What are Maps
Today, however, when someone talks of maps, we are driven to think of representations of geographical regions, whether on paper or a digital device. So, one may think of maps of countries, cities, or of various themes. But check out a good encyclopedia, and a whole world of meanings and applications opens up.
Maps are a fundamental concept to an astonishingly wide range of human interests, from of course representing the terrain to studying how the human mind works (the human mind has a similar map of the body, and that is how it gets to know that the pain is coming from the arm). Actually, a map is a fundamental concept, applicable almost anywhere. Any kind of representation can be considered a map; and it need not be visual always. For instance, people working to understand the brain often simulate its working on the computer, by developing what are known as neural networks. Sure there are no neurons in a computer, but the concept successfully simulates them; hence, it "maps" the human brain (or to be perfectly honest, attempts to map).
But for the rest of or discussion, we'll focus on maps in their customary sense - the good old colorful images we find in guides, atlases, applications, and everything else, helping us figure out the world around us.
History of Maps
The curious have always wondered: When was the first time people started to make maps?
While the exact dates and time periods are debated, even our wildest estimates keep getting corrected and pushed back. For instance, it has been commonly believed that the earliest map was the Imago Mundi (world map), believed to have been created in Babylon some 3,000 years ago. However, an article in The Telegraph talked of another surprise discovery: a stone-engraved map in the caves of northern Spain, believed to have been created 14,000 years ago! But looking at it, one would hardly call it a map: just a few lines scribbled here and there on a rather uninteresting rock.
What can it mean, after all? Apparently, its creator wanted to represent the world immediately outside the cave, including water sources, spots where animals could be found, and the like - or so the article reasoned.
Interesting . . . but like we said earlier, since the very definition of a map is hazy, there can't be a unanimous agreement on this.
About Map Terminology
Feeling bogged down by heavyweight terms like Contours, Relief, Projection, True north, and others? Don't worry; just stay with us and we'll make it as easy as the alphabet. Next time, you may forgot how to operate a toaster, but you would always be able to read maps.
(In case you are already much comfortable with the terminology, you may want to skip this section and zoom ahead.)
There is no end to learning cartography and maps. Therefore, it will not be possible to cover everything here, and perhaps not even practical. For most of the users, the terms used by the professionals in the field are of little us. Therefore, we will restrict our discussion to the terminology that is in the common use and will help us get to speed quickly.
Contour lines : Simply put, these are lines that connect places of same height on a map.
Elevation : This is the vertical distance of a point, measured from sea-level. Naturally, a hill station would have a higher elevation than a beach.
Scale : The factor by which an actual area had to be reduced in order for it to be represented on the map. Scaling factors of a few millions are quite common. That is, if you took the map of USA and stretched it a few million times, the borders would overlap perfectly (and you'd have a lot of trouble studying that map!).
Relief : True to its name, a physical representation of the elevation and/or geography on a map, which looks really pleasing to the eye.
Projection : The process of representing the earth's surface on a sheet of paper (or any flat surface). Since the earth is spherical, the resulting map look a bit odd if you seeing something like this for the first time.
Topography : It is a collective term for the various types of features found on a surface. These would include the natural features, as well as the man-made ones.
Magnetic declination : Because of the molten metals at its core, the Earth's magnetic north and south poles do not perfectly align with the geographical north and south. In fact, at some places, their directions are so markedly different that you'll be surprised. Magnetic declination is a measure of this angle, or tilt, that exists between the two north poles (geographic and magnetic).
Among the first cartographers were the likes of Aristotle, Copernicus, Magellan, Polo and Ptolemy... More on Cartography
As described earlier in the section on cartography, Map Design is among the final stages of producing a map. But at the same time, it makes for most of the impact of the overall process. What is map design? Choosing eye-pleasing colors and textures? Yes, that, and much more. While map design is perhaps simpler than rest of the process involved in mapmaking, it is nonetheless challenging in itself.
When all other information has been decided on, we begin with the design of a map. What is meant by this "all other information"? Note that map design is not concerned with the detail in a map; that part is supposed to be handled by the earlier processes. Map design intends to use this detail to create maps that look beautiful.
And this detail comes from a GIS system, which has been explained elsewhere. We will now look at the prerequisites of Map Design, and how the process is carried out in practice.
In order to produce a good map design, there are certain imperative concepts with which one needs to be familiar. Let's look at the quickly.
2.1 Types of maps
This has already been explained, but for the sake of completeness, here's the essence. Broadly, there are two types of maps: reference, and thematic. Reference maps are those that give information about a place, or show the details in some way. For example, a road map, a political map, etc., are examples of reference maps.
