1. GI212: Digital CARTOGRAPHY
Lecture 4B – Spatial Arrangement of Geographical Phenomena

2. Outline Introduction Geographical Information
Cartographic representation
Geographical Information System (GIS)
Geographic Dimensions
Map Scale
Map Projection

3. Introduction Types of Maps (review)
There are two general types of maps. Maps that give general information about the location of features are reference maps (E.g. topographic maps)
Those that show the distribution of a specific topic are thematic or statistical maps. A map showing population distribution by country (or province) is a thematic map.

4. Introduction General Mapping Concepts
All maps are representations since features can not be shown in their actual size or even in full detail.
A Map is a model of the earth (or portion of it) at reduced scale.
Because it is not possible to show features at their actual size, they must be generalized.
In addition, 3-dimentional (3D) objects have been flattened for a 2-dimentional (2D) display.
Transferring features from 3D to 2D involves the use of map projection.

5. Introduction
Cont…
Looking at a map, real features like trees or buildings are not seen, rather, the symbols that represent these real features are seen.
In order for the map to communicate its message effectively, theses symbols should be easily understood by the map reader.
Things in the real world are quite different than their map seen on the screen or a page. Is this view of reality still accurate?
Assessing map accuracy is quite difficult. A selective view of reality is shown by all maps, so instead of asking “Is the map accurate?” it is better to ask “Is the map appropriate for my purpose?”

6. Geographical Information
Location – where things are
Proximity – what’s nearby
Patterns – most/least, density
Adjacency – what’s next to
Direction – what’s going/moving where
Overlap – what’s in the same place as
Containment – what’s inside, what’s within
Connectivity – network analysis
Change – time series, change analysis
Others…

7. Geographical Information Visualization
“Geographical information visualization is the combination of geographical information representation and scientific visualization. “ (Yang & Lin, 2008) A Map is the fundamental type of geographical visualization.
The basic theme of geographical visualization is to display geographical features on screen digitally, which can represent all features as a combine layered display.
Graphical representation allow for users to distinguish where geographical features are (location) and their distributed pattern (distribution)

8. Cartographic Representation
Cartographic representation is the topmost level of geographical visualization.
Cartographic representation is a comprehensive capture and display of the distribution, combination and connection of spatial entities (features)
Cartographic representation displays not only the respective quantity and quality characteristics of one geographic feature but the macro (overall) structure of the whole cartographic region.

9. Cartographic Data Model
“A [Digital] cartographic data model is the codification of the geographic features, attributes and processes that produce a desired cartographic product or products through specified software.” (Buckley & Frye, 2015)
This encompasses all geographic features specification and labels with their symbology that will appear on the map.
Cartographic data model is used to save and manage geographical information.

10. Geographical Information Systems (GIS)
Maps were digitized and stored in computers in the 1960s. So in order to process and analyze geographical information, geographical information systems (GIS) were created.
The rapid development of GIS so far, is via the advancement from 2D to 3D and from static to dynamic.
Multiple scales spatial database in GIS base on cartographic generalization principles.
Moreover, the key point for geographic information visualization is the cartographic symbol system.

11. Geographical Information Systems (GIS)
With application requirements rapidly developing, instead of just recording maps in digital forms with computer technology, geographical information system (GIS) becomes a functionality system for geographical information saving, managing, analyzing and representing.
“The target of GIS visualization is to finish cartographic representation for geographical information.”
GIS visualization has three stages according to the quality of mapping, which are graphics, symbolization and cartographic representation.

13. Geographic Dimension Geographic data types
The first step in map making is to determine which type of geographic features are involved i.e. does the phenomena being mapped occur at points, along lines or over areas?
Examples of point features are Airports and Villages while Highways and Foot tracks are of line features. Areal features examples are Provinces and vegetative land-cover (forest area or grassland)

14. Geographic Dimensions
Conceived spatial structure of Map features
Point distributions
Linear networks
Area distributions
Homogenous area
Continuous surface
Also:
Surfaces
Volume

15. Geographic Dimensions
Discrete vs. Continuous phenomena (e.g. People (Population) vs. Temperature)
(0D, 1D, 2D, 2.5D, 3D, 4D)

16. POINT FEATURES Points symbols (zero-dimensional): Locations of points,
with X, Y, Z coordinate
Locations of points, 
Iconic representation,
Size of point symbols

17. LINEAR FEATURES Linear symbols (one-dimensional):
(lines, paths)
Linear phenomena (having length, but no width)
Location: 
from x1, y1, z1, to x2, y2, z2, to x3, y3, z3, ....
Use linear symbols to represent 2D or 3D phenomena

18. AREAL FEATURES Areal Symbols:
(2 Dimensional)
Examples: Lakes, Regions, States/Provinces
Population Density by Census Tracts/administrative boundary
Value by area

19. Surfaces 2 1/2 D Symbols (2.5 dimensional):
a surface in which geographic location is defined by x and y coordinate pairs and the value of the phenomenon is the height above a zero point. 
lack of true Z coordinate (replaced by the attribute values)
Contours and elevation

20. VOLUME TRUE 3D symbols and objects (Three-dimensional):
Any point on the surface is specified by four variables (X, Y, Z, and the values).
3D maps (usually mixed up with 2 1/2 maps)
Underground water quality
CO2 level in the atmosphere

21. Other Dimensions
4D? (Temporal dimensional)
Animation

22. Map Scale
The map scale describe the amount of reduction of Real world objects. This amount of reduction is a certain constant amount.
A map scale is a ratio where one unit on the map represents many times that unit on the ground (i.e. in the real world)
Thus, if a map scale is “1:100”, one inch on the map represents 100 inches in the real world.
The unit of measurement is not important, it can be referred to as one foot on the map represents 100 feet on the ground; the ratio remains constant.
However, it is important not to mix units of measurements
e.g. one inch represents 100 feet.

