One of our basic senses is the ability to visually perceive our environment and what is around us. In the spatial sense, a single frame or image can depict opaque materials which offer the outermost layer of the objects as well as translucent ones which show us the inner structures and thus contribute more to our understanding of shapes. In the temporal sense, we can also explore the possibility of presenting different time instances of objects simultaneously in order to better understand a scene or event. In this thesis, we focus on multiple visibility techniques in both the spatial and temporal domains.

To address a fundamental rendering problem of spatial visibility, we propose two novel schemes for real-time rendering of static 3D models front-to-back or back-to-front relati...[ Read more ]

One of our basic senses is the ability to visually perceive our environment and what is around us. In the spatial sense, a single frame or image can depict opaque materials which offer the outermost layer of the objects as well as translucent ones which show us the inner structures and thus contribute more to our understanding of shapes. In the temporal sense, we can also explore the possibility of presenting different time instances of objects simultaneously in order to better understand a scene or event. In this thesis, we focus on multiple visibility techniques in both the spatial and temporal domains.

To address a fundamental rendering problem of spatial visibility, we propose two novel schemes for real-time rendering of static 3D models front-to-back or back-to-front relative to any viewpoint. Both methods are a significant departure from previous work and are significantly faster at run-time when compared with other approaches. Our approaches render depth-sorted triangles using a single draw-call. The first approach, referred to as depth-presorted triangle lists, replaces the traditional sorting strategy of existing algorithms with a faster triangle selection strategy at run-time. The selection process operates on an extended sequence of triangles annotated by test planes, created by our off-line preprocessing stage. Based on these test planes, a simple run-time procedure uses the given viewpoint to select a subsequence of triangles for rasterization. Selected subsequences are statically presorted by the depth and contain each input triangle exactly once. The second approach, referred to as triangle lists clustering, comes up with a divide-and-merge scheme in which to find several triangle lists representable for all the sampled views. At run-time, the approach simply selects the correct triangle lists without any further sorting or selection. The selected triangle lists would provide accurate or approximated depth sorted results based on the preprocessing. The approximated solution comes up with a fewer total number of the triangle lists and renders with limited visual errors compare with an accurate one. Both our methods run on legacy hardware and render depth-sorted static models significantly faster than previous approaches. We conclude by demonstrating the real-time rendering of order-independent transparency effects.

In the realm of temporal visibility, we propose a new media visualization format - referred to as Replates - to experience replays of video clips, especially for sporting events. In the same spatial frame, we are able to combine different temporal snapshots while preserving temporal continuity and emphasizing on the key events in the scene. We use computer vision tools, such as camera tracking and background subtraction, to align all frames in the original video with regard to each other. Using this alignment, we create a single plate as it would be seen from a wide-angle static camera. Key players and events are then reinserted into this arena, recovering the big picture that is typically lost due to camera panning and zoom. Replates are played in a continuous loop. We allow replate authors to include multiple instances of each player, offset by regular intervals, so viewers can quickly and repeatedly inspect their favorite moments. Authors can also choose from a variety of effects that help them construct a narrative of their favorite plays. Replates take a fraction of the size of the original input video and produce an effect reminiscent of video game reenactments of famous sporting events. The footage, however, is real.