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Windholz Thomas

How to Handle Accuracy in Hybrid GIS


This thesis elaborates on the possibilities for a combination of different error while focusing on different GIS map representations. The overlay operation of a raster- and a vector-based GIS in a hybrid system requires the application of a common accuracy Measure. In the first part of the thesis different Measures and their Metrics for the Primary Parameters (positional, thematic, temporal accuracy, completeness, and logical consistency) are discussed. In the remainder of the thesis only thematic accuracy is taken into account when dealing with the representation of the inherent inaccuracy. This thesis suggests the approach to transform the accuracy of the stored representations into probability areas. For each of the representations (i.e., raster- and vector-based GIS representations) an error model is given that allows to generate these probability areas. For a raster representation the model of categorical data is discussed. For a vector representation a model where the vertices are considered to be stochastic variables is used to handle the inherent accuracy. Ways of including or neglecting the existing correlation between the vertices are given. Furthermore, the qualities of the mathematical model kriging are investigated in order to generate the required data for the raster model. Finally, possibilities for the combination of both models are discussed.

web address: http://www.spatial.maine.edu/~twindhol/

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