Yearly Archives: 2000

How to make a straight line square

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Revised on: 2011-07-22

Euler’s famous “Königsberg bridge” question, dating back as far as 1736, is often seen as the starting point of modern path finding – was it possible to find a path through the city of Königsberg crossing each of its seven bridges once and only once and then returning to the origin? Euler’s methods formed the basis of what is known as graph theory, and which in turn paved the way for path finding algorithms. Traditionally, network analysis, path finding and route planning have been the domain of graph theory and vector GIS, which is where most algorithms find their application. Contrary to such common wisdom, the research of this thesis for the Msc in GIS explores the topic of network analysis in raster GIS, using MFworks as example software. Current algorithms, procedures and network modelling techniques are investigated and common artefacts are explained.

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Fastest path problems in dynamic transportation networks

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Revised on: 2011-07-22

This research essay and literature review investigates some of the gateways to path finding in static and dynamic networks that are listed in present research literature. A selected set of different approaches are highlighted and set in a broader context, illustrating the various aspects of path finding in static and dynamic networks. It is shown that the A* algorithm is the dominant algorithm for solving fastest path problems. A further attempt is made to draw attention to the advances that have been made in path finding in the field of robotics, in order to establish a lateral relation that can form the basis of further exploration and fruitful merger of the two research fields.

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Book Review: This is where raster GIS started…

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Revised on: 2011-03-08

…well not really, but Geographic Information Systems and Cartographic Modeling by Dana Tomlin sparked the scientific interest in it. The original concepts surrounding surface analysis date back to late 1970s and were championed by Dana Tomlin with his PhD dissertation in 1983, which was later published as this book. In the book, Tomlin introduces map algebra operators based on how a computer algorithm obtains data values for processing raster surfaces. He identifies three fundamental classes: local, focal and zonal functions. Tomlin is a must to any academic student of GIS, since much or nearly all work on raster GIS springs off from Tomlin’s work. The illustrations clearly show that this is an old book, but the knowlegde still remains as brilliant today as it was then. This is a book you want to own, simply because it is very sought after and constantly unavailable from your university library.

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ERDAS tutorial

Revised on: 2011-02-26

About the tutorial

This tutorial is taken from my coursework for the MSc in GIS at the University of Leicester, 1999-2000, and is hopefully of use to other students, including students and researchers not at the University Leicester. It is actually not so much a tutorial, but coursework I did for my MSc in GIS. However,  it is a good example of what you can do with ERDAS.

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