1. Cartographic Abstraction Group 4

2. Contents 1.Introduction 2.Cartographic Abstraction defined 3.Cartographic Generalization 3. 1 Selection 3. 2 Classification 3. 3 Simplification 3. 3. 1 Deletion 3. 3. 2 Smoothing 3. 3. 3 Exaggeration/Typification 3. 3. 4 Aggregation/Combination 3. 3. 5 Enhancement 3. 3. 6 Displacement 4.Symbolization 5.Induction 6.Conclusion

3. 1. Introduction  Maps can be produced through a wide range of online tools and software's.  Maps used in activities such as urban planning, geological exploration and navigation are produced by professional map makers.  The field that deals with mapping is cartography.  Cartography is dealing with the conception, production and study of maps.  Cartography links the environment mapped, map makers, map users and the map itself (Smith, 2014).  The fundamental part of generating a map to depict the environment is a process called map/cartographic abstraction.

4. 2. Cartographic Abstraction  Cartographic abstraction is born of the necessity to communicate.  It is quite impossible to portray everything, even theoretically at a scale of 1:1. Therefore in order to portray the important aspects of reality, various manipulations of the data to be mapped are necessary; these may be grouped into four major categories termed “elements of cartographic abstraction” (Robinson, 1969:52).  The process of transforming reality to a map.  Maps provide an abstract representation of the geographical world.  It is a way to represent entities in a legible manner.  The purpose of having maps created through this is to emphasize certain features and de-emphasize others.

5. Cartographic Abstraction Cont.  Cartographers attempt to portray the essence of a situation in an understandable form.  Each map has a different set of requirements.  Before they begin the process of making the map, data is collected from various sources, e.g. remote sensing and aerial photographs.

6. Figure 1.1: Aerial photo (Source: http://www.usgs.gov/pubprod/aerial.html#aerial) Figure 1.2: Topographic map (Source: http://www.usgs.gov/pubprod/aerial.html#aerial)

7. 3. Cartographic Generalization  The period of generalization began during the 1960s.  This term put emphasis on the shift from a manual to a computer based era (Shea and McMaster, 1989).  Cartographic generalization is the method where information is selected and represented on a map in a way that adapts to the scale of the display medium of the map.  Cartographer is given a license to adjust the content in their maps to create a useful map that shows the relevant geospatial information.  There has to be the right balance between the map’s purpose and the reality of the subject being mapped.  Cartographic generalization processes:  Selection  Simplification  Classification  Symbolization  Induction

8. Cartographic Generalization Cont.  Morrison Model was developed by Joel Morrison in mid-1970s.  Formalized the relationships among four elements of generalization (Simplification, Classification, Symbolization, Induction).  Also known as generalization processes.  C = Subsection of SCR (Sensory elements of the cartographers reality) (Morrison, 1974).  PM = Physical Map. Figure 2: Morrison Model Source: McMaster & Shea, 1992.

9. 3.1 Selection  To process the data, cartographers must go through a selection process regarding the map and the material to be represented.  This is a process of deciding which classes of features will be needed for the purpose of the map.  Morrison (1974) defined selection as the pre-processing step to actual generalization.  No modifications take place (simply to include or not to include major geographical features).  For the best outcome, cartographers must know clearly what information is needed and the purpose of the map.  Scale selection decides:  How much detail you can show  Size of the map  From data collected, decision is made on what to include in map  Cartographers must answer four questions when deciding:  Where?  When?  What?  Why?

10.  Purpose of the map:  Where?  Map of San Diego  When?  Showing current  What?  Traffic patterns  Why?  So that an ambulance can take the fastest route to an emergency. Figure 3: Screenshot of San Diego Real-Time Traffic Application Source: http://www.dot.ca.gov/dist11/d11tmc/sdmap/showmap.php

11. 3.2 Classification  Classification is a standard intellectual process of abstraction that seeks to sort phenomena into classes in order to bring relative order and simplicity out of the complexity of incomprehensible differences or unmanageable magnitudes of information (Robinson, 1969:56).  It is difficult to imagine any intellectual understanding, beyond the very elementary that does not involve classification.  We classify without even thinking about it (E.g. how visual GIS and classification work).  We sort numerical data into averages, above, below average and so on; or condense simple classes such as roads, rivers and so on.  All data can be classified according to several kinds of scaling systems: simply by class called the Nominal, by class rank called ordinal or class with stated numerical limits called intervals.

