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GOV1008 MID-TERM REVIEW Introduction to Geographical Information Systems November 13, 2008. General Comment. Look at 2007 MT; exam usually a series of thought questions based on a real GIS application
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GOV1008 MID-TERM REVIEW Introduction to Geographical Information Systems November 13, 2008
General Comment • Look at 2007 MT; exam usually a series of thought questions based on a real GIS application • Exam is usually NOT focused on performing operations but on displaying understanding of the underlying theory • Important to read/review relevant sections in the textbook and be familiar with where to find details on topics covered in course
A Review of Selected Hot Topics
Important Concept - 1 • Vector OR Raster? • Vector: discrete, object view, represents points, lines and areas • Raster: field view, grid with pixels • See Lecture 2 for advantages and disadvantages and examples of each • Measuring Earth: Ellipsoid & Datum • Ellipsoid: model of earth for use in GIS • Datum: glues the ellipsoid used to the geoid shape of the earth, required to maintain constant relationship between the two
Important Concept - 2 • Cartography: factors to consider… • Symbolization • Color use • Map components: scale, north arrow, legend, title, source… • Data Classification • Spatial aggregation • Think Intuitively!
Important Concept - 3 • Measuring Earth: Projections • Definition: the systematic transformation of points on the Earth’s surface to corresponding points on a plane surface • Types: conic, planar, cylindrical; conformal, equal area, azimuthal • Conformal property: shapes of small features are preserved, distortion is the same in all directions • Equal area property: shapes are distorted, but features have the correct area
Important Concept - 4 • GIS Software Architecture • Desktop • Client-server • Centralized: Desktop/Citrix & Server Server GIS Centralized GIS -Deploy multi-user desktop -Internet GIS -Enterprise GIS Servers Manage/deploy centrally, Low cost of ownership, Good for data exploitation
Important Concept - 5 • GIS Database Considerations 1 –User View 2 – Objects and Relationships 3 – Geographic Representation –vector vs. raster has implications for how the database is used 4 – Geographic Database Types – this involves matching the objects to be studied to specific data storage types 5 – Geographic Database Structure – assign a coordinate system to your data 6 – Database Schema – design the actual physical database schema
Important Concept - 6 • Spatial Data Analysis: Transformations • Buffers • Point in polygon • Overlay:Continuous & Discrete • Interpolation: IDW (Inverse Distance Weighted) Kriging, Density Estimation • Spatial Data Analysis: Geoprocessing • Clip, Append, Dissolve, Intersect, Union
Important Concept - 7 • Spatial Analysis • For example: centroid, dispersion, semivariograms, measures of spatial autocorrelation such as Moran‘s I and Local Moran‘s, optimization • ESDA: consider ecological fallacy and the Modifiable Unit Areal Problem (MAUP)!