds

Usage Based Materials by Simulating Layered Imperfections

Maintaining the ability to make quick iterations is very important to any artist in Computer Graphics, which is not always easy for simulating realistic materials based on how they are used. This thesis will examine imperfections in materials and the way different imperfections interact with each other based on how they are used. A new system will be created to save artist time by simulating how imperfections are layered and positioned

PHOTOGRAMMETRY DRIVEN TOOLS TO SUPPORT THE RESTORATION OF OPEN-AIR BRONZE SURFACES OF SCULPTURES: AN INTEGRATED SOLUTION STARTING FROM THE EXPERIENCE OF THE NEPTUNE FOUNTAIN IN BOLOGNA

Checking the irreversible process of clean-up is a delicate task that requires a work of synthesis between theoretical knowledge and practical experience, to define an effective operating protocol on a limited patch area to be extended later to the entire artefact's surface. In this paper, we present a new, quick, semi-automated 3D photogrammetry-based solution to support restorers in the open-air bronze artwork cleaning from corrosion and weathering decay. The solution allows the conservators to assess in real time and with a high level of fidelity in colour and shape, the 'surfaces' to be cleaned before, during and after the clear-out treatment. The solution besides allows an effective and valuable support tool for restorers to identify the original layer of the bronze surface, developed and validated during the ongoing restoration of the Neptune Fountain in Bologna

Data-Driven Scratch Generation for Rigid-Body Models

The procedural scratch generation process for rigid-body models automates the process of locating and painting scratches on a texture map. A script computes points where a scratch is most likely to occur at each frame of an animation sequence based on whether the distance between two objects lies within a threshold. These points are then used to create a map of the scratch pattern to guide the blending of scratches onto the image. The tool may be useful to expedite the animated film production pipeline as well as predict areas of wear on machines before they are manufactured

Example-Based Fractured Appearance

International audienceA common weathering effect is the appearance of cracks due to material fractures. Previous exemplar-based aging and weathering methods have either reused images or sought to replicate observed patterns exactly. We introduce a new approach to exemplar-based modeling that creates weathered patterns on synthetic objects by matching the statistics of fracture patterns in a photograph. We present a user study to determine which statistics are correlated to visual similarity and how they are perceived by the user. We then describe a revised physically-based fracture model capable of producing a wide range of crack patterns at interactive rates. We demonstrate how a Bayesian optimization method can determine the parameters of this model so it can produce a pattern with the same key statistics as an exemplar. Finally, we present results using our approach and various exemplars to produce a variety of fracture effects in synthetic renderings of complex environments. The speed of the fracture simulation allows interactive previews of the fractured results and its application on large scale environments

DAA: A Delta Age AdaIN operation for age estimation via binary code transformer

Naked eye recognition of age is usually based on comparison with the age of others. However, this idea is ignored by computer tasks because it is difficult to obtain representative contrast images of each age. Inspired by the transfer learning, we designed the Delta Age AdaIN (DAA) operation to obtain the feature difference with each age, which obtains the style map of each age through the learned values representing the mean and standard deviation. We let the input of transfer learning as the binary code of age natural number to obtain continuous age feature information. The learned two groups of values in Binary code mapping are corresponding to the mean and standard deviation of the comparison ages. In summary, our method consists of four parts: FaceEncoder, DAA operation, Binary code mapping, and AgeDecoder modules. After getting the delta age via AgeDecoder, we take the average value of all comparison ages and delta ages as the predicted age. Compared with state-of-the-art methods, our method achieves better performance with fewer parameters on multiple facial age datasets.Comment: Accepted by CVPR2023; 8 pages, 3 figure