Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 127-141).

Thesis (Ph.D.) in Spatial Information Science and Engineering--University of Maine, 2005. / Includes vita. Includes bibliographical references (leaves 146-164).

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 56.

Thesis (doctoral)--Lunds Universitet, Malmö, 1988. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

A leg ulcer is a chronic wound of the skin that, at best, takes many months to fully heal and causes great distress to the patient. Treating leg ulcers places a large financial burden upon the National Health Service in the United Kingdom, estimated to be in excess of £300M annually. Measurement of the size of leg ulcers is a guide to assessing the progress of wound healing, and the use of non-invasive measurement techniques avoids damaging or infecting the wound. The area of a leg ulcer is currently measured by presenting a human observer with a captured video image of a wound, who then uses a mouse or pointing device to delineate the wounded region. Typically, the standard deviation of area measurements taken this way is approximately 5% of the wound area. In addition, different observers can show a bias difference in their area measurements from 3% to 25% of the wound area. It is proposed to reduce the incidence of such errors by using an active contour model to improve the delineation. Four different models are developed by adapting and applying several contributions made to the active contour model paradigm. Novel features include an external force that acts normally, but not tangentially, to the boundary, a new external energy term that promotes homogeneity of the gray level at the edge of the wound and the application of the minimax principle for setting the parameters of an active contour model with piecewise b-spline curves. The algorithms provide the physician with a new and practical tool for producing area measurements with improved precision and are semi-automatic, requiring only a manual delineation to start the algorithm. In most cases, measurement precision is improved by application of the algorithms. Many wounds give rise to measurable bias differences between average manual area measurements and the corresponding algorithmic area measurements, typically averaging 3% to 4% of wound area. With some wounds the bias magnitude can exceed 10% as a result of the contour partly deviating from the true edge of the wound and following a false edge.

This dissertation presents original computer vision algorithms to automate the identification of piping and photogrammetric piping features in individual digital images of industrial installations. Automatic identification of the pixel regions associated with piping is the core original element of this work and is accomplished through a re-representation of image information (light intensity versus position) in a light intensity versus gradient orientation data space. This work is based on the physics of scene illumination/reflectance and evaluates pixel regions in a hierarchy of data abstractions to identify pipe regions without needing specific information about pipe edges, illumination, or reflectance characteristics. The synthesis of correlated information used in this image segmentation algorithm provides a robust technique to identify potential pipe pixel regions in real images. An additional unique element of this work is a pipe edge identification methodology, which uses the information from this light intensity versus gradient orientation data space to localize the pipe edge search space (in both a pixel position and gradient orientation sense). This localization provides a very specific, perspective independent, self-adaptive pipe edge filter. Pipe edges identified in this manner are then incorporated into a robust region joining algorithm to address the issue of region fragmentation (caused by occluding components and shadows). Automated photogrammetric feature identification is also demonstrated through algorithmically recognizing the intersection of orthogonal pipe sections (with piping code acceptable diameter ratios) as potential T-junctions or 90-degree elbows. As pipe intersections, these image points are located with sub pixel resolution even though they cannot be identified by simple inspection. The computer vision algorithms of this dissertation are robust physics based methods, applicable to the identification of piping and photogrammetric pipe features in real world images of industrial installations, being: perspective independent, albedo independent, and unaffected by inter-reflections. Automating these operator driven input tasks will improve the accuracy, ease-of-use, and cost effectiveness of implementing existing photogrammetric programs to the significant industrial problem of generating as-built piping drawings. / Graduate

Photogrammetry has become increasingly important in the practice of forestry. Recently, the trend has been toward the development of photo-mensurational techniques for direct estimation of timber resources. The purpose of the present study was to assess the possibility of applying aerial stand-volume multiple-regression equations for the application of photo-mensurational techniques on several kinds of air photos. Field data were collected from sample plots located in the U.B.C. Research Forest at Haney as well as from the forest on the campus of the University of British Columbia, in Vancouver. Modifications in technique for the determination of tree height, crown width and crown closure were developed by the writer and are described in this study. Multiple linear-regression equations were used for the analysis of data. Application of the Electronic Computer Alwac III-E to solve all the multiple linear-regression equations is described briefly. Ease of typing was evaluated subjectively. The present study has indicated: (1) Using a spherical densiometer, a ground estimate of crown closure in per cent resulted in an over-estimate, as compared with the photo-estimate. (2) Tree count could not be used effectively as an independent variable in the construction of the photo-volume equation. (3) Best results were secured when photographs: were taken with a 12-inch focal length and a flying height of 15,600 feet above sea level. (4) For the construction of photo-volume tables, height, crown width and crown closure should be used as independent variables, especially when more than one interpreter is involved. (5) No significant differences were found among photographic papers or finishes used for the determination of photo volume. (6) Photography with a Representative Fraction (RF) of 1:15,840 should be satisfactory for forest typing. (7) The greatest variation was among photo-interpreters. (8) Photo-interpretation could be improved by the standardization of photo-interpretation procedures. / Forestry, Faculty of / Graduate

The intention of this investigation is to investigate the various forms of water wave reflection to a high degree of accuracy. Close range photogrammetry is the technique that is used to measure the water surface profile, as it produces an accurate and comprehensive analysis of the water surface profiles. Conventional photogrammetry techniques (photography) were used in preference to near real time photogrammetry (digital). Although near real time photogrammetry has the advantage of a far higher rate of data acquisition, it does not achieve the same degree of accuracy as can be achieved by conventional photogrammetry, the technique finally used for this investigation. For the generation of the desired wave patterns, certain equipment was developed and modified. To test the various angles of incidence a moveable reflecting wall was built. Due to the small size of the wave basin, an efficient wave absorber was required to absorb the reflected wave generated when oblique wave reflection was investigated. It was observed that a very poor quality wave was being generated by the wave generator, as a result of its flexibility. Consequently the wave generator was stiffened considerably which improved the wave generated. Interesting information was obtained from the analysis of the standing wave. A coefficient of reflection of 1,6 at the reflection wall was obtained, this places new emphasis on the relationship between the standing wave and overtopping. The oblique wave reflection resu1ts corresponded well with theoretical predictions, while no well-defined trends were established for the mach wave. The data for the mace wave did however suggest that previously established trends for the mach wave may not be correct. Close range photogrammetry produced accurate results, and is an excellent method for water surface profile measurement. The results obtained showed that the wave generator was not generating a pure wave, which lead to unknown errors in the results of spot heights. Conventional photogrammetry is a slow process, so not enough data was acquired to adequately analyse the reflection trends. This suggests that in order for the trends to be well-established, near real time photogrammetry should be used once these systems have developed sufficient accuracy.

Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1988 (Endodontics) / Bibliography : leaves 69-75. / Stereoradiographs have been available to dentists since the early 1900s; however, they have never gained widespread acceptance or usage. The complexity of the procedures necessary for taking stereoradiographs has been a deterrent to acceptance of the technique. For this reason a free hand method of taking stereoradiographs has been devised,　during which two exposures of dental radiographs are made, mounted for viewing,　and viewed in the stereoscope. Three evaluators reviewed the stereoradiograph slides and judged them for three-dimensional effect. They found that over 97% of the slides exhibited a three-dimensional result. This free hand stereoradiograph technique may lend itself to generalized acceptance by dentists.