Patternshop: Editing Point Patterns by Image Manipulation

Point patterns are characterized by their density and correlation. While spatial variation of density is well-understood, analysis and synthesis of spatially-varying correlation is an open challenge. No tools are available to intuitively edit such point patterns, primarily due to the lack of a compact representation for spatially varying correlation. We propose a low-dimensional perceptual embedding for point correlations. This embedding can map point patterns to common three-channel raster images, enabling manipulation with off-the-shelf image editing software. To synthesize back point patterns, we propose a novel edge-aware objective that carefully handles sharp variations in density and correlation. The resulting framework allows intuitive and backward-compatible manipulation of point patterns, such as recoloring, relighting to even texture synthesis that have not been available to 2D point pattern design before. Effectiveness of our approach is tested in several user experiments.Comment: 14 pages, 16 figure

The relationship between the creation and perception of art

It is suggested that similar cognitive processes are involved with both the creation and perception of art. However, a lack of research examines this relationship, whether this is just from the perspective of the artist, or in relation to the artist and perceiver of the final product. To do so, we examined the experience of artists and non‐artists investigating initial stages of art‐making by examining relationships between aesthetic and drawing preferences of geometric stimuli (Experiments 1 & 2). To further understand this experience, we allowed artists and non‐artists to be involved in actual drawing activity (stippling and stroking) whilst making drawing preferences. We also examined how being involved in drawing influenced aesthetic preferences (Experiment 3), this led to conducting studies considering perceivers (artists/non‐artists) of artworks. Here, we investigated how congruent actions (simultaneously produced or learnt during pre‐training) with the artists behind the artwork influenced aesthetic responses (Experiments 4 & 5). Examination of gaze behaviour throughout these studies provides further insight into the aesthetic experience by revealing the processes behind formations of judgements. Overall, we conclude that there are similarities between experiences (gaze and judgments) involved in the creation and perception of art. We find similarities between aesthetic and drawing preferences and find gaze to be impacted in a similar manner when observing images in comparison to making a drawing choice. We do not provide support that these drawing choices are influenced by being involved with drawing but do show that the more experience a perceiver receives with these actions of the artist the more their aesthetic judgements are influenced by these, supporting the relationship between artist and perceiver depicted in the mirror model of art. We provide a foundation for future research to empirically analyse connections between the creation and perception of art and the relationships between the artist and perceiver

Improving the Tractography Pipeline: on Evaluation, Segmentation, and Visualization

Recent advances in tractography allow for connectomes to be constructed in vivo. These have applications for example in brain tumor surgery and understanding of brain development and diseases. The large size of the data produced by these methods lead to a variety problems, including how to evaluate tractography outputs, development of faster processing algorithms for tractography and clustering, and the development of advanced visualization methods for verification and exploration. This thesis presents several advances in these fields. First, an evaluation is presented for the robustness to noise of multiple commonly used tractography algorithms. It employs a Monte–Carlo simulation of measurement noise on a constructed ground truth dataset. As a result of this evaluation, evidence for obustness of global tractography is found, and algorithmic sources of uncertainty are identified. The second contribution is a fast clustering algorithm for tractography data based on k–means and vector fields for representing the flow of each cluster. It is demonstrated that this algorithm can handle large tractography datasets due to its linear time and memory complexity, and that it can effectively integrate interrupted fibers that would be rejected as outliers by other algorithms. Furthermore, a visualization for the exploration of structural connectomes is presented. It uses illustrative rendering techniques for efficient presentation of connecting fiber bundles in context in anatomical space. Visual hints are employed to improve the perception of spatial relations. Finally, a visualization method with application to exploration and verification of probabilistic tractography is presented, which improves on the previously presented Fiber Stippling technique. It is demonstrated that the method is able to show multiple overlapping tracts in context, and correctly present crossing fiber configurations

“It Washes Through”: Fibre Art and the Intertidal Zone in Contemporary Nova Scotia

This thesis investigates land-based fibre art practices that are carried out in the intertidal zones in the province of Nova Scotia, and the potential for such practices to generate an ecological worldview. To do so, the following pages focus on the processes of three artists, Alexa Bunnell, Doug Guildford, and Katrina Craig, who have all recently used fibre-based practices to engage with the specific character of the intertidal zones. This thesis weaves together evidence from secondary sources with primary material drawn from conversational interviews with the artists. My methodology draws from the diversity of approaches, including critical craft studies, ecocriticism, and new materialism. This thesis briefly analyses different models for engaging with the landscape that were used in the Earth Art movement of the 60s and 70s, in order to locate a process that aligns with Tim Morton’s definition of developing “ecological awareness.” The body of this thesis analyses the themes that arose in the interviews. Firstly, the important role that bodies, materials and environments take in developing self-awareness and ecological awareness, as well as the unique traits of fibre-based processes that lend themselves to this process. Another section inquiries into the way Guildford, Bunnell, and Craig’s work hybridised the technical and artistic applications of fibre art. The last section explores the element of storytelling that takes place through their work, which lends itself to generating an ecological paradigm. I contend that Bunnell, Guildford, and Craig’s art-making processes raise ecological awareness beyond the realm of art, in an exchange that social anthropologist Tim Ingold describes as “textility.” This creative modality allows these artists to contribute to generating an ecological paradigm