23. Map Scale Representing Scale
A map scale can be represented graphically or verbally.
Most people find graphic scales easier to use than verbal scales.
For example, 1 inch line labelled 1 mile might be easier to interpret than 1:63,360 which is its equivalent.
Regardless of reducing the map by photocopying or other means of reproduction, a graphic scale remains the same
Suppose you are required to reduce a map by 80% from its original size of a scale of 1inch to a mile (63,360 inches)
A graphic scale will be reduced by the same proportion and will still be accurate when you reduce the map.
A verbal scale will however, have an error of about 25%. One inch on the map will not represent 63,360, instead 79,200 (1.25miles).
Since you cannot control how others use your map, it is better to use a graphical scale

24. Map Scale Describing Scale
Maps are often referred to as “large scale” or “small scale”. A large scale map shows more detail than a small scale, which oddly confuses many people.
If you however, think of scales in terms of fractions this concept will make sense. E.g. 1/10,000 is larger than 1/250,000.
Therefore a of scale 1:10,000 would be larger than a map of scale 1:250,000.
The classification of scales depend on the size of the scales and generally, 1:24,000 and larger is large scale and 1:250,000 and smaller is small scale.

25. Map Scale Describing Scale cont...
A portion of Denver at a scale of approximately 1:24,000
Western Europe at a scale of approximately 1:50,000,000

26. Map Scale Selecting Scale
Describing and representing scale is focused on map display but equally important is the consideration of scale in terms of selecting of data sources which is a pre-component of the mapping process.
Every data set is designed for display at a particular scale or within a range of scale.
Example, representing a 1:100,000 data at its respective scale will look fitting (right) but would look sketchy (incomplete) if represented at 1:10,000.
It will look too crowded (fully occupied) and will take too long to draw, if displayed at 1,000,000,

27. Map Scale Selecting Scale
These two data of north St. Louis showing Missouri River flowing into Mississippi at different scales. Notice that both maps show the same general features but give different impressions. The 1: 2,000,000 scale data has more detailed as this data set contains more information and will take a longer time to display on screen and will also require more storage than the 1:25,000,000 scale

28. Map Scale Selecting Scale
It is advisable to match the scale of your data to your intended map display scale but working with data collected and provided by someone is quite difficult.
Fortunately the availability of multiple scale national level data sets may help with such difficulty.
For example, the UPNG Remote Sensing Center created and manages the PNG Resource Information System (PNGRIS) that captures and provides the national level data for PNG at multiple scales.
These data includes Topographic, climatic, geologic, population, soil and inundation map layers and are produced at a scale of 1:250,000
When displaying multiple data sets, make sure they are scale compatible.
Displaying a small scale data (1:5,000,000) at a large scale (1:5,000) may misinterpret the data as being more precise than what it warrants and will still look incomplete.
This is also because the small scale data will be more generalized on close-up large scale display and features in different layers might not be aligned correctly or may appear unclear

29. At scale 1:10,000,000
Source: PNGRIS

30. Source: PNGRIS
At scale 1:6,000

31. Map Projection
Transforming features from the 3D earth into a 2D display uses a set of rules known as Map Projection.
Many different projections have been developed to suit a particular purpose or region because no flat representation of the earth can be completely accurate
The way map projections handle the following four important properties show how the differ: area, angle, distance and direction.
Preserving all four properties simultaneously is not possible by any one projection though, some combinations such as area and direction can be preserved.
No projection can preserve both area and angles
The map-maker must choose a projection based on the property that is decided to be of significance

32. Map Projection Equal Area Projections
Preserve area and are also called equivalent projections.
Most thematic maps should use an equal area projection
Common projections for the world are Equal Area Cylindrical and Sinusoidal.

33. Map Projection Conformal Projections
Preserve angles, and are useful for navigational charts and weather maps.
Shape is preserved small areas but for large areas such as a continent, the shape will be significantly distorted.
Common conformal projections are Lambert Conformal Conic Projection and Mercator Projection.

34. Map Projection Equidistant Projections
Preserve distances, but no projection can preserve distance from all points all other points.
Instead, distance can be held true from one point to all other points or from several points to all other points.
Several projections have the property of equidistance.

35. Map Projection Azimuthal Projections
Preserve direction from one point to all other points.
This property can be combined with any of the other three.
Thus, it is possible to have an Equal Area Azimuthal Projection, such as Lambert, an Equidistant Azimuthal Projection.

36. Map Projection Compromise Projections
Minimizes overall distortion but preserve none of the four properties.
For example, the Robinson Projection is neither equal area nor conformal, but is aesthetically pleasing and useful for general mapping.

37. End of Lecture
Questions?

38. References:
Amy L. Griffin. (2017), Cartography, visual perception and cognitive psychology from: The Routledge Handbook of Mapping and Cartography Routledge
Accessed on: 12 Mar
Bucley A. and Frye C. (2015), LESSONS LEARNED IN CARTOGRAPHIC DATA MODELING Environmental Systems Research Institute (ESRI), Inc. doi: /
Bryan J. E. and Shearman P. L. (2008), Papua New Guinea Resource Information System Handbook 3rd ed. University of Papua New Guinea Port Moresby.
Environmental Systems Research Institute, Inc. (1996), Introduction to Map Design. Retrieved from: 12/pdfs/intrcart.pdf
Yang M. and Lin L. (2008) A CARTOGRAPHIC DATA MODEL FOR BETTER GEOGRAPHICAL VISUALIZATION BASED ON KNOWLEDGE. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B2. Beijing.