Thesis (Ph. D.)--University of Washington. / Vita. Bibliography: L. [170]-183.

Thesis (M.S.)--University of California, Santa Cruz, 1998. / Typescript. Includes bibliographical references (leaves 49-51).

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

In this dissertation, we first introduce an equal-area spherical map, HEALPix, which is borrowed from astrophysics. Its associated sample pattern is uniformly distributed over the sphere surface. Then we discuss its application in environment mapping. Although the HEALPix representation is more balanced than the traditional cubemap, it cannot utilize the built-in hardware operations like cubemap, and the mipmapping construction is more complicated. Therefore, its rendering speed is not comparable to that of the cubemap. This motivates us to invent a new six-face spherical map, called isocube. Unlike cubemap, isocube is an equal-area mapping, i.e., each texel spans the same area and is equally important. Due to the six-face representation, isocube can fit nicely into the cubemap hardware and hence can fully exploit the hardware operations tailored for cubemap. In addition, its mapping computation only involves a small overhead. Therefore the look-up speed for isocube is very fast. / Next we discuss another application of HEALPix map, the dynamic environment sequence sampling. Previous work only considers the static case where the environment map is approximated by finite directional light sources. In the dynamic case, the individual regeneration of samples for each frame may introduce abrupt, changes in the rendering animation. To handle this temporal inconsistency problem, we propose spherical q2-tree based on IIEALPix map. The adaptiveness of the quadtree can suppress the abrupt changes between consecutive frames, and hence a rather smooth rendering can be produced. This method, however, generates sample pattern independently for each environment frame, and therefore it may still cause unexpected, lumps in some situations. To fully utilize the temporal coherence in the sequence, we present a global sampling approach which treats the dynamic environment sequence as a all volume and performs sampling in the volume. The volumetric sampling adapts the sample number according to each frame and restricts the temporal/spatial changes within small subdivided volumes, and hence ensures a smooth sampling sequence. Within the framework, we present a volumetric importance metric and develop a binary-quad tree to perform stratification. Experimental results show that our volumetric sampling method can generate light samples with a better temporal consistency. / Spherical map is the foundation for many applications in computer graphics, such as environment mapping, precomputed radiance transfer, radiosity and image-based rendering. For these applications that involve intensive computation on spherical domain, it is generally desirable to employ equal-area and uniform spherical maps as the underlying parameterization. However, equal-area spherical maps are less exploited in graphics. / Wan, Liang. / "August 2007." / Adviser: Tien-Tsin Wong. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1121. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 118-123). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

This paper reports the design and development of an underwater laser scanning system to measure the geometry of underwater objects. The application of structure light scanning method requires a calibrated CCD camera as the input device. Because the underwater environment is by far different from that in the air. Conventional calibration methods adopted in the air can not be applied for the underwater cases. In this paper we propose an algorithm which is analogous to the idea of longitudes/latitude in map projection to calibration the CCD. The calibration board pattern is fabricated by laying vertical and horizontal grid dots of 5cm span with an NC milling machine. To obtain the higher accuracy, we redesign the laser source holder to make the board and laser scan line coplane. We use a new laser that is focus adjustable. So we can capture clearer image of the edge on the target. Then, we calibrate the CCD camera with the calibration board. For testing our new system, two test pieces are used. One is sine waves ripples with varying amplitudes from 8mm to 3 mm. The other one is a rough surface with know spatial power spectrum. Scanning results show that: Scanning from rough 1 meter away, the absolute error for the sine wave ripples is less than 1mm along vertical direction. The power spectrum for the rough surface is accurate to the order of 3 to 5mm wave number. In order to survive in the harsh underwater environment, we design and make a rotational scanning system. The system was designed as an automatic image-capturing system, utilizing single board computer as control plane to work in conjunction with PLC(Programmable Logic Controller) for System power management. When using two 12V batteries as main power source, obtaining samples once per hour, capturing 360 images per operation, the system may run for approximately 39 hours.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 95-100). Also available via the Internet.