Browsing by Subject "Computer Graphics"
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Item A process for creating Celtic knot work(Texas A&M University, 2004-09-30) Parks, Hunter GuyminCeltic art contains mysterious and fascinating aesthetic elements including complex knot work motifs. The problem is that creating and exploring these motifs require substantial human effort. One solution to this problem is to create a process that collaboratively uses interactive and procedural methods within a computer graphic environment. Spline models of Celtic knot work can be interactively modeled and used as input into procedural shaders. Procedural shaders are computer programs that describe surface, light, and volumetric appearances to a renderer. The control points of spline models can be used to drive shading procedures such as the coloring and displacement of surface meshes. The result of this thesis provides both an automated and interactive process that is capable of producing complex interlaced structures such as Celtic knot work within a three-dimensional environment.Item A Topological Theory of Weaving and Its Applications in Computer Graphics(2013-07-24) Hu, ShiyuRecent advances in the computer graphics of woven images on surfaces in 3-space motivate the development of weavings for arbitrary genus surfaces. We present herein a general framework for weaving structures on general surfaces in 3-space, and through it, we demonstrate how weavings on such surfaces are inducible from connected graph imbeddings on the same surfaces. The necessary and sufficient conditions to identify the inducible weavings in our framework are also given. For low genus surfaces, like plane and torus, we extend our framework to the weavings which are inducible from disconnected imbedded graphs. In particular, we show all weavings on a plane are inducible in our framework, including most Celtic Knots. Moreover, we study different weaving structures on general surfaces in 3-space based on our framework. We show that any weaving inducible in our framework can be converted into an alternating weaving by appropriately changing the strand orders at some crossings. By applying a topological surgery operation, called doubling operation, we can refine a weaving or convert certain non-twillable weavings into twillable weavings on the same surfaces. Interestingly, two important subdivision algorithms on graphs imbeddings, the Catmull-Clark and Doo-Sabin algorithms, correspond nicely to our doubling operation on induced weavings. Another technique we used in studying weaving structures is repetitive patterns. A weaving that can be converted into a twillable weaving by our doubling operation has a highly-symmetric structure, which consists of only two repetitive patterns. An extension of the symmetric structure leads to Quad-Pattern Coverable meshes, which can be seamlessly covered with only one periodic pattern. Both of these two topological structures can be represented with simple Permutation Voltage graphs. A considerable advantage of our model is that it is topological. This permits the graphic designer to superimpose strand colors and geometric attributes ? distances, angles, and curvatures ? that conform to manufacturing or artistic criteria. We also give a software example for plane weaving construction. A benefit of the software is that it supports plane weaving reconstructions from an image of a plane weaving, which could be useful for recording and modifying existing weavings in real life.Item Chinese Painting in 3D: An Artistic Study of the Use of the Traditional Chinese Painting Aesthetic in Three-Dimensional Computer Graphics(2011-02-22) Strickland, Stephanie AnnThis thesis presents a study of both traditional Chinese painting and threedimensional (3D) digital non-photorealistic shading techniques, the results of which are used to create a short animation illustrating an environment that maintains the aesthetic of a Chinese painting while exploring a two-dimensional art style in a new way through camera movement and parallax. Traditional Chinese painting uses alternative methods to communicate depth, such as value range, water-to-ink ratio and vertical placement of objects. In contrast, perspective and parallax are native characteristics of 3D digital technology and are easily generated using a virtual camera. When combining these two mediums to inject linear perspective into the Chinese painting style, it is equally important to maintain the integrity of the aesthetic by adhering to the stylistic and compositional rules throughout the animation. As a result, the final project may be paused at many key frames and appear to follow these rules closely. This study also describes the methodology of translating the Chinese painting aesthetic into a 3D digital medium, which can also be used in the interpretation of other traditional art styles.Item Duotone Surfaces: Division of a Closed Surface into Exactly Two Regions(2013-04-22) Garigipati, PradeepIn this thesis work, our main motivation is to create computer aided art work which can eventually transform into a sculpting tool. The work was inspired after Taubin?s work on constructing Hamiltonian triangle strips on quadrilateral meshes. We present an algorithm that can divide a closed 2-manifold