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Modeling Error in Geographic Information SystemsLove, Kimberly R. 09 January 2008 (has links)
Geographic information systems (GISs) are a highly influential tool in today's society, and are used in a growing number of applications, including planning, engineering, land management,and environmental study. As the field of GISs continues to expand, it is very important to observe and account for the error that is unavoidable in computerized maps. Currently, both statistical and non-statistical models are available to do so, although there is very little implementation of these methods.
In this dissertation, I have focused on improving the methods available for analyzing error in GIS vector data. In particular, I am incorporating Bayesian methodology into the currently popular G-band error model through the inclusion of a prior distribution on point locations. This has the advantage of working well with a small number of points, and being able to synthesize information from multiple sources. I have also calculated the boundary of the confidence region explicitly, which has not been done before, and this will aid in the eventual inclusion of these methods in GIS software. Finally, I have included a statistical point deletion algorithm, designed for use in situations where map precision has surpassed map accuracy. It is very similar to the Douglas-Peucker algorithm, and can be used in a general line simplification situation, but has the advantage that it works with the error information that is already known about a map rather than adding unknown error. These contributions will make it more realistic for GIS users to implement techniques for error analysis. / Ph. D.
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Estimation of cortical magnification from positional error in normally sighted and amblyopic subjectsHussain, Z., Svensson, C-M., Besle, J., Webb, B.S., Barrett, Brendan T., McGraw, Paul V. 02 1900 (has links)
Yes / We describe a method for deriving the linear cortical
magnification factor from positional error across the
visual field. We compared magnification obtained from
this method between normally sighted individuals and
amblyopic individuals, who receive atypical visual input
during development. The cortical magnification factor
was derived for each subject from positional error at
32 locations in the visual field, using an established
model of conformal mapping between retinal and
cortical coordinates. Magnification of the normally
sighted group matched estimates from previous
physiological and neuroimaging studies in humans,
confirming the validity of the approach. The estimate
of magnification for the amblyopic group was
significantly lower than the normal group: by 4.4 mm
deg 1 at 18 eccentricity, assuming a constant scaling
factor for both groups. These estimates, if correct,
suggest a role for early visual experience in establishing
retinotopic mapping in cortex. We discuss the
implications of altered cortical magnification for
cortical size, and consider other neural changes that
may account for the amblyopic results.
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Vývoj mapového obrazu města České Budějovice / Development of the cartographic image of České BudějoviceCHARVÁT, Josef January 2011 (has links)
This thesis deals with the historical development of the city České Budějovice and some old maps of Bohemia edited in the period of 1518 - 1847. During data processing of these maps I compare the locations of some chosen South Bohemian cities of one old map with another and with their real location. The next part of the thesis is devoted to the way of displaying the city České Budějovice in each map. Used old maps: Claudian map (1518), Münster maps (1550, 1570), Ortelius map (17th century), Mercator map (17th century), Sadeler map (1620), Aretin map (1665), Vogt map (1712), Müller map (1720), Homman?s heritors map (18th century), Lotter map (1758), Schütz map (1790), Loth map (1847).
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Human optokinetic nystagmus : a stochastic analysisWaddington, Jonathan January 2012 (has links)
Optokinetic nystagmus (OKN) is a fundamental gaze-stabilising response in which eye movements attempt to compensate for the retinal slip caused by self-motion. The OKN response consists of a slow following movement made in the direction of stimulus motion interrupted by fast eye movements that are primarily made in the opposite direction. The timing and amplitude of these slow phases and quick phases are notably variable, but this variability is poorly understood. In this study I performed principal component analysis on OKN parameters in order to investigate how the eigenvectors and eigenvalues of the underlying components contribute to the correlation between OKN parameters over time. I found three categories of principal components that could explain the variance within each cycle of OKN, and only parameters from within a single cycle contributed highly to any given component. Differences found in the correlation matrices of OKN parameters appear to reflect changes in the eigenvalues of components, while eigenvectors remain predominantly similar across participants, and trials. I have developed a linear and stochastic model of OKN based on these results and demonstrated that OKN can be described as a 1st order Markov process, with three sources of noise affecting SP velocity, QP triggering, and QP amplitude. I have used this model to make some important predictions about the optokinetic reflex: the transient response of SP velocity, the existence of signal dependent noise in the system, the target position of QPs, and the threshold at which QPs are generated. Finally, I investigate whether the significant variability within OKN may represent adaptive control of explicit and implicit parameters. iii
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