Master of Science

Design form choices and information visualization outcomes remain inexhaustible, and they result from ongoing judgments about their appropriateness or effectiveness. Visualization design decision models have been widely proposed and applied. However, experts fail to explicitly study using design judgment to produce informed, professional decisions. In this dissertation, I bridge design form informational judgment gap when analyzing five studies with lab and in-situ designs individually as well as cross-case synthetically and comparably to examine the design judgments of all students working with visualization projects. The outcome stands to explain comprehensively how these student designers make judgments throughout their design process. Through analyzing several design cases, I identify the judgments enabling design moves forward and outcomes. The findings provide a robust description of designers’ design judgment activities and how the design judgment methods relate to design outcomes. These findings may also help identify gaps in information visualization education.<br>

Open-world video games give players a large environment to explore along with increased freedom to navigate and manipulate that environment. These requirements pose several problems that must be addressed by a game's graphics engine. Often there are a large number of visible objects, such as all of the trees in a forest, as well as objects comprised of large amounts of geometry, such as terrain. An open-world graphics engine must be able to render large environments at varying levels of detail and smoothly transition between detail levels to provide a believable experience. Often this involves finding a way to both store and generate the large amounts of geometry that represent the environment. In this thesis we present a system for generating and rendering large exterior environments, with a focus on terrain and vegetation. We use a region-based procedural generation algorithm to create environments of varying types. This algorithm produces content that can be rendered at multiple levels of detail. The terrain is rendered volumetrically to support caves, overhangs, and cliffs, but is also rendered using heightmaps to allow for large view distances. Vegetation is implemented using procedurally generated meshes and impostors. The volumetric terrain is editable in real time, which limits our ability to pre-generate or cache large amounts of geometry, and also limits the number of assumptions we can make with regard to visibility. We support a view distance of at least 25 miles in each direction, though distant objects are rendered at low resolution. The heightmap terrain used to achieve this view distance consists of over 360,000 triangles. Our system runs at 180 frames per second on commodity desktop hardware.

Master of Science

The realistic animation of virtual characters can enhance user experience. Motion-editing methods such as keyframing and motion capture are effective for pre-determined animations but are incapable of real-time generation. Algorithm-based dynamic simulation and machine learning-based motion synthesis are procedural but too complex. This thesis explores an approach known as animation interpolation, which benefits from the strengths of both types of methods. Animation interpolation generates full animation sequences by assembling pre-defined motion primitives or key poses in real-time. <div><br></div><div>The purpose of this thesis is to evaluate the naturalness of character animation in three common interpolation methods: linear Euler interpolation, spherical linear quaternion interpolation, and spherical spline quaternion interpolation. Many researchers have studied the mathematical equations, motion curves, and velocity graphs of these algorithms. This thesis focuses on the perceptual evaluation and the implementation of expressive upper body character animation. </div><div><br></div><div>During the experimental studies, 97 participants watched 12 animation clips of a character performing four different upper body motions using three interpolation methods. The motions were based on McNeill’s classification of body gestures (beat gesture, deictic gesture, iconic gesture, and metaphoric gesture). After viewing each clip, the participants rated the naturalness on a 5-point Likert scale. The results showed that animations generated using spherical spline quaternion interpolation were perceived as significantly more natural than those generated from the other two interpolation methods.</div>

A common practice in crowd animation is the use of human templates. A human template is a 3D character defined by its mesh, skeletal structure, materials, and textures. A crowd simulation is created by repeatedly instantiating a small set of human templates. For each instance, one texture is randomly chosen from the template’s available texture set, and color and shape variety techniques are applied so that multiple instances of the same template appear different (Thalmann & Musse, 2013). When dealing with very large crowds, it is inevitable to end up with instances that are exactly identical to other instances, as the number of different textures and shape modifications is limited. This poses a problem for crowd animation, as the viewers’ perception of identical characters could significantly decrease the believability of the crowd simulation. A variety of factors could affect viewers’ perception of identical characters, including crowd size, distance of the characters from the camera, background, movement, lighting conditions, etc. The study reported in this paper examined the extent to which the type of locomotion of the crowd characters affects the viewer’s ability to perceive identical instances within a medium size crowd (20 characters). The experiment involved 51 participants and compared the time the participants took to recognize two identical characters in three different locomotion scenarios (i.e. standing, walking, and running). Findings show that the type of locomotion did not have a statistically significant effect on the time subjects took to identify identical characters within the crowd. Hence, results suggest that audience perception of identical characters in a medium size crowd is not affected by the type of movement of the characters.

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