12. 3.2 Classification Cont.  Classification is concerned with grouping, ordering and scaling features by their attribute types and values (Robinson et al 1995).  This process is essential as it is practically difficult to represent every individual value/attribute on a cartographic image.  There are two methods used to classify maps by:  Qualitative Attributes (Classification according to types)  e.g. Croplands, forest all fall under- Vegetation Table 1: Vegetation class (Source: https://www.google.co.za/search?q=Qualitative+attribute+classification+map&espv=2&biw=1366&bih=623&source=lnms&tbm=isch&sa=X&ved=0ahUKE wiH1oDY94DLAhXFLhoKHVtmBCcQ_AUIBigB#imgrc=W9p883TeMjZgwM%3A)  Quantitative Attributes (Classification according to values)  e.g. grouping according to numbers (1.2.3-10)

13. 3.2 Classification Cont.  Thematic cartography concerns what are called distribution maps, and a large portion of these portray quantitative data.  The majority of these maps must separate data into a given number of classes so as to be able to communicate it by various patterns, tones etc.  The selection of class intervals for use on such maps is a second way that cartography involves a fundamental kind of generalisation.

14. 3.3 Simplification  The process of simplification is the most universal of the four basic elements.  When examined in detail it includes the selection of the characteristics of the particular phenomenon being mapped, the eliminating of unwanted details, and in some instance even the rearrangement, reshaping, or modification of geographical features so as to attain “truthful” representations.  Therefore selective simplification must be practice in order to ensure legibility and truthful portrayed.  When a feature has been selected to be shown on a map, they must undergo the simplification process to accommodate the feature within the available mapping space at a required scale.  Simplification is a technique where shapes of selected features are altered to enhance visibility and to reduce complexity (Morrison,1974).  The larger the scale reduction the greater the effect of simplification thus also increasing complexity.  There are 6 six techniques used to simplify maps.

15. 3.3.1 Deletion  A method where you delete entities to better serve the purpose of the map. Figure 4: Simplification of cities in the western United States by deleting cities with populations below 500,000. (Source: E:\cartographic abstraction presentation\3.1 The Cartographic Process _ Mapping our Changing World.html)

16. 3.3.2 Smoothing  Eliminating unnecessary geometric elements on map attributes/features. For example detail on a nation’s shoreline, which can only be seen at a larger zoomed in scale.  The amount of information that can be shown per unit area decreases in geometrical possession. Figure 5: Extracted instantaneous shorelines (Source: Goncalves et al. 2015).

17. 3.3.3 Exaggeration/Typification  Typification portrays the most typical component of a mapped feature, might be cartacious and depicts only key aspects of each states shape.  Deliberate exaggeration of map features is frequently performed in order to allow certain features to be seen.  It is almost impossible to show roads, buildings and small streams at a larger scale (1:2500) without prominently enlarging them (Robinson et al. 1995).  At smaller scale it is significant to enlarge them, and to be able to depict their distinct its geographic character.

18. 3.3.4 Aggregation/ Combination  Aggregation combines multiple features into one. For example various small meandering streams when zoomed out depicts a large river (Robinson, 1978).  Grouping and combining features of the same type.

19. 3.3.5 Enhancement  Almost all simplification methods place significance of detail omission or reduction, enhancement concentrates on the addition of details, used to portray the true character of an attribute/entity.  Highlight a specific detail according to the cartographer’s knowledge e.g. meandering stream  Enhancement is a valuable tool in aiding map reader to components that carry weight on the maps intent (Al-Ghambi 1998). Figure 6: Properties of a meandering stream (Source: https://www.google.co.za/search?q=river+rapids+maps&biw=1366&bih=623&source=lnms&tbm=isch&sa=X&ved=0ahUKEwivgKan8I DLAhWDMhoKHe70DLwQ_AUICCgC#tbm=isch&q=meandering+stream&imgrc=aDwJzGY3Z9xhGM%3A)

