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GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
GIS and spatial-modelling
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GIS and spatial-modelling

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  • 1. Digital models of the landscape:Geographic Information Systems (GIS) A fragmented world or a smooth world?
  • 2. What is GIS?• GIS-Geographic Information Systems• Computerised information systems designed to handle geo-spatial data – data which relates to location in the world
  • 3. The capabilities of GISGIS gives users powerful capabilities :• to capture and store spatial data in digital formats (data models)• to visualise spatial data and relationships (geographical models)• to ask questions based on that spatial data (data querying and spatial analysis)
  • 4. Prime GIS capability: asking spatial questions• GIS lets us ask questions about the location of things
  • 5. Prime GIS capability: asking spatial questions• GIS lets us ask questions about the location of things – Questions about where things happen Where are there trees of this type?
  • 6. Prime GIS capability: asking spatial questions• GIS lets us ask questions about the location of things – Questions about where things happen – Questions about what happens at a location Where are there trees of this type? What is the GDP of this country?
  • 7. Prime GIS capability: asking spatial questions• GIS lets us ask questions about the location of things – Questions about where things happen – Questions about what happens at a location – Questions about how things are related spatially Where are there trees of this type? What is the GDP of this country? How far across the ocean?
  • 8. Where were there more than 40 FMD cases up to Mar 18, 2001? FMD>40?Questions about where things happen
  • 9. Where were there more than 40 FMD cases up to Mar 18, 2001? FMD>40? Answer in purpleQuestions about where things happen
  • 10. When was FMD first recorded in Gloucestershire?Questions about what happens at a location
  • 11. Which towns are in Gloucestershire?Questions about how things are related spatially
  • 12. GIS capability: visualising spatial data and relationships• Data is stored in structured databases• GIS is used to make spatial data and patterns in data visible• This visualisation can be in the form of maps, charts or reports• These are all models of reality
  • 13. Applications of GIS in Property and Rural Development• Monitoring land use change• Property portfolio management• Land classification• Property value maps• Accessibility mapping• Agricultural monitoring• Environmental impact assessment
  • 14. Land use change Aerial photograph mosaic: 1972
  • 15. Land use change Aerial photograph: 1995 Changed field patterns New woodlandNew roadNew houses
  • 16. Rural Property management
  • 17. Rural Property managementB A
  • 18. Rural Property management B AID farm_name tenure rent_year owner type area 1 Farm A annual lease annual George dairy 467 2 Farm B perpetual lease none George dairy 456 3 Farm C 10 year lease 2006 Henry beef 367 4 Farm D 10 year lease 2003 Thomas arable 678
  • 19. Land classification from Satellite imagesData from Idrisi Project
  • 20. Accessibility mapping rural travel times: before Hurricane Mitch (1998) Source: CIAT - World Bank - UNEP Indicators Project, November 1998. Map source:CITA 1998 Government of Honduras (SETCO) 1998, La Prensa ManaguaTravel Time 1998, La Prensa Graphica San 30 Minutes Salvador 1998 . 1 Hour 2 Hours 4 Hours 8 Hours 16 Hours 2 Days
  • 21. Accessibility mapping rural travel times: after Hurricane Mitch (1998) Source: CIAT - World Bank - UNEP Indicators Project, November 1998. Map source:CITA 1998 Government of Honduras (SETCO) 1998, La Prensa ManaguaTravel Time 1998, La Preensa Graphica San 30 Minutes Salvador 1998 . 1 Hour 2 Hours 4 Hours 8 Hours 16 Hours 2 Days Damaged Bridge
  • 22. Agricultural monitoring Crop “C” area 38 ha Crop “B”area 34 ha Vector farm map laid over raster satellite image Crop “A”area 25 ha
  • 23. Environmental impact assessment
  • 24. Environmental impact assessment Historic site Protected riverAncient forest Environmentally sensitive zones
  • 25. Environmental impact assessment Historic site Protected riverAncient forest Environmentally sensitive zones
  • 26. Building a model: components, principles and rules• All models are built of components• When combined according to set principles and rules they create the model (vector and raster model rules)• The components contain data about reality• That data can be described as discrete or continuous• Discrete and continuous data models show the World in very different ways
  • 27. How computers store spatial data structures• Vector structures are used where real- world objects need to be mapped. – Discrete data models – The fragmented view of the World• Raster structures are used where continuous “fuzzy” data must be mapped – Continuous data models – The smooth model of the World• (Refer back to earlier unit on digital mapping)
  • 28. Discrete data: things with edges - fragments• Vector model• Fragments are things with edges… – A point has an edge of zero length – A line has an extensive edge, with a starting point and end point – A polygon has a closed extensive edge, with no starting point or end point – All discrete spatial data models represent the World with graphic points, lines and polygons – Similar to a paper map...
