1. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl Maps give us a wider view than we can normally see by shrinking a larger portion of the earth down to a smaller size so that we can see it all at once. Map scale

2. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl We know the exact relationship between the real-world sizes of things and their sizes as shown on the map. The relationship is a ratio. map size : real size

3. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl map size : real size 1 : ? 1 : 50 000 1 50 000 Scale is expressed as

4. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl A large scale map makes features larger but can show a limited area. It can carry more detail because there is usually more space for the features. A very large scale map may be called a plan. A small scale map represents a greater area of the earth but carries little detail. Regional, national, and international extents are typically shown on small-scale maps. Large and small scale maps

5. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl Bar scale: a line on a map subdivided into map units which are equivalent to ground distances and labelled with the ground distances. The ground distances must be round numbers. Example: Scale is 1:63,360 How do we calculate intervals for a bar scale?

6. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl Example:Scale is 1:63,360 Therefore - 1 cm (map distance) = 63,360 cm (ground distance) = 633.6 m x cm = 1000 m then x:1 = 1000:633.6 and x = 1.58 cm 04000 m 1.58 cm

7. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl 1:10 000 1:5 000 000 which is the smaller scale?

8. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl Cartographic Generalization No matter what the scale of the map, there is never enough space to show all available detail in all its complexity. The process of selecting detail and simplifying features is called cartographic generalization.

9. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl Types of cartographic generalization: 1. selection 2. simplification 3. classification a. general categories b. which features a. smoothing (linear features) b. combination (areal features)

10. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl Figure 2.2 in Heywood et al. Generalization through change of scale

11. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl

12. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl combination through change of scale this is an example of qualitative data classification

13. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl Geological map of Utah, 1879 (David Rumsey Collection)

14. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl 1:250,000 1:500,000 photomechanical reduction

15. GEOG 2007A An Introduction to Geographic Information SystemsFall, 2004 C. Earl 1:25000 1:50000 new compilation