Gis Concepts 5/5

Concepts and Functions of Geographic Information Systems (5/5) MSc GIS - Alexander Mogollon Diaz Department of Agronomy 2009

Concepts and Functions of GIS .PPT Topic #1 Topic #2 Topic #3 1 A GIS is an information system GIS is a technology 2 Spatial Data modelling Sources of data for geodatasets Metadata 3 Geo-referencing Coordinate transformations 4 Database management 5 Spatial Analysis

Functionalities of GIS INPUT QUERY - DISPLAY - MAP ANALYSE STRUCTURE MANAGE TRANSFORM

Spatial analysis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Spatial analysis & Topology ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Topological properties of vectorial geodatasets ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Raster topology Column-/row-number of cells implicitly contains topological information

Spatial (topological) analysis for vectorial objects ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

1. Generalisation ,[object Object],[object Object],[object Object],[object Object]

1. Generalisation of lines; of polygons

A A DISSOLVE polygons = dropping boundary lines using topological info

Aggregation - Vector ,[object Object],[object Object]

2. Overlay of geodatasets ,[object Object],[object Object],[object Object]

Topological Overlay Poly-on-Poly

Topological overlay line-node, poly-line, left-right is modified

Topological overlay and Boolean logic Intersection Union Subtraction Union without intersection Applied to overlapping polygons and/or lines

Topological Overlay Line-in-Poly

Topological Overlay Point (node)-in-Poly Half-line algorithm: At uneven # intersections, Point is in last-left polygon

3. Proximity analysis (= Buffering) ,[object Object],[object Object],[object Object],[object Object],[object Object]

3(C). Operations on the bufferzone ,[object Object],[object Object],[object Object],[object Object],[object Object]

4. Multi-criteria location analysis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

5. Network analysis ,[object Object],[object Object]

Spatial analysis of raster-geodatasets ,[object Object],[object Object],[object Object],[object Object],[object Object]

Distances in raster-geodatasets

1. Buffering - Raster TARGET = cell or group of cells BUFFERING = selection of cells which match the distance threshold. Result = WINDOW Operations can be performed on the window, e.g. FILTERING

2. Example: Majority filter 5 * 5 The most frequent class in each (moving, e.g. 5*5) window is atributed to the central cell

[object Object],[object Object],[object Object],2. Example: Convolution-filtering

3. Map Algebra ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

4. Cost-Distance analysis using a ‘friction’ surface or friction-geodataset Friction surface

4. Cost-Distance analysis (1/v in min/km) (min; resolution = 1 km)

Summary of important items ,[object Object],[object Object],[object Object],[object Object]

Questions or remarks ? Thank you …

Gis Concepts 5/5

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Gis Concepts 5/5