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Module 3(symbol) - cartography
Remote Sensing And Geographic Information System Applications (GL 223)
University of Kerala
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Unit 8Unit 8Unit 8Unit 8Unit 8
THE STUDY OF MAP
SYMBOLIZATION
STRUCTURE Overview Learning Objectives 8 Symbolization 8 Symbolization Problem 8.2 Measurement Level 8.2 Feature Dimensionality 8 Visual Variables in Symbolization 8.3 Differentiating Visual Variables 8 Symbols 8.4 Point Symbols 8.4 Line Symbols 8.4 Area Symbols Let us sum up Keywords Answers to check your progress Model Questions OVERVIEW
Every component of a map is a symbol. Map itself is nothing but a symbol. It is a symbol of symbols. Symbols are like words. As the words going same meaning differ from language to language, so also the symbols differ from map to map. Words take the meaning given by its users. Symbols take their meaning give in by the cartographers.
LEARNING OBJECTIVES
After studying this unit, you will be able to
ÿ to study of map symbolization ÿ to Understand the symbols.
The Study of Map Symbolization 105
8 SYMBOLIZATION
A map can represent important geographic characteristic in a far more understandable interesting and efficient way. The process of creating graphic symbols to represent feature attribute values part of what we call symbolization.
Symbolization is critical to any map’s success. Good simplification and classification procedures can be nullified by poor symbolization. Symbols are divided into three types: point, line, area or volume
8 RE SYMBOLIZATION PROBLEM
Symbolization begins with styling or typifying, attribute valves. The symbolization process includes selecting the level of measurement (nominal, ordinal, interval, or ratio) to use in the features visualization. It also includes choosing the dimensionality of the feature (point, line, area or volume). All features exist in a combination of these two aspects. And all features can be mapped in a combination of these two aspects.
Cartographers, must perform two important symbolization tasks before they choose the symbols. They must (1) Select the measurement the dimension for each feature they wish to portray. Making two choices is the essence of the cartographic symbolization problem.
8.2 MEASUREMENT LEVEL
All attribute valves of features existing in reality can be measured on one of the four measurement scales. The four scales of measurement are nested: nominal, ordinal, interval, ratio. In other words when we symbolize date on a map, we can generalize ‘down’ the measurement scale from ratio to interval, ordinal, or nominal, from interval to ordinal or nominal; or from ordinal to nominal But we can’t generalize ‘up’ the scale. We can’t change from nominal to ratio. Most symbols connote only qualitative (nominal) or quantitative (ordinal, interval, ratio) data.
8.2 FEATURE DIMENSIONALITY
Features as having dimensionality ranging from zero to three dimensions. A point feature is dimensionless (zero dimensions). A line feature has one dimension. An area feature has two dimensions and volume has three
The Study of Map Symbolization 107
of using hue for a non-nominally scaled attribute. This use of hue is a poor symbolization choice.
Like hue, orientation is best used to show nominally scaled differences, orientation refers to the angle at which the symbol is placed on the map. Shape is also useful in connoting qualitative, differences in attributes. It is particularly effective when applied to line symbols. For example, shape variations let us define solid, dashed and dotted lines so that they are easily distinguishable on the map. (Fig. 8)
Some of the differentiating variables enhance map orientation is more useful for symbolizing points or areas than for lines. Shape is best used for point or line symbolization and not for areas. Hue is useful for all three.
Secondary visual variables are also three. These variables are created by repeating the basic graphic elements (marks), producing a graphic effect that we call pattern. These secondary visual variables-arrangement (pattern), texture (pattern) and orientation (pattern) were illustrated in see the (Fig. 6).
8 SYMBOLS
Symbols are of three types: (1) point Symbols (2) Line Symbols (3) Area See the (Fig. 6 )
8.4 POINT SYMBOLS
Point symbols are these which give the location of an object or the quantitative value represented by it exactly at the point of its location. Point symbols are of two methods. (1) qualitative and (2) quantitative Qualitative symbols are used
(Fig. 8) Example of Line Symbols
108 Fundamentals of Cartography
top suggest the existence of an object. For example, a dot is put for a town and a cross for a hospital. Such symbols do not represent any quantitative data. The quantitative point symbols can be used to indicate: the presence (2) the length (3) the singe or (4) the volume.
Qualitative Point Symbolization
Differentiating visual variables include shape, have (color) and orientation. All these visual variables are useful in portraying pint data. The visual variables of shape is used to form pictorial symbols. The illustrated differences are measured on a nominal scale. The visual variable of hue would also be a good choice for symbol differentiation. The visual variable of orientation can also be used to differentiate scale attributes of point features. The visual variable of shape to symbolize the same data shown by orientation. (Fig. 8)
Quantitative Point Symbolization
The ordering visual variables include singe, value (color) and chroma (color), the amount y which an object or idea is characterized can be represented either by bars or circles or spheres depending upon the type of data to be represented. Repetition by bars indicates the length or height, by circle or squares, the singe and by cubes or spheres, the volume. In this connection it may be noted that the cubes and spheres are thee dimensional and, hence they take less space than squares and circles. (Fig. 8)
(Fig. 8) Qualitative point symbols
110 Fundamentals of Cartography
Qualitative Area Symbolization
Considering only nominally scaled attribute value, create effective area symbols using the visual variable of shape which creates a pattern when repeated in an areas. Some mimetic area patterns are so standard that they must be used only for the feature. For example, see the standard symbolization for landforms.
Familiar with standardized swamp, desert, and forest symbols.
shown in the cell representing symbols that have a real dimension and represent nominal scale. The secondary visual variables area also useful for nominal differentiation, especially if standardized patterns are available See the (Fig. 6)
Quantitative Area Symbolization
The visual variable of value (color) is effective for symbolizing quantitative conceived of as relating to areas. When value is used in this way a stapped surface or dissymmetric map is created. The visual variable of chroma (color) can also be used to show a real quantitative, but it is effective only on color maps or color monitors, white value (color) is effective on block-and white as well as color maps.
CHECK YOUR PROGRESS
- Every component of a map is a ————
- Simpols are divided into three types: ______________ and
- A line feature has ___________
- An area feature has ______________ and volume has __________
- __________ is one of the most useful variables in cartographic symbolization
- The quantitative point symbols can be used to the indicate——and the _____________ and the ______________.
Module 3(symbol) - cartography
Course: Remote Sensing And Geographic Information System Applications (GL 223)
University: University of Kerala
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