20. 3.3.6 Displacement  Displacement is employed when two objects are so close to each other that they overlap at a smaller scale.  Displacement is often a resultant of exaggeration. Figure 7: Kinshasa and Brazzaville on either side of the Congo River. They are both the capital of their country and on overview maps will be demonstrated with a slightly larger symbol than other cities. (Source: www.shutterstock.com)

21. 4. Symbolization  Symbolization is the process of graphically coding the information and placing it to a map (Robinson, 1995).  It is when cartographers use graphic marks to encode the information for visualization.  Symbolization is one of variety factors that can easy influence the effectiveness of the map.  In symbolization, legends are also included; which is the key that explains every symbol that is represented on a map (Robinson, 1995).  Cartographers use different symbols on maps to represent real spatial features.  Three common types of symbols:  Point  Lines  area symbols

22. 4. Symbolization Cont.  In static features, cartographers use point symbol to show exactly where something is located on the map (schools, tree, hospital)  Continuous features, such as river, power lines, roads and boundaries cartographers use line symbols to represent those features.  To represent features such as a residential area, lake or forest on map, the area symbol is used.  Symbols can also be geometric, mimetic or pictorial.  Geometric symbols are simple shapes such as squares, circles and triangles.  Mimetic symbols are often created as a combination of geometric shapes such as a square with a triangle on top to represent a house, or they can be more complex, like a small cartoon of a particular type of building like a ranger stationer or a museum. Figure 8: Geometric, Mimetic, Pictographic symbols

23. 4. Symbolization Cont.  Colour: Usually, we designate the rivers in blue, the vegetation in green, contour lines in brown, roads in black and boundaries -red  Shape: the simple geometrical forms as a circle, a square, a rectangle a rhomb etc. have its own symbolic. Figure 9: Point, Line, Area Symbol Source: Stanislav, 2006.

24. 5. Induction  Induction is the term cartographers use to describe the process where more information is presented on a map than is supplied by original data.  Induction is when cartographers make inferences from interrelationships among features on the map.  Cartographers have little control over induction.  When cartographers apply induction, they extend the information of the map beyond features.  It when cartographers add more information about the feature, but not presented on map.

25. 5. Induction Cont.  A good example of induction by Robinson (1995). Suppose you have January average temperature for a series of weather station.  One can also do that by Suitable logical contouring (isolated data points) construct a set of isotherms.  Isotherms allow inferences about the probable January temperature in areas between a weather station location.  They convey more information than temperature recorded at weather stations.  Any logical extinction of data found on accepted association is inductive.  Induction can be encouraged by a good clean cartographic design after classification, simplification exaggeration and symbolization.

26. 6. Conclusion  Creating a map is time consuming and is not just one step.  Cartographic abstraction is simply transforming reality into map.  Cartographic generalization is the processes that take place in order to transform reality into a map.  Simplification, Classification, Symbolization and Induction.  Before making a map, cartographers must know the purpose of the map for best outcome.  A number of manipulations take place to produce the physical map from data collected in order to represent the purpose of the map.

27. References  Al-Ghambi, A.A. 1998. Cartographic Line Simplification. A Formal role within digital cartographic production. Department off Geography. Leicester.  Goncalves, G., Duro. N., Sousa. E., & Figueiredo. 2015. Automatic Extraction of tide- coordinated Shoreline using open source software and Landsat Imagery. University of Coimbra. Portugal.  Morrison, J.L. 1974. A theoretic framework for cartographic generalisation with emphasis on the process of simplification. International Yearbook of Cartography. 13:59-67.  Morrison, J. L. 1974. A Theoretical Framework for Cartographic Generalization With Emphasis on the Process of Symbolization. International Yearbook of Cartography, p. 123.  Robinson, A.H, Sale. R, & Morrison. J.L. 1978. Elements of Cartography. 4th Edition. John wiley and Sons. New York.  Robinson, A. Morris.J. Muehcke, P., Kimaling A., and Guptill, S. 1995. Elements of Cartography. 6th Edition. John Wiley and Sons. New York.  Stevens, J., Smith, J. M., Bianchetti, R. A. 2012. Mapping Our Changing World. Department of Geography, The Pennsylvania State University.