Amy Ashurst Gooch

Effects of stereo viewing conditions on distance perception in virtual environments

Several studies from different research groups investigating perception of absolute, egocentric distances in virtual environments have reported a compression of the intended size of the virtual space. One potential explanation for the compression is that inaccuracies and cue conflicts involving stereo viewing conditions in head mounted displays result in an inaccurate absolute scaling of the virtual world. We manipulate stereo viewing conditions in a head mounted display and show the effects of using both measured and fixed inter-pupilary distances, as well as bi-ocular and monocular viewing of graphics, on absolute distance judgments. Our results indicate that the amount of compression of distance judgments is unaffected by these manipulations. The equivalent performance with stereo, bi-ocular, and monocular viewing suggests that the limitations on the presentation of stereo imagery that are inherent in head mounted displays are likely not the source of distance compression reported in previous virtual environment studies.

Abstraction of man-made shapes

Man-made objects are ubiquitous in the real world and in virtual environments. While such objects can be very detailed, capturing every small feature, they are often identified and characterized by a small set of defining curves. Compact, abstracted shape descriptions based on such curves are often visually more appealing than the original models, which can appear to be visually cluttered. We introduce a novel algorithm for abstracting three-dimensional geometric models using characteristic curves or contours as building blocks for the abstraction. Our method robustly handles models with poor connectivity, including the extreme cases of polygon soups, common in models of man-made objects taken from online repositories. In our algorithm, we use a two-step procedure that first approximates the input model using a manifold, closed envelope surface and then extracts from it a hierarchical abstraction curve network along with suitable normal information. The constructed curve networks form a compact, yet powerful, representation for the input shapes, retaining their key shape characteristics while discarding minor details and irregularities.

The aesthetics of graph visualization

The discipline of graph visualization produces pictorial representations of node–link structures. Much effort has been directed toward making such diagrams visually pleasing. A variety of aesthetic heuristics have been proposed, with the assumption that these will improve readability and understanding. We look at a perceptual basis for these heuristics, including Gestalt principles and Normans emotional design framework. Next, we review the work to date on aesthetic heuristics and examine what has been done to evaluate these heuristics. We summarize this in a framework that outlines graph drawing heuristics, their perceptual basis, and evaluation status.

The impact of game design on students' interest in CS

We examine the effect of game design on students attitudes, specifically interest in attaining a Computer Science degree, continued development of programming skills and experience in game design. Students in a Computer Science Survey course are given the task of applying software engineering principles in the context of game design. Using the Game Maker platform, students are divided into teams and participate in collaborative game design for 2.5 weeks. Pre and post survey results reveal that game design can have both a positive and negative impact on students attitudes about Computer Science, game design and further development of programming skills. Furthermore, it is imperative that assignments are carefully planned and cover appropriate material in respect to time constraints if the goal is to positively influence students attitudes and lead to positive learning outcomes.

Viewing progress in non-photorealistic rendering through Heinlein's lens

The field of non-photorealistic rendering is reaching a mature state. In its infancy, researchers explored the mimicry of methods and tools used by traditional artists to generate works of art, through techniques like watercolor or oil painting simulations. As the field has moved past mimicry, ideas from artists and artistic techniques have been adapted and altered for performance in the media of computer graphics, creating algorithmic aesthetics such as generative art or the automatic composition of objects in a scene, as well as abstraction in rendering and geometry. With these two initial stages of non-photorealistic rendering well established, the field must find new territory to cover. In this paper, we provide a high level overview of the past and current state of non-photorealistic rendering and call to arms the community to create the areas of research that make computation of non-photorealistic rendering generate never before realized results.

Computational Aesthetics 2008: Automatically mimicking unique hand-drawn pencil lines

In applications such as architecture, early design sketches containing accurate line drawings often mislead the target audience. Approximate human-drawn sketches are typically accepted as a better way of demonstrating fundamental design concepts. To this end we have designed an algorithm that creates lines that perceptually resemble human-drawn lines. Our algorithm works directly with input point data and a physically based mathematical model of human arm movement. Our algorithm generates unique lines of arbitrary length given the end points of a line, without relying on a database of human-drawn lines. We found that an observational analysis obtained through various user studies of human lines made a bigger impact on the algorithm than a statistical analysis. Additional studies have shown that the algorithm produces lines that are perceptually indistinguishable from that of a hand-drawn straight pencil line. A further expansion to the system resulted in mimicked dashed lines.

