Cartography: Where do All Those Maps Come From?

This post is a submission from Mark Richardson about cartography – making the maps we use to ry to navigate to our friends’ houses and inevitably get lost. Don’t tell Mark I said that.


 

Cartography is broadly defined as the art, science, and ethics of map making and map use. The art of Cartography draws upon the research and practices of graphic design blended with the scientific knowledge of geography. The ethics are about avoiding misrepresentation and creation of falsehoods in the information.

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Some Brief History

The art of Cartography goes back as far as human history. People have always been making maps, of varying accuracy, to try to navigate and understand our place in the world. Early maps were crafted by hand using pens and brushes and did not become widely available until the printing press. The advent of the compass, telescope, sextant and other devices allowed the accurate surveying of land and the creation of accurate sea navigation charts. For a long time cartography was only viewed as a field to map the world; however, as technology and science advanced, people began to use maps to analyze what was happening in the world around us.

The best known and most widely cited first use of analysis in the field of cartography was during 1854 when a Dr. John Snow depicted a Cholera outbreak in London. Dr. Snow mapped out where cases occurred and his study of the distribution led to determining the source of the disease at a contaminated water pump.

Technological Development

Cartography has advanced by leaps and bounds with the creation of computer technology and the founding of Geographic Information Systems (G.I.S.). GIS is a specialized computer system designed to manage, create and analyze geographic information. GIS technology was founded in Canada during the early 1960’s by Dr. Roger Tomlinson who just recently passed away (I met him once at a recent conference; it was weird to meet someone who invented your career).

GIS technology has led to standardized data formats and advanced tools to manage and analyze geographic information. In the modern world GIS is used in a variety of fields such as natural resources, environmental assessments, land surveying, business management (logistics), utility management etc… If you want to learn more about modern GIS systems and/or try some freebie software.

Cartographic Principles

Whether the map maker is using modern computer systems or pen and compass, there are a number of key concepts that must be understood in order to create effective and accurate maps: Projections, Scale, Generalization and Symbolization.

Projections

Whether or not we treat the earth as a sphere or a spheroid, we must transform its three-dimensional surface to create a flat map sheet. This mathematical transformation is commonly referred to as a map projection. The easiest way to understand this concept is to visualize shining a light through the earth onto a surface. Imagine the earth’s surface is clear with the major lines of longitude and latitude (a grid) drawn on it. Wrapping a piece of paper around the earth and placing the light at the centre of the earth would cast shadows of this grid onto the paper. If we then un-wrapped the paper and laid it flat, we would then see that the shape of the transformed grid is different than that on the earth: our map projection has distorted our original grid.
The earth’s spheroid can’t be flattened to a plane any more easily than a piece of orange peel can be flattened – it will rip. When we represent the earth’s surface in two dimensions we can cause distortions in the shape, area, distance and direction of points.
Modern GIS computer systems use mathematical formulas to relate spherical coordinates on the globe to flatten maps. Different projections cause different types of distortions. Map makers take care to use projections that accurately represent the area or activities that are being mapped. One projection may accurately reflect the shape of Canada but poorly reflect the shape of the United States for example. Most regions and countries of the world have developed specific map projections to ensure that local area/distance calculations are more accurate. If you want to see some samples of different Map Projections, click here.

Scale

Map scale refers to the size of the representation on the map as compared to the size of the object on the ground. Scale is usually represented as a representative fraction or proportion for example “1:63,630” “or one inch on the map is to 63,630 inches on the ground (1 Mile)”. Scale in maps is often referred to as either Large or Small scale; this is referring to the size of the representative fraction, ie: a 1:10,000 or 1:50,000 map is considered large scale and small scale maps would be like 1:500,000 or 1:1,000,000.
When making a map it is important to pick a scale that will allow you to display information at a meaningful level of detail without overwhelming the reader. I recently blogged at Length on the topic of scale and fictional worlds.

Generalization

Cartographic generalization is the method whereby information is selected and represented on a map in a way that differs from the real world. Generalizations are made to adapt information to the scale of the map, while not necessarily preserving the precise geographic detail.

If you look at most road maps you’ll notice generalization is very common. If you see a road that is next to a river there is often space provided between the two objects so that you can clearly follow both features where as in the real world the river and road may be directly adjacent to each other. Another example of common generalization is making roads thick enough to place street names within them, it aids the map interpretation but distorts the size of the actual road. Many high quality GIS datasets come in both generalized formats for use on small scale maps and highly accurate (even sub-meter accuracy) formats for use in large scale mapping.

Symbolization

Symbols are the graphic language that a cartographer uses to communicate common elements on a map. Over time symbols and their use have been standardized to varying degrees of success. Symbolization includes the use of colour and annotation to denote features. For example, Colour is commonly broken into blue for hydrographic features, green for vegetation, brown for relief and black/red for human activities. However, depending on the purpose of the map the use of colours can vary wildly, such as on geological surveys.
The use of symbols generally necessitates a legend which is placed on the map to explain any and all symbol elements. For some standards that the United States Geological Survey uses, check here. All of these topics can be expanded upon at much greater length and detail but the above is a good crash course on Cartography and hopefully I’ve piqued your curiosity to learn more on the topic.

About Mark:
My name is Mark Richardson, I’m 36 years old and live in Ottawa, ON, Canada. I’ve been making maps professionally for over 15 years and recently started my own company “Green Hat Designs” to develop my own RPG and to provide my cartographic skills to the field of game design.