Scale

The actual location size is reduced when representing the Earth on a manageable map. Scale is the ratio between the distance between two locations on a map and the corresponding distance on Earth’s surface. A 1:1000 scale map, for example, would mean that one meter on the map equals 1000 meters, or one kilometer, on Earth’s surface. Scale can sometimes be confusing, so it is important to remember that it refers to a ratio. It does not refer to the size of the map itself but rather how zoomed in or out the map is. A 1:1 scale map of your room would be the same size as yours – plenty of room for considerable detail but hard to fit into a glove compartment.

As with map projections, a map’s “best” scale depends on its use. If you are going on a walking tour of a historic town, a 1:5,000 scale map is commonly used. If you are a geography student looking at a map of the entire world, a 1:50,000,000 scale map would be appropriate. “Large” and “small” scales refer to the ratio, not the size of the landmass on the map. One divided by 5,000 is 0.0002, a larger number than one divided by 50,000,000 (0.00000002). Thus, a 1:5,000 scale map is considered a “large” scale while 1:50,000,000 is considered a “small” scale.

Location

The concept distinguishing geography from other fields is location, which is central to a GIS. Location is simply a position on the surface of the Earth. What is more, everything can be assigned a geographic location. Once we know the location of something, we can put it on a map, for example, with a GIS.

We tend to define and describe locations in nominal or absolute terms. In the case of the former, locations are illustrated and described by name. For example, city names such as New York, Tokyo, or London refer to nominal locations. Toponymy, or the study of place names and their respective history and meanings, is concerned with nominal locations.

Though we associate location with points on the Earth’s surface, locations can also refer to geographic features (e.g., Rocky Mountains) or large areas (e.g., Siberia). The United States Board on Geographic Names maintains geographic naming standards and keeps track of such names through the Geographic Names Information Systems (GNIS). The GNIS database also provides information about which state and county the feature is in and its geographic coordinates.

Contrasting nominal locations are absolute locations that use a reference system to define positions on the Earth’s surface. For instance, defining a location on the Earth’s surface using latitude and longitude is an example of an absolute location. Postal codes and street addresses are other absolute locations that usually follow local logic. Though there is no global standard for street addresses, we can determine the geographic coordinates (i.e., latitude and longitude) of street addresses, zip codes, place names, and other geographic data through geocoding.

Location can also be defined in relative terms. Relative location refers to defining and describing places about other known locations. For instance, Cairo, Egypt, is north of Johannesburg, South Africa; New Zealand is southeast of Australia; and Kabul, Afghanistan, is northwest of Lahore, Pakistan. Unlike nominal or absolute locations that define single points, relative locations provide more information and situate one place concerning another.

Direction

Like location, the concept of direction is central to geography and GIS. Direction refers to the position of something relative to something else, usually along a line. A reference point or benchmark from which direction will be measured must be established to determine direction. One of the most common benchmarks used to determine direction is ourselves. Egocentric direction refers to when we use ourselves as a directional benchmark. Describing something as “to my left,” “behind me,” or “next to me” are examples of egocentric direction.

As the name suggests, landmark direction uses a known landmark or geographic feature as a benchmark to determine direction. Such landmarks may be a busy city intersection, a prominent point of interest like the Colosseum in Rome, or some other feature like a mountain range or river. The critical thing to remember about landmark direction, especially when providing directions, is that the landmark should be well-known.

In geography and GIS, three more standard benchmarks define the directions of true north, magnetic north, and grid north. True North is based on the point at which the axis of the Earth’s rotation intersects the Earth’s surface. In this respect, the North and South Poles are the geographic benchmarks for determining direction. Magnetic North (and south) refers to the point on the Earth’s surface where the Earth’s magnetic fields converge. This is also the point to which magnetic compasses point. Note that magnetic North falls in northern Canada and is not geographically coincident with true North or the North Pole. Grid north refers to the northward direction that the grid lines of latitude and longitude on a map called a graticule point to.

Distance

Complementing the concepts of location and direction is distance. Distance is the degree or amount of separation between locations and can be measured in nominal or absolute terms with various units. For example, we can describe the distances between locations nominally as “large” or “small,” or we can define two or more locations as “near” or “far apart.”

Calculating the distance between two locations on the Earth’s surface can be pretty involving because we are dealing with a three-dimensional object. However, moving from the three-dimensional Earth to two-dimensional maps on paper, computer screens, and mobile devices is not trivial and is discussed in greater detail later.

We also use a variety of units to measure distance. For instance, the distance between London and Singapore can be measured in miles, kilometers, flight time on a jumbo jet, or days on a cargo ship. Whether or not such distances make London and Singapore “near” or “far” from each other is a matter of opinion, experience, and patience. Hence, using absolute distance metrics, such as that derived from the distance formula, provides a standardized method to measure how far or close locations are from each other.

Space

Where distance suggests a measurable quantity regarding how far apart locations are situated, space is a more abstract concept that is more commonly described than measured. For example, space can be described as “empty,” “public,” or “private.”

Within the scope of a GIS, we are interested in space, and we are interested in what fills particular spaces and how and why things are distributed across space. Space is an ambiguous and generic term used to denote the general geographic area of interest.

One kind of space relevant to a GIS is topological space. Topological space concerns the relationships between nature and location connectivity within a given space. What is essential within topological space are (1) how locations are (or are not) related or connected and (2) the rules that govern such geographic relationships.

Transportation maps for subways provide some of the best illustrations of topological spaces. When using maps, we are primarily concerned with how to get from one stop to another along with a transportation network. Specific rules also govern how we can travel along the network (e.g., transferring lines is possible only at a few key stops; we can travel only one direction on a particular line). Such maps may be useless when traveling around a city by car or foot. However, they show the local transportation network and how locations are linked together effectively and efficiently.

Navigation

As previously discussed, transportation maps illustrate how we move through the environments where we live, work, and play. This movement and destination-oriented travel are referred to as navigation. Navigating space is a complex process that blends our various motor skills, technology, mental maps, and awareness of locations, distances, directions, and the space we live in. Our geographical knowledge and spatial understanding are continuously updated as we move from one location.

The acquisition of geographic knowledge is a lifelong endeavor. Though several factors influence the nature of such knowledge, we tend to rely on the three following types of geographic knowledge when navigating through space:

• Landmark knowledge refers to our ability to locate and identify unique points, patterns, or features (e.g., landmarks) in space.
• Route knowledge lets us connect and travel between landmarks by moving through space.
• Survey knowledge enables us to understand where landmarks are concerning each other and take shortcuts.

Each type of geographic knowledge is acquired in stages, one after the other. For instance, when we find ourselves in a new or unfamiliar location, we usually identify a few unique points of interest (e.g., hotel, building, fountain) to orient ourselves. Next, we are building up our landmark knowledge. Using and traveling between these landmarks develops our route knowledge and reinforces our landmark knowledge and overall geographical awareness. Finally, survey knowledge grows once we understand how routes connect landmarks and locations in space. At this point, when we are comfortable with our survey knowledge, we can take shortcuts from one location to another. Though there is no guarantee that a shortcut will be successful, we are at least expanding our local geographic knowledge if we get lost.

Landmark, route, and survey knowledge are the cornerstones of having a sense of direction and framing our geographical learning and awareness. While some would argue that they are born with a good sense of direction, others admit getting lost. The popularity of personal navigation devices and online mapping services speaks to the overwhelming desire to know and situate where we are in the world. Though developing and maintaining a keen sense of direction matters less and less as such devices and services continue to grow and spread, it can also be argued that the more we know about where we are in the world, the more we will want to learn about it.

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