The Rusterizer: An Art-Directable and Semi-Procedural Tool for Generating Rust Surfaces

The Rusterizer is an art-directable tool designed to facilitate the creation of rust on the surfaces of 3d models. Cellular automata are combined with a procedural shader to create an animated growth effect. A workflow for using the tool is provided. The result is demonstrated with a time-lapse animation of a robot in an alley as it rusts. Future extensions and improvements to the tool are suggested

Fluid computational model for mineral and vegetal pigments diffusing in Chinese color-ink painting

In this paper, simulation of artistic vegetable and mineral pigments diffusing effects of Chinese color-ink painting is presented, using a novel physical model according to the Second Fick's diffusing law and Brownian motion theory. Due to the fact that generation of most art effects depends on complicated pigment-water motion simulation such as diffusing and pigment mixing on and under traditional fabric cotton paper (Xuan paper) surface, the proposed model is found effective for simulating the pigment-water motion in art creating process. Implemented on the GPU, the simulation operations in our system can be accomplished in a real-time manner. The effectiveness of the proposed techniques is validated in our developed Digital Painting System, where various art effects can be successfully re-produced including the Initial area-Darkened initial edge-Diffusion area Lightened diffusion edge (IDDL) effect for vegetable pigments, the Initial area-Darkened initial edge-Diffusion area-Darkened diffusion edge (IDDD) effect for mineral pigments, and multistroke superimposing effects and achieves. In addition, quantitative evaluation is also introduced and shows superior performance of the proposed model in comparison with state-of-the-art techniques

A viscous paint model for interactive applications

We present a viscous paint model for use in an interactive painting system based on the well-known Stokes’ equations for viscous flow. Our method is, to our knowledge, the first unconditionally stable numerical method that treats viscous fluid with a free surface boundary. We have also developed a real-time implementation of the Kubelka-Munk reflectance model for pigment mixing, compositing and rendering entirely on graphics hardware, using programmable fragment shading capabilities. We have integrated our paint model with a prototype painting system, which demonstrates the model’s effectiveness in rendering viscous paint and capturing a thick, impasto-like style of painting. Several users have tested our prototype system and were able to start creating original art work in an intuitive manner not possible with the existing techniques in commercial systems

Particle staining: physically based texture generation

Computers are being employed in a variety of ways by a variety of individuals to create imagery. Much work has been done to accurately model natural phenomena in the context of computer graphics as well as model specific artists' tools and techniques. Focusing on the dynamics of water flow across surfaces, it is the goal of this work to develop a physically inspired texturing tool that allows artists to create interesting staining and wearing effects on surfaces. Weathering or the wearing down of materials by natural forces can create complex and beautiful patterns on a variety of surfaces. In this process lies the very essence of the creative act. To distill the essence of the elements of the water staining process, we employ a computer generated particle system in a phenomenological model. The motion of these particles is controlled by physically based constraints, such as wind, gravity, mass, etc. The way in which each particle interacts with or modifies the look of the surface is further controlled by parameters such as surface roughness, surface color and surface hardness. Each particle can remove or deposit material as it flows across the surface, creating complex patterns

Computer graphics simulation of natural mummification by desiccation

© 2020 The Authors. Computer Animation and Virtual Worlds published by John Wiley & Sons, Ltd. Organic bodies are subject to internal processes after death, causing significant structural, and optical changes. Mummification by desiccation leads to volume shrinkage, skin wrinkling, and discoloration. We propose a method to simulate the process of mummification by desiccation and its effects on the corpse's morphology and appearance. The mummifying body is represented by a layered model consisting of a tetrahedral mesh, representing the volume, plus a high resolution triangle surface mesh representing the skin. The finite element method is used to solve the moisture diffusion and the resulting volume deformations. Skin wrinkling is achieved using position based dynamics. In order to model a visually believable reproduction of the skin coloration changes due to mummification, a skin shading approach is used that considers moisture content, hemoglobin content, and oxygen saturation. The main focus of the work in this article is to recreate the appearance changes of mummification by desiccation, which, to the best of our knowledge, has not been attempted before in computer graphics to this level of realism. The suggested approach is able to model changes in the internal structure and the surface appearance of the body which resemble the postmortem processes of natural mummification by desiccation

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

Realistic Aging of Materials in Computer Graphics

One of the most challenging tasks in Computer Graphics (CG) is depicting the accurate appearance of aging and weathered materials. This thesis examines the physical aging process of materials and translates that information into data that can be applied to CG materials resulting in a new prototype system for simulating realistic aging and weathering of CG materials. This new system will enable artists to quickly and accurately generate materials with a realistic appearance of aging and weathering. The resulting user interface generated from this system allows artists to create a variety of realistic and customized layered materials which offers a wide array of complexities. This prototype was then implemented into a studio setting which helped speed up the production process for material generation