surface into exactly two regions, bounded from each other by a single continuous curve. We show that this kind of surface division is possible only if the mesh approximation of a given object is a two colorable quadrilateral mesh. For such a quadrilateral mesh, appropriate texturing of the faces of the mesh using a pair of Truchet tiles will give us a Duotone Surface. Catmull-Clark subdivision can convert any given mesh with arbitrary sided polygons into a two colorable quadrilateral mesh. Using such vertex insertion schemes, we modify the mesh and classify the vertices of the new mesh into two sets. By appropriately texturing each face of the mesh such that the color of the vertices of the face match with the colored regions of the corresponding Truchet tile, we can get a continuous curve that splits the surface of the mesh into two regions. Now, coloring the thus obtained two regions with two different colors gives us a Duotone Surface.Item Implementing autonomous crowds in a computer generated feature film(Texas A&M University, 2006-04-12) Patterson, John AndreThe implementation of autonomous, flocking crowds of background characters in the feature film ??Robots?? is discussed. The techniques for obstacle avoidance and goal seeking are described. An overview of the implementation of the system as part of the production pipeline for the film is also provided.Item Modeling high-genus surfaces(Texas A&M University, 2004-09-30) Srinivasan, VinodThe goal of this research is to develop new, interactive methods for creating very high genus 2-manifold meshes. The various approaches investigated in this research can be categorized into two groups -- interactive methods, where the user primarily controls the creation of the high-genus mesh, and automatic methods, where there is minimal user interaction and the program automatically creates the high-genus mesh. In the interactive category, two different methods have been developed. The first allows the creation of multi-segment, curved handles between two different faces, which can belong to the same mesh or to geometrically distinct meshes. The second method, which is referred to as ``rind modeling'', provides for easy creation of surfaces resembling peeled and punctured rinds. The automatic category also includes two different methods. The first one automates the process of creating generalized Sierpinski polyhedra, while the second one allows the creation of Menger sponge-type meshes. Efficient and robust algorithms for these approaches and user-friendly tools for these algorithms have been developed and implemented.Item Scales and Scale-like Structures(2011-08-08) Landreneau, Eric BenjaminScales are a visually striking feature that grows on many animals. These small, rigid plates embedded in the skin form an integral part of our description of ?sh and reptiles, some plants, and many extinct animals. Scales exist in many shapes and sizes, and serve as protection, camou?age, and plumage for animals. The variety of scales and the animals they grow from pose an interesting problem in the ?eld of Computer Graphics. This dissertation presents a method for generating scales and scale-like structures on a polygonal mesh through surface replacement. A triangular mesh was covered with scales and one or more proxy-models were used as the scales shape. A user began scale generation by drawing a lateral line on the model to control the distribution and orientation of scales on the surface. Next, a vector ?eld was created over the surface to control an anisotropic Voronoi tessellation, which represents the region occupied by each scale. Then these regions were replaced by cutting the proxy model to match the boundary of the Voronoi region and deform the cut model onto the surface. The ?nal result is a fully connected 2-manifold that is suitable for subsequent post-processing applications, like surface subdivision.Item Visualization tools for moving objects(Texas A&M University, 2006-04-12) Vargas Estrada, AimeeIn this work we describe the design and implementation of a general framework for visualizing and editing motion planning environments, problem instances, and their solutions. The motion planning problem consists of finding a valid path between a start and a goal configuration for a movable object. The workspace is, in traditional robotics and animation applications, composed of one or more objects (called obstacles) that cannot overlap with the robot. As even the simplest motion planning problems have been shown to be in- tractable, most practical approaches to motion planning use randomization and/or compute approximate solutions. While the tool we present allows the manipulation and evaluation of planner solutions and the animation of any path found by any plan- ner, it is specialized for a class of randomized planners called probabilistic roadmap methods (PRMs). PRMs are roadmap-based methods that generate a graph or roadmap where the nodes represent collision-free configurations and the edges represent feasible paths between those configurations. PRMs typically consist of two phases: roadmap con- struction, where a roadmap is built, and query, where the start and goal configura- tions are connected to the roadmap and then a path is extracted using graph search techniques.