Investigating studio-based learning in a course on game design

Jobs in the computing field demand communication and teamwork skills in addition to programming skills. Focus at the undergraduate level needs to be shifted towards developing these collaborative skills to enable a more smooth transition into employment in industry. The University of Victoria is in its second year of offering a course on game design. In the first offering, new activities were introduced to address issues identified by recent studies on university graduates entering industry. We focused on integrating cooperative learning, group orientation, and peer review activities into the game design process. The course attracted students across multiple disciplines, and an analysis indicated increased student interest in pursuing a computer science degree. Unfortunately, the same pre- and post-surveys suggested that our collaborative activities may have resulted in a decrease in student interest regarding course work and in pursuing studies in game design. In this paper we report on how we used a studio-based pedagogical approach to restructure the peer review activities in our course. In our previous offering, students received peer feedback only on their final game presentation. In our latest offering, we integrated peer review activities into every step of the game development process, allowing students to refine their ideas while progressing through a game project. A quantitative analysis informs us that our refined peer review activities were successful in increasing student presentation confidence, sense of community, and excitement towards their course projects.

Addressing industry issues in a multi-disciplinary course on game design

Over the past few years, games courses have been gaining in popularity, as there has been growing evidence showing positive enrollment and student engagement results. Nevertheless, new graduates still lack critical teamwork and problem-solving skills required by industry employers. Building upon other game programs that had successful results, we present a game design course developed to attract students of all disciplines. Our course is different because we focus on three main issues directly associated with new graduates entering industry: cooperative learning, peer review, and orientation with a pre-existing large code base. A quantitative analysis reveals both a positive and negative impact on students interests, in particular within a cohort of non-Computer Science majors. A qualitative analysis reveals the ways in which students were influenced by a course design where assessment was aligned with key industry issues.

Resolution Independent NPR‐Style 3D Line Textures

This work introduces a technique for interactive walk‐throughs of non‐photorealistically rendered (NPR) scenes using three‐dimensional (3D) line primitives to define architectural features of the model, as well as indicate textural qualities. Line primitives are not typically used in this manner in favour of texture mapping techniques which can encapsulate a great deal of information in a single texture map, and take advantage of GPU optimizations for accelerated rendering. However, texture mapped images may not maintain the visual quality or aesthetic appeal that is possible when using 3D lines to simulate NPR scenes such as hand‐drawn illustrations or architectural renderings. In addition, line textures can be modified interactively, for instance changing the sketchy quality of the lines. The technique introduced here extracts feature edges from a model, and using these edges, generates a reduced set of line textures which indicate material properties while maintaining interactive frame rates. A clipping algorithm is presented to enable 3D lines to reside only in the interior of the 3D model without exposing the underlying triangulated mesh. The resulting system produces interactive illustrations with high visual quality that are free from animation artifacts.

Morphable guidelines for the human head

We present a system to help users achieve better face warping on 2D portrait images. Faces can be difficult to warp accurately because the rotation of the head affects the shape of the facial features. We bypass this problem by utilizing the Loomis ball and plane head drawing method as a proxy structure. The resulting morphable guidelines consist of a simple 3D head model. This proxy model can be reshaped by the user to mimic the positioning and proportions of a face in their input image. The vertices of the model act as deformation points for a 2D image deformation algorithm. Thus, the user can seamlessly transform the face proportions in the 2D image by transforming the proportions of the morphable guidelines. This technique can be used for both retouching and caricature warping purposes, as it is well-suited for both subtle and extreme modifications. Our system is advantageous over previous work in face warping because our morphable guidelines can be used on a wide range of head orientations and do not require the generation and reintegration of a full 3D model.