Cartography

Reference map of Australia

Cartography is the process of making maps by displaying a specific geographic area on a surface, usually a flat surface such as paper or a computer screen. Also known as mapmaking, cartography uses visual symbols to represent geographic variables of the area being mapped, such as political boundaries, infrastructure, water features, and geology, depending upon the purpose of the map being produced. Some common types of maps are general reference maps, nautical and aeronautical charts, and thematic maps. The field of cartography is often considered both an art and a science. It requires artistry to ensure that maps are aesthetically pleasing and easy to understand while also using science to ensure that the maps are as accurate as possible.

History of cartography

Cartography has a long history, and its earliest beginnings are rather ambiguous. The earliest attempts at maps are likely found in cave paintings, where game trails and surrounding areas may have been depicted. However, as cave drawings are rarely clear, requiring archaeologists to draw conclusions from sparse and obscure data, debates exist as to whether the drawings are actually maps, or had some other purpose. As civilizations increased, so did the need, prevalence, and clarity of maps. Artifacts from Babylon and Ancient Egypt show some of the earliest undisputed maps.

Grecian cartography

The ancient Greeks were perhaps the first to apply science to the art of cartography. The Greek scholars developed the latitude/longitude grid system, first accepted the idea of a spherical earth, estimated the circumference of the earth with remarkable accuracy, and brought never before seen precision to cartography. Claudius Ptolemaeus, better known as Ptolemy, was a Greek mathematician, astronomer, and geographer who wrote a book containing all his knowledge of geography. This extensive work consisted of 8 volumes and contained all his cartographic and geographic observations, basic principles of cartography, map projection and globe construction, lists of places with their latitude and longitude, valuable information of mathematical geography, and fundamental cartographic principles. Ptolemy’s work would become vital centuries later during the age of exploration and the revival of scientific mapmaking. Much the Greeks’ work in cartography was lost after the fall of the Roman Empire, and little progress was made in cartography during the Middle Ages.

The age of exploration

World map using the Mercator Projection

However, as trade and sea navigation began to increase during the later Middle Ages, nautical charts became increasingly important and advances were made in navigation, especially once the magnetic compass arrived in Europe. During the age of exploration in the 15th and 16th centuries, cartography became increasingly important as a vital part of navigating seas and recording newly discovered lands. Geographic knowledge expanded dramatically and cartographic accuracy, i.e. the accuracy of maps, also increased. During this resurgence of cartographic activity, the printing press was invented, which allowed for greater and more accurate reproduction of the maps created. In 1554, Gerardus Mercator published a map of Europe using what is now known as a Mercator projection. This projection allowed navigators to plot their direction of travel, known as their bearings, with ease. This property made the map projection popular with cartographers for centuries to come.

The rise of scientific cartography (again)

During the 1700s and 1800s, cartography as a science expanded even more. Many of the artistic details, such as sea monsters, animals, and other illustrations that cartographers once placed on maps in areas where they had no data, were replaced with more scientifically accurate and useful information. This period also gave rise to increased surveying and more accurate instruments. Countries began commissioning survey organizations to map their land and coastlines. These projects often began from military needs and required much money and time, so not all countries undertook such endeavors. Western European countries and the United States were the ones who felt it worth the effort. This time period also saw the advent of aerial photography. Although in its infancy, scientists figured out how to take photographs from hot air balloons and military tacticians began to understand its value.

The World Wars and beyond

The eruption of World War I, and then World War II, brought an increased need for even more accurate maps. Armies needed to know what types of terrain they would be facing and where towns were located, pilots needed accurate charts to fly their planes, and navies needed accurate coastal charts more than ever. Aerial photography continued to develop as people began taking photographs from planes and new cartographic technologies were developed. These advancements continued after the World Wars as the Cold War helped sustain the need for accurate maps. The Cold War also encouraged standardized cartographic symbols and map sharing between allied countries (i.e. between NATO countries and between Warsaw Pact countries). The arrival of satellite technology brought with it more remote sensing techniques and the Global Positioning System, also known as GPS. These technologies tremendously increased the accuracy cartographers could achieve as well as broadening the possibilities of what cartographer could do.

The cartographic process

The first step in mapmaking is determining the audience and use for a map. This will help determine the scale of the map, the size of map features and text, which features are most important to show, color schemes of the map, and what projection is used. Knowing this information is important because it will help the map be clear and easy to understand. Once the decisions about scale, important features, color, and projection are made, the cartographer can begin making the map. In modern cartography, most maps are created on computers. Cartographers will find the data they need from online databases, import the data into their mapping software, and manipulate the features to fit the desired specifications.

Types of maps

Three major types of maps exist: general reference maps, thematic maps, and cartometric maps.

• A general reference map shows general geographic information such as roads, rivers, lakes, oceans, political boundaries, mountains, and cities. These maps are used for road maps, political maps, some topographic maps, and anytime someone needs a general all-purpose map.

thematic map of soil moisture in the United States

• Thematic maps portray a specific theme and features related to that theme. Examples of thematic maps include a map of crime in a district, locations where a disease has been contracted, population density, the spread of a species or the range where a species can survive, flood damage, temperature data, and more. Thematic maps are often used to analyze spatial patterns or the result of those analyses.
• Cartometric maps are maps that focus on specific measurements such as area or distance. These maps are used primarily for navigation and are often called charts. Nautical and aeronautical charts are examples of cartometric maps. Nautical charts are used to navigate waterways such as oceans, rivers, and lakes, while aeronautical charts allow airplanes to navigate safely. These maps require exceptionally high accuracy in their distances and measurements so that boats and airplanes can navigate safely.

Cartographic scale

The scale of a map refers to the area that the map is depicting. It is usually denoted by a fraction such as 1:250,000 or 1/150,000,000. These fractions mean that 1 unit of measurement on the map equals 250,000 or 50,000,000 of those same units in the real world. Using fractions to mark scale is helpful because they can be used with any measurement system without having to convert from one system to another (i.e. from feet to meters). In cartography, a map that covers a small area is known as a large scale map while a map that covers a large area is known as a small scale map. This refers to the representative fraction of the map. The fraction 1:250,000 is larger than the fraction 1:50,000,000 just as 1/2 is larger than 1/4 and 1/3 is larger than 1/6. However, an easier way to remember the difference is that the features (buildings, roads, rivers, etc) in a large scale map are larger than the features in a small scale map. It should be noted that while the overall scale of a map has no specific unit of measurement, such as feet, meters, or miles, the scale bar used as a reference bar for map readers does use units such units.

The importance of cartography

Cartography is important because it allows data to be visualized spatially. This can show spatial patterns of population, economic development, urbanization, and much more. Cartography also helps with disaster management and recovery and helps emergency response teams understand what is happening in the area where they are working. Also, with GPS and maps readily available on smartphones, people use maps everyday as they travel, find restaurants, stores, and watch their online purchases as they arrive. Cartography is growing in importance and becoming increasingly embedded in our lives.

See also

Other closely related articles in this wiki include:

Hydrography Geographic Information Systems Map projections

External links

• Maps - from Encyclopedia of Earth
• Maps - from National Geographic Education Encyclopedic Entry
• The Relevance of Cartography - from esri ArcNews article (Winter 2013/2014)
• What is Cartography? - from the Canadian Cartographic Association
• The Cartographic Process - from Penn State University's Department of Geography