Map Outputs
Cartography may be defined as the art and science of map making and is somewhat broader in scope than map making. Cartography has evolved over time with the advancement of technology. In the past, maps were mainly produced by hand whereas today, maps are produced with the aid of computer programs and GIS software packages, such as ArcGIS.
Types of Maps
There are three main categories of maps: reference maps, thematic maps, and mental or cognitive maps.1. Reference maps (general purpose maps)
These maps show natural and human-made features of general interest for public use. Reference maps emphasize location, and their purpose is to show features (e.g., coastlines, political boundaries, roads, cities, etc.) on the Earth’s surface or a portion thereof. Examples of reference maps include topographic maps and maps of countries and provinces.2. Thematic maps (special purpose maps)
These maps depict a theme about a particular subject and involve the mapping of physical and/or human phenomena. A key characteristic of thematic maps is that a single theme is chosen for the map; this is what distinguishes thematic maps from other map types. Thematic maps may be further sub-divided into two groups: qualitative and quantitative maps.- Qualitative thematic maps: Depict the spatial distribution of nominal or categorical data (e.g., ecoregions, geology, land-use/land-cover).
- Quantitative thematic maps: Depict the spatial distribution of numerical or quantitative data (e.g., annual household income, population density). In most instances, a single variable (e.g., population density) is chosen and the map focuses on the spatial variation of that feature.
3. Mental (or cognitive) maps
These maps consist of mental images that have spatial or geographic attributes. Mental maps are developed in our brains over time, based on our knowledge of particular area and other sensory inputs.Map Scale
Map scale is a ratio of map distance to Earth distance (Dent et al., 2009, p. 11). The scale that is used on any map is dependent on the purpose of the map as well as its size. The selection of scale for a map is perhaps the most important decision that is made during the mapping process as the scale may ultimately determine what is included (and excluded) from the final map product.Large scale maps show small portions of the Earth’s surface in great detail. For example, a map of the Niagara Region would be an example of a large scale map. Small scale maps show large portions of the Earth’s surface in limited detail. For example, a map of Canada would be an example of a small scale map.
There are three ways in which scale may be expressed on a map: representative fraction, verbal scale and bar scale.
1. Representative fraction: This is the ratio of map distance to the distance on the Earth’s surface.
- For example: 1:50,000 - 1 unit on the map represents 50,000 of the same units on the Earth’s surface.
- E.g., 1 cm on the map represents 50,000 cm on the Earth’s surface
2. Verbal scale: This scale “reads like a spoken description of the relationship between map distance and Earth distance” (Slocum et al., 2009, pg. 199).
- For example: “1 cm represents 1 kilometre”
3. Bar scale: This scale resembles a ruler on the map that can be used by the map user to measure and determine distances on a map.
The Mapping Process
There are three main components of the mapping process: reduction, generalization, and projection.1. Reduction: involves scaling down the real-world to map size
2. Generalization: This is guided by the map’s purpose and consists of four steps.
- Selection: This involves early decisions in the map making process such as what geographic space will be mapped, what is being mapped (i.e., features, data, etc.), projection to be used, and other decisions.
- Classification: Objects are placed into groups based on similarity. This reduces complexity and helps to organize the information presented on the map, which in turn enhances communication.
- Simplification: Both selection and classification are examples of simplification. Simplification involves reducing the number of points that make up a line. A good example of simplification would be taking a complicated coastline (e.g., Newfoundland) and making it more simplistic and generalized.
- Symbolization: Representing the data by graphical symbols. There are two major classes of symbols: replicative and abstract.
- Replicative: symbol looks like its real-world counterpart. For example, an airport is represented by an airplane; a hospital represented by the letter “H”.
- Abstract: symbol does not look like its real-world counterpart and requires a legend to explain the meaning. Examples may include geometric shapes such as circles and squares. These shapes are traditionally used to represent amounts that vary from place to place, but can represent anything.
3. Projection: involves the transformation of the spherical earth (3D) onto a flat (2D) surface.
Cartographic Communication
Communication between the map maker and the map user is of the utmost importance; after all, if the map reader is unable to understand and extract meaningful information from the map, then the map maker has not done his or her job effectively.To ensure effective communication between the map maker and map user, an understanding of the principles of map design is important. Effective map design requires the map maker to understand how the map will be used.
Cartographic Design
The purpose and role of the map is to communicate spatial information to the user. The job of the map maker then is to determine the most appropriate and effective means for communicating this spatial information. Key components of map design include:- The frame of reference
- Includes map elements such as the scale bar, north arrow, inset map
- The projection
- How much reduction needs to occur?
- What projection should be used based on the area being mapped and the map's topic?
- The features to be mapped
- What information should be included and what information is left out?
- The level of generalization
- This is determined by the scale of the map.
- Annotations used
- This includes items such as labels, map title, and other text that may appear on the map
- Symbolism used
- Colour scheme, choice of symbols, etc.
Goals of Map Design
There are seven main goals of map design including clarity/legibility, order, balance, visual contrast, unity, harmony, and visual hierarchy.1. Clarity/Legibility
Maps should only include the information that is necessary to convey the map’s message. Presentation should be clear and the map should be aesthetically and functionally pleasing. Objects should not be too small that they cannot be seen or understood by the map reader.
2. Order
Order refers to the logic of the map. There should be no clutter or “map noise” on the map. It is important to understand that some map readers may not look at the title first.
3. Balance
Balance refers to the organization and layout of the map elements. Is there empty space on the map? Does the map have a visual balance? The visual centre is just above the actual centre of the map. Heavy objects should appear on the right hand side of the map (given that the eye tends to read from the upper left to the lower right).
Nothing on the map is too large or too small; too thick or too thin; too dark or too light; too close to the edge or too long/short.
4. Visual Contrast
Visual contrast refers to visual differences between mapped features that permit distinction. For example, the use of thin and thick lines and the use of colour.
5. Unity
Unity refers to the inter-relationships between map elements. For example, font style is consistent throughout the map and no more than two font styles are used. Labels are presented in a consistent format. For example, all labels are in upper case.
6. Harmony
There are no clashing elements on the map.
7. Visual Hierarchy
Visual hierarchy refers to the graphical representation of intellectual hierarchy. Each element is important; however, the subject of the map is the most important.
