EG1106 Geographic Information: a primer Mark Cresswell: Room E449b

1. EG1106Geographic Information: a primerMark Cresswell: Room E449b 15th October 2004 Maps & Representation

2. TOPICS What is a map?How do maps provide information?Map Abstraction and GeneralisationUsing maps to communicateGISPractical Today and IN TWO WEEKS

3. What is a map? Maps convey information about a place by graphical (or tactile) meansUse of lines, points, symbols, shading and contours convey essential elements about a place.Every map has a spatial frame of reference - such as gridlines (Ordnance Survey for example), geographical co-ordinates (latitude & longitude) or more localised (postcode or political wards)Maps rely on a simplification of reality

4. What is a map? Is this a map?

5. Western and Central Europe Eastern Europe North America Asia Central America Africa Australia and New Zealand South America What is a map? Is this a map?

6. What is a map? Is this a map? Do all maps have to faithfully replicate even gross features of reality - or can they be exploited to communicate concepts?

7. What is a map? The map of the London Underground was originally drawn in the 1920s by Beck who was an electronics draughtsman The Tube map is easily understood by everyone who uses it - but it bears little relation to the “real” railway network layout.

8. How do maps provide information? Scale and Representation All conventional maps have a SCALE - this tells the user how the features on the map relate spatially to the world it depicts. Without a scale, maps do not inform the user of key information such as DISTANCE and SIZE.

9. How do maps provide information? Consider the usefulness of this map A B D N C

10. How do maps provide information? Consider the usefulness of this map A B D N C 100 miles

11. How do maps provide information? Symbols and colours

12. Map Abstraction and Generalisation All maps show a simplification of realityComplex real-world features are deconstructed and projected onto a 2-dimensional spatial reference systemMajor features become a collection of lines, points, polygons and symbolsCartographers will take an aerial photograph and produce a map retaining the essential elements - but without the complexity and unimportant information

13. Map Abstraction and Generalisation GENERALISATION - varies the quantity of detail according to the scale.A map at a scale of 1:100 000 will have only a quarter of the space available for portraying information about a region than a map at a scale of 1:25 000

14. Map Abstraction and Generalisation ABSTRACTION - This is the process whereby complex features such as drainage channels, road networks and buildings are reduced to:Linesthe thickness of which may not be related to realitySymbolsa church or hospital will have a standard symbol regardless of the size of the hospital or religious denomination of the church

15. Using Maps to Communicate A map does not have to be a road atlas or A to Z format of publicationMaps can be used to display any data that has a spatial (geographic) component.We can show a map of a region or country and graphically show data in the form of colours and/or symbol size. These are CHLOROPLETH maps.

16. Using Maps to Communicate

17. Using Maps to Communicate

18. Using Maps to Communicate

19. GIS Geographical Information System Based around computer software Maps become DYNAMIC – they can be updated as often as the information changes Maps can be carried on digital devices – handheld computers with high resolution screens – updateable in real-time.

20. GIS

21. PRACTICAL TODAY Groups D1, D2, E1 & E2 2 – 3:30 pm In room L106 (Loxford)

22. PRACTICAL IN 2 WEEKS (29th Oct) Groups A2, B1 and B2 2 – 3:30 pm Groups A1, C1 and C2 3:30 – 5 pm In room L106 (Loxford)