Discrete Texture Design Using a Programmable Approach

International audienceIn this work, we call "discrete texture" any repetitive pattern composed of small, perceivable elements. A lot of art techniques involve manual production of discrete textures, that is very expensive. We address the problem of discrete texture synthesis. Previous works introduced by-example tools: simple interfaces that allow one to draw a small texture exemplar. The tool analyses this exemplar and reproduces it on a larger scale. However, these algorithms fail to reproduce faithfully both large scale effects and local structures of elements. In contrast, our approach allows one to write the program that synthesizes the texture. We provide a set of operators that distribute points, curves or regions in the plane. We show that a large range of textures can be easily designed with our system. Additionaly, we prove that many variants of classic element distribution algorithms can be written as simple combinations of our operators

ColorSketch: A Drawing Assistant for Generating Color Sketches from Photos

postprin

Developing Generalized Cross Hatching Shader Approach for Non-Photorealistic Rendering

In this research, I present a method for rendering a geometric scene that has the look and feel of artistic hand drawings, particularly using a medium such as charcoal or crosshatching. While there have been many approaches to non-photorealistic (NPR) renderings in the past two decades, there seems to be very little research done on how to obtain such charcoal or cross-hatching effects, especially with attention to reflections and specularity, which often at times seems to break the illusion of the drawing effect. I developed a new class of techniques, using a Barycentric shading method, that allows the non-photorealistic rendering of a variety of artistic drawing styles. My approach can be summarized as follows: (1) a Barycentric shader that can provide generalized crosshatching with opaque multi-textures, (2) a Barycentric shader using transparent multitextures, and (3) a texture synthesis method that can automatically produce crosshatching textures from any given image

Developing Generalized Cross Hatching Shader Approach for Non-Photorealistic Rendering

In this research, I present a method for rendering a geometric scene that has the look and feel of artistic hand drawings, particularly using a medium such as charcoal or crosshatching. While there have been many approaches to non-photorealistic (NPR) renderings in the past two decades, there seems to be very little research done on how to obtain such charcoal or cross-hatching effects, especially with attention to reflections and specularity, which often at times seems to break the illusion of the drawing effect. I developed a new class of techniques, using a Barycentric shading method, that allows the non-photorealistic rendering of a variety of artistic drawing styles. My approach can be summarized as follows: (1) a Barycentric shader that can provide generalized crosshatching with opaque multi-textures, (2) a Barycentric shader using transparent multitextures, and (3) a texture synthesis method that can automatically produce crosshatching textures from any given image

Depicting Stylized Materials with Vector Shade Trees

International audienceVector graphics represent images with compact, editable and scalable primitives. Skillful vector artists employ these primitives to produce vivid depictions of material appearance and lighting. However, such stylized imagery often requires building complex multi-layered combinations of colored fills and gradient meshes. We facilitate this task by introducing vector shade trees that bring to vector graphics the flexibility of modular shading representations as known in the 3D rendering community. In contrast to traditional shade trees that combine pixel and vertex shaders, our shade nodes encapsulate the creation and blending of vector primitives that vector artists routinely use. We propose a set of basic shade nodes that we design to respect the traditional guidelines on material depiction described in drawing books and tutorials. We integrate our representation as an Adobe Illustrator plug-in that allows even inexperienced users to take a line drawing, apply a few clicks and obtain a fully colored illustration. More experienced artists can easily refine the illustration, adding more details and visual features, while using all the vector drawing tools they are already familiar with. We demonstrate the power of our representation by quickly generating illustrations of complex objects and materials

A Programmable Model for Designing Stationary 2D Arrangements

This paper introduces a programmable method for designing stationary 2D arrangements for element textures, namely textures made of small geometric elements. These textures are ubiquitous in numerous applications of computer-aided illustration. Previous methods, whether they be example-based or layout-based, lack control and can produce a limited range of possible arrangements. Our approach targets technical artists who will design an arrangement by writing a script.These scripts are using three types of operators: partitioning operators for defining the broad-scale organization of the arrangement, mapping operators for controlling the local organization of elements, and merging operators for mixing different arrangements. These operators are designed so as to guarantee a stationary result meaning that the produced arrangements will always be repetitive. We show that this simple set of operators is sufficient to reach a much broader variety of arrangements than previous methods. Editing the script leads to predictable changes in the synthesized arrangement, which allows an easy iterative design of complex structures. Finally, our operator set is extensible and can be adapted to application-dependent needs