  • 29. Contrasting a vector models with traditional cartography Paper map: Everything is drawn using points, lines and polygons. But they are just drawings. They have colour, texture, density etc. but no intrinsic information about the real world objects they representDigital vector model: points, lines andpolygons, but each is defined by itsgeographical co-ordinates and is linked todata about the real world object itrepresents. Colour, line thickness etc canall be changed without changing the actualdata intrinsic to the model
  • 30. The vector model as a representation of discrete data Tenancy CropsLand units polygons:Each map has different colouringto represent different sets of datawe want to study. Land cover
  • 31. Examples of discrete spatial data• Political boundaries• Buildings• Land parcels• Roads• Electricity pylons• Rivers (?)• Farm fields (?)
  • 32. But: how discrete are real world entities?Is there an edge here? Whereexactly isthe edge of a forest?
  • 33. Continuous data: things with no edges – smooth surfaces• Raster model• Some things exist wherever you choose to measure them – Every point on the land has a height above sea level – Every place in the atmosphere has an air pressure – Every piece of land has some sort of land cover• These are examples of continuous data and they are difficult (impossible?) to model. The raster data model is one attempt to do this.
  • 34. Continuous data structures: how raster data is displayedWhole region is dividedinto equal sized cellsEach cell holds onevalue (attribute)Attributes can berepresented by colours
  • 35. The raster model as a representation of continuous dataOne cellThe model consists of acomplete matrix of cells, allof the same size, eachwith a single value which isrepresented visually by a Colours show heightramped colour Each cell is assigned one height measurement, which may be the maximum, minimum, median, or mean height of the ground in the cell
  • 36. Raster models aren’t really continuous at all… How the data is visualised as a raster• When we create the raster grid, we are dividing the World into discrete cells and assigning single values to each. There is a hard, discrete boundary around each cell-fragments• Are there any genuinely continuous data models? – They are working on it, warped surfaces and TINs (triangulated irregular networks) are possibilities but they have their own problems.
  • 37. Classifying continuous data: the influence of break points“Continuous” height information
  • 38. Classifying continuous data: the influence of break points“Continuous” height information Classified into 1m bands
  • 39. Classifying continuous data: the influence of break points“Continuous” height information Classified into 1m bands Classified into 5m bands
  • 40. Classifying continuous data: the influence of break points“Continuous” height information Classified into 1m bands Classified into 5m bands Classified into 10m bands
  • 41. Converting vector  raster
  • 42. Converting vector  rasterData can be degraded,unpredictably andirreversibly every time youconvert from one data modelto the other
  • 43. Converting vector  rasterData can be degraded,unpredictably andirreversibly every time youconvert from one data modelto the other
  • 44. What GIS programs are available• Large number of GIS programs on the market – Some are very specialised for scientific purposes – Some are little more than digital map viewers used in asset management• Main systems used: – ArcGIS from ESRI Inc. – Idrisi from Clarke University – Geomedia from Intergraph Inc – MapInfo – Small World
  • 45. RAC GIS systemsArcGIS from ESRIInstalled in room 10

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