21st Century Mapping: An 8 Part Series : Part 1 All Maps Lie
I would like to dedicate a series of posts to writing about Cartography as it exists in the new millennium, with the intention of sharing the incredible technological and cartographic feats of a data driven era, with you, the map consumer. When the idea of cartography or map making comes up, the mind might gravitate towards a 17th century mapmaker with a compass, feather pen, and telescope in hand, frantically tracing the coastline as he sails by, or perhaps you have just assume that google’s satellites have made cartography obsolete. However, the modern day cartographer can be found behind a desktop, working with digital files sent from satellites, drones, or land surveyors. Making a good map requires reliable, current data, which means that maps constantly have to be updated in order to be considered relevant by the scientific community. The process of understanding spatial information is GIS (Geographic Information Systems), which is often confused with GPS (Global Position System). I have come to explain the difference between the two through the analogy
photo : photoshop :: GPS : GIS
A GPS will only tell you where you are while the GIS can tell you how to get from A to B based on the routes that are already programmed, such as streets and highways, and it can be used to analyze everything about a GPS point. The program works with two data types, vectors (point, lines, polygons) or rasters (grids much like photos, where each pixel contains information) which are used to reveal trends, analyze natural systems, and create maps that portray the intended information. GIS works by digitally stacking layers of information on top of each other and using varying layers of transparency to recognize trends and show information in a spatial context. There are also many types of analysis that can also be done with GIS to reveal information about an area, for example, a watershed analysis uses a satellite sourced DEM (Digital Elevation Model) to determine where rainfall will accumulate. Representing complex spatial data, the ability to manipulate many layers of information, and being able to make quick calculations to a significant amount of data are all reasons why GIS has become so popular. However, despite the technological advances in map making, some cartographic conundrums cannot be overcome with the use of a computer.
I would like to make one thing very clear: All maps lie. Maps lie because it is simply impossible to show everything about an area in real time, using 3D modeling, and with completely accurate data, on a scale that is able to show everything in the area. The most basic argument for this fact is that there is a lot of stuff in the world and it is impossible to condense all entities of any place into one 2D representation. This is because the earth is an irregular geodesic (fancy science for generally round but with bumps) and showing a curved place on a 2D surface will require distortion of the real world. In order to represent the 3D world at a manageable 2D scale, we use map projections, which creates a system of representation that limits distortion. The Mercator projection is probably the most commonly known map, which gained popularity because it preserves angles and relative distances, so while Africa is actually 14x larger than Greenland, the calculations you would need to find out how long and which direction you would need to sail is accurate. Below are graphics from Geoawesomness explaining the distortion of some common projections. The Mercator projection preserves size most accurately at the equator, since its main purpose is to maintain the shape of the area, distorted overall area is a way to preserve angles and scale distance.
The Gall-Peters map, however, preserves area, but totally distorts shape and distances. This map is great for actually showing the scalar difference between areas, but it navigational potential falls flat. I have included a graphic below that compares the Gall-Peters (Green) with the Mercator (Black). While both are right in their own ways, each also lies to you in its respective ways.
Another fun projection is the Buckminster Fuller Map, which divides the world into a icositetragon, or in layman’s terms, a 24-sided polygon. This map is great because it can be folded into a 3D shape and it also challenges a common misconception in mapping that North is always ‘up’ however this is not true. Finding a directional grounding is important to remember when looking at digital maps where you can change the scale and direction that is being displayed.
Projections are important, and there are many variations that can be used based on what purpose the map is showing. There is not one best projection, although cartographers will argue about it for the rest of eternity.
The first step of understanding maps is to figure out how the map is lying to you… in other terms, what information is the map distorting in order to show another attribute more clearly. Much like this blog post, which has favored the introductory explanation of map projections to the much more interesting discussion of what mapping in the 21st century looks like. So now that you have made it to the end of this post I will reveal that I too have lied to you, and this specific post will not include information about new-age mapping. However, now that you know the truth about maps, I feel qualified to embark on the 8-part journey with you, sharing what I know and see to be modern cartography.