ConTesse: Accurate Occluding Contours for Subdivision Surfaces

International audienceThis paper proposes a method for computing the visible occluding contours of subdivision surfaces. The paper first introduces new theory for contour visibility of smooth surfaces. Necessary and sufficient conditions are introduced for when a sampled occluding contour is valid, that is, when it may be assigned consistent visibility. Previous methods do not guarantee these conditions, which helps explain why smooth contour visibility has been such a challenging problem in the past. The paper then proposes an algorithm that, given a subdivision surface, finds sampled contours satisfying these conditions, and then generates a new triangle mesh matching the given occluding contours. The contours of the output triangle mesh may then be rendered with standard non-photorealistic rendering algorithms, using the mesh for visibility computation. The method can be applied to any triangle mesh, by treating it as the base mesh of a subdivision surface

MeasureIt-ARCH: A Tool for Facilitating Architectural Design in the Open Source Software Blender

This thesis discusses the design and synthesis of MeasureIt-ARCH, a GNU GPL licensed software add-on developed by the author in order to add functionality to the Open Source 3D modeling software Blender that facilitates the creation of architectural drawings. MeasureIt-ARCH adds to Blender simple tools to dimension and annotate 3D models, as well as basic support for the definition and drawing of line work. These tools for the creation of dimensions, annotations and line work are designed to be used in tandem with Blender's existing modelling and rendering tool set. While the drawings that MeasureIt-ARCH produces are fundamentally conventional, as are the majority of the techniques that MeasureIt-ARCH employs to create them, MeasureIt-ARCH does provide two simple and relatively novel methods in its drawing systems. MeasureIt-ARCH provides a new method for the placement of dimension elements in 3D space that draws on the dimension's three dimensional context and surrounding geometry order to determine a placement that optimizes legibility. This dimension placement method does not depend on a 2D work plane, a convention that is common in industry standard Computer Aided Design software. MeasureIt-ARCH also implements a new approach for drawing silhouette lines that operates by transforming the silhouetted models geometry in 4D 'Clip Space'. The hope of this work is that MeasureIt-ARCH might be a small step towards creating an Open Source design pipeline for Architects. A step towards creating architectural drawings that can be shared, read, and modified by anyone, within a platform that is itself free to be changed and improved. The creation of MeasureIt-ARCH is motivated by two goals. First, the work aims to create a basic functioning Open Source platform for the creation of architectural drawings within Blender that is publicly and freely available for use. Second, MeasureIt-ARCH's development served as an opportunity to engage in an interdisciplinary act of craft, providing the author an opportunity to explore the act of digital tool making and gain a basic competency in this intersection between Architecture and Computer Science. To achieve these goals, MeasureIt-ARCH's development draws on references from the history of line drawing and dimensioning within Architecture and Computer Science. On the Architectural side, we make use of the history of architectural drawing and dimensioning conventions as described by Mario Carpo, Alberto Pérez Gómez and others, as well as more contemporary frameworks for the classification of architectural software, such as Mark Bew and Mervyn Richard's BIM Levels framework, in order to help determine the scope of MeasureIt-ARCH's feature set. When crafting MeasureIt-ARCH, precedent works from the field of Computer Science that implement methods for producing line drawings from 3D models helped inform the author’s approach to line drawing. In particular this work draws on the overview of line drawing methods produced by Bénard Pierre and Aaron Hertzmann, Arthur Appel's method for line drawing using 'Quantitative Invisibility', the techniques employed in the Freestyle line drawing system created by Grabli et al. as well as other to help inform MeasureIt-ARCH's simple drawing tools. Beyond discussing MeasureIt-ARCH's development and its motivations, this thesis also provides three small speculative discussions about the implications that an Open Source design tool might have on the architectural profession. We investigate MeasureIt-ARCH's use for small scale architectural projects in a practical setting, using it's tool set to produce conceptual design and renovation drawings for cottages at the Lodge at Pine Cove. We provide a demonstration of how MeasureIt-ARCH and Blender can integrate with external systems and other Blender add-ons to produce a proof of concept, dynamic data visualization of the Noosphere installation at the Futurium center in Berlin by the Living Architecture Systems Group. Finally, we discuss the tool's potential to facilitate greater engagement with the Open Source Architecture (OSArc) movement by illustrating a case study of the work done by Alastair Parvin and Clayton Prest on the WikiHouse project, and by highlighting the challenges that face OSArc projects as they try to produce Open Source Architecture without an Open Source design software