Synthesis and evaluation of geometric textures

Two-dimensional geometric textures are the geometric analogues of raster (pixel-based) textures and consist of planar distributions of discrete shapes with an inherent structure. These textures have many potential applications in art, computer graphics, and cartography. Synthesizing large textures by hand is generally a tedious task. In raster-based synthesis, many algorithms have been developed to limit the amount of manual effort required. These algorithms take in a small example as a reference and produce larger similar textures using a wide range of approaches. Recently, an increasing number of example-based geometric synthesis algorithms have been proposed. I refer to them in this dissertation as Geometric Texture Synthesis (GTS) algorithms. Analogous to their raster-based counterparts, GTS algorithms synthesize arrangements that ought to be judged by human viewers as “similar” to the example inputs. However, an absence of conventional evaluation procedures in current attempts demands an inquiry into the visual significance of synthesized results. In this dissertation, I present an investigation into GTS and report on my findings from three projects. I start by offering initial steps towards grounding texture synthesis techniques more firmly with our understanding of visual perception through two psychophysical studies. My observations throughout these studies result in important visual cues used by people when generating and/or comparing similarity of geometric arrangements as well a set of strategies adopted by participants when generating arrangements. Based on one of the generation strategies devised in these studies I develop a new geometric synthesis algorithm that uses a tile-based approach to generate arrangements. Textures synthesized by this algorithm are comparable to the state of the art in GTS and provide an additional reference in subsequent evaluations. To conduct effective evaluations of GTS, I start by collecting a set of representative examples, use them to acquire arrangements from multiple sources, and then gather them into a dataset that acts as a standard for the GTS research community. I then utilize this dataset in a second set of psychophysical studies that define an effective methodology for comparing current and future geometric synthesis algorithms

Designing Digital Art and Communication Tools Inspired by Traditional Craft

Ph.DDOCTOR OF PHILOSOPH

The Sublime, an empirical investigation

The sublime has occupied a special space in aesthetic theory since Burke’s classic A Philosophical Enquiry into the Origin of Our Ideas of the Sublime and Beautiful of 1757, referring to a group of aesthetic experiences associated with magnitude and power. Despite recent use of the term in general psychology, there is a lack of empirical characterisation of the sublime, especially in relation to beauty. Our exploratory work addresses these issues: (1) to understand the physical characteristics of items judged as sublime, (2) to understand underlying emotional and cognitive factors of the sublime and (3) to understand the role of individual differences. Study 1 was an image rating task in which participants rated a wide range of natural images on their degree of the sublime and beauty. Study 2 was a word-association task, with words taken from a corpus of aesthetic-related and sublime-related adjectives/phrases being rated in terms of their perceived associations with the sublime and the beautiful. Results demonstrate that there are physical and psychological properties associated uniquely with the sublime, and that individual differences may play an important role. The current results provide insight into the literature of the sublime, and have implications on recent trends of emotional and environmental psychology

Reconsidering light transport : acquisition and display of real-world reflectance and geometry

In this thesis, we cover three scenarios that violate common simplifying assumptions about the nature of light transport. We begin with the first ingredient to any çD rendering: a geometry model. Most çD scanners require the object-of-interest to show diffuse refectance. The further a material deviates from the Lambertian model, the more likely these setups are to produce corrupted results. By placing a traditional laser scanning setup in a participating (in particular, fuorescent) medium, we have built a light sheet scanner that delivers robust results for a wide range of materials, including glass. Further investigating the phenomenon of fluorescence, we notice that, despite its ubiquity, it has received moderate attention in computer graphics. In particular, to date no datadriven reflectance models of fluorescent materials have been available. To describe the wavelength-shifling reflectance of fluorescent materials, we define the bispectral bidirectional reflectance and reradiation distribution function (BRRDF), for which we introduce an image-based measurement setup as well as an efficient acquisition scheme. Finally, we envision a computer display that showsmaterials instead of colours, and present a prototypical device that can exhibit anisotropic reflectance distributions similar to common models in computer graphics.In der Computergraphik und Computervision ist es unerlässlich, vereinfachende Annahmen über die Ausbreitung von Licht zumachen. In dieser Dissertation stellen wir drei Fälle vor, in denen diese nicht zutreffen. So wird die dreidimensionale Geometrie von Gegenständen oft mit Hilfe von Laserscannern vermessen und dabei davon ausgegangen, dass ihre Oberfläche diffus reflektiert. Dies ist bei den meisten Materialien jedoch nicht gegeben, so dass die Ergebnisse oft fehlerhaft sind. Indem wir das Objekt in einem fluoreszierenden Medium einbetten, kann ein klassischer CD-Scanner-Aufbau so modifiziert werden, dass er verlässliche Geometriedaten für Objekte aus verschiedensten Materialien liefert, einschließlich Glas. Auch die akkurate Nachbildung des Aussehens von Materialien ist wichtig für die photorealistische Bildsynthese. Wieder interessieren wir uns für Fluoreszenz, diesmal allerdings für ihr charakteristisches Erscheinungsbild, das in der Computergraphik bislang kaum Beachtung gefunden hat. Wir stellen einen bildbasierten Aufbau vor, mit dem die winkel- und wellenlängenabhängige Reflektanz fluoreszierender Oberflächen ausgemessen werden kann, und eine Strategie, um solche Messungen effizient abzuwickeln. Schließlich befassen wir uns mit der Idee, nicht nur Farben dynamisch anzuzeigen, sondern auch Materialien und ihr je nach Lichteinfall und Blickwinkel unterschiedliches Aussehen. Einer generellen Beschreibung des Problems folgt die konkrete Umsetzung in Formzweier Prototypen, die verschiedene Reflektanzverteilungen auf einer Oberfläche darstellen können