Two algorithms for fast 2D node generation: application to RBF meshless discretization of diffusion problems and image halftoning

Mesh generation techniques for traditional mesh based numerical approaches such as FEM and FVM have now reached a good degree of maturity. There is no such an acknowledged background when dealing with node generation techniques for meshless numerical approaches, despite their theoretical simplicity and efficiency; furthermore node generation can be put in connection with some well-known image approximation techniques. Two node generation algorithms are here proposed and employed in the numerical solution of 2D steady state diffusion problems by means of a local Radial Basis Function (RBF) meshless method. Finally, such algorithms are also tested for greyscale image approximation through stippling

Img2Logo:Generating Golden Ratio Logos from Images

Logos are one of the most important graphic design forms that use an abstracted shape to clearly represent the spirit of a community. Among various styles of abstraction, a particular golden-ratio design is frequently employed by designers to create a concise and regular logo. In this context, designers utilize a set of circular arcs with golden ratios (i.e., all arcs are taken from circles whose radii form a geometric series based on the golden ratio) as the design elements to manually approximate a target shape. This error-prone process requires a large amount of time and effort, posing a significant challenge for design space exploration. In this work, we present a novel computational framework that can automatically generate golden ratio logo abstractions from an input image. Our framework is based on a set of carefully identified design principles and a constrained optimization formulation respecting these principles. We also propose a progressive approach that can efficiently solve the optimization problem, resulting in a sequence of abstractions that approximate the input at decreasing levels of detail. We evaluate our work by testing on images with different formats including real photos, clip arts, and line drawings. We also extensively validate the key components and compare our results with manual results by designers to demonstrate the effectiveness of our framework. Moreover, our framework can largely benefit design space exploration via easy specification of design parameters such as abstraction levels, golden circle sizes, etc

Hyper-Realist Rendering: A Theoretical Framework

This is the first paper in a series on hyper-realist rendering. In this paper, we introduce the concept of hyper-realist rendering and present a theoretical framework to obtain hyper-realist images. We are using the term Hyper-realism as an umbrella word that captures all types of visual artifacts that can evoke an impression of reality. The hyper-realist artifacts are visual representations that are not necessarily created by following logical and physical principles and can still be perceived as representations of reality. This idea stems from the principles of representational arts, which attain visually acceptable renderings of scenes without implementing strict physical laws of optics and materials. The objective of this work is to demonstrate that it is possible to obtain visually acceptable illusions of reality by employing such artistic approaches. With representational art methods, we can even obtain an alternate illusion of reality that looks more real even when it is not real. This paper demonstrates that it is common to create illusions of reality in visual arts with examples of paintings by representational artists. We propose an approach to obtain expressive local and global illuminations to obtain these stylistic illusions with a set of well-defined and formal methods.Comment: 20 page

Stylized 3D Scene Synthesis in Virtual Reality

Many forms of life in the natural world have the extraordinary capacity to sense their environments, to learn, and to remember, just as humans do, even though they are vastly different from us. In this dissertation, I presented novel techniques developed to exhibit an interactive abstract virtual reality experience that invites viewers to see the natural world from a different perspective. I developed the vertex displacement and color turbulence approaches to showcase organisms. The organisms can also modulate their shapes according to the volumes and frequencies of sound. Furthermore, the experience displays turbulent flow on the organisms’ surface to demonstrate the concept of energy flow, or vitality, among all organisms in the natural world. Another novel feature is that viewers can interact with the surface colors through ray casting from a handheld controller

A Survey of Digital Stippling

International audienceIn this article we survey techniques for the digital simulation of handmade stippling—one of the core techniques developed within non-photorealistic/expressive rendering. Over the years, a plethora of automatic or semi-automatic stippling algorithms have been proposed. As part of this expanding field of research, techniques have been developed that not only push the boundaries of traditional stippling but that also relate to other processes or techniques. Our general goal in this survey is thus to increase our understanding of both handmade and computer-assisted stippling. For this purpose we not only provide an overview of the work on digital stippling but also examine its relationship to traditional stippling and to related fields such as halftoning. Finally, we propose several directions of future work in the field