On the other hand, thematic maps are used to show the pattern or distribution of something on a map. For instance, world GDP map, climate map, literacy map, etc., are all thematic maps. Of course there is no limit to the type of thematic maps you can create. You can have maps on number of neighbor fights around the world, if you so wish!
You already know what a map scale is. But its implications are important for the map designer. Consider the simple fact that there is only limited area to print the map, and so one is confronted with the choice of scale. You can include more of a map if you keep the scale large, but then you lose much detail.
Which of the information on the map is most useful? Which parts of the map are the most useful? How large is the finished map going to be? Will it be able to focus properly on its goal?
These are some of the important questions a map designer has to ask himself when selecting a scale for the map.
This may sound something trivial, but the scale is actually the most important factor. Choosing a wrong scale will ruin the whole map, no matter how good the printing quality and other processes happen to be.
2.2.1 Understanding Map Scale
Some people have trouble understanding map scale. They think that a map that is drawn on a small scale should naturally have more detail. But if they compare two maps with different scales, it leads to confusion.
The thing to be understood here is the nature of the scaling factor. Scale is nothing more than the zoom-in factor. A smaller scale would mean that we are not zoomed-in that much, and hence we can represent a larger portion of the land on the same area. A larger scale, however, means that we are zoomed in a lot more, which means that only a smaller portion of the land would get drawn on the map. On the plus side, this allows us to plot much more detail in the given area.
Finally, the scale should not be directly understood from the numerical value given in the map. A scale factor of, let's say, 1:300,000 is small scale, and not large scale. This is where the confusion comes in, and should be avoided at all costs.
2.2.3 Selecting a Map Scale
While the map designer is generally free to pick any scale he chooses, the scale of the map must correspond to that of the data available. Yes, the GIS system again comes into play here. Data generated in a GIS system is for a particular map scale, and works best for that case only.
This is not to say that you can't create the map on a different scale. You can, but there will be side-effects: 1) You will lose a good amount of detail on the map; and 2) The map will look weird. The latter part is a natural consequence of not having enough data to plot the terrain.
2.3 Map Projections
Map projections have been explained in a separate section. A map designer must be aware of the final utility of the map, and needs to select a relevant projection. While the Miller projection is the most famous one, we already know that it introduces severe distortion near the poles. Which means that a map designer must be aware of these issues and choose wisely.
3. Map Generalization
When all these things have been figured out, it is time for map generalization. Map generalization is a broad term, and includes many smaller processes. Let us have a look at them one by one. Do bear in mind that the final aim of map generalization is simplification of data and representation, so that a useful map could be created.
4. Selection and Simplification
These twin-processes are used to make the available data set simpler to use. Why would we want to make a data set simpler? And anyway, what does it mean to make the data set simpler?
In a GIS system, there is a great level of detail. The average amount of data stored in a professional map would become impossible to handle if a single person were to try doing that manually. This calls for some modification of the data at hand. Since most of the maps we use in everyday life are not going to be used for surveying purposes, they do not require too much detail. In fact, cramming too much of information into a map can only serve to dissolve its meaning and usefulness.
Need an example of data set simplification? Suppose you have a large database fresh out of a GIS system, which contains location coordinates of all cities in a particular country, along with their population data. Being greedy here will only hurt your map; such vast information is best printed on large wall maps only. So what will you do? You will need to selectively work on the data to tone it down, so to speak. To understand it better, suppose that you finally decide to retain only those cities where the population is more than a million. Suddenly, you have a sleeker, more meaningful (for this particular case) data set that can be plotted on a map.
Achieving such a simplification is not easy. It involves far more than doing a basic filtering, especially because the actual data sets are far complicated.
The process of classification is a natural consequence of the need to handle detail. Again, consider an example to help in understanding the concept. Suppose you are developing a thematic map on the net exports of the world countries. Now suppose you have data on 150 of the countries; how are you going to represent this on the map? Creating 150 shades of a single color, or even 150 different colors is going to defeat the primary purpose: usefulness. When such level of detail is present in a map, it is actually no different from the data set it was constructed from, and so loses its value.
Well, well, we seem to be in a fix! What is the way out? The simple process of classification. We start with grouping together data values that are close to each other, by defining a minimum-maximum range for them. This range is also known as a class, hence the name. Ideally, you can aim for anywhere from 4 to 6 classes, as this is the acceptable number of single-color gradations in a map.
Keep in mind that classification is also quite complicated, given that the data values generated by the GIS system may contain many irregularities.
6. Symbolization Ideally
A map usually has to carry more than one type of information, and if we go on using nothing but colors, it will soon start to look a patchwork. Therefore, certain pieces of information are to be represented by some other means, such as, symbols. You might recall from watching fantasy movies that forests are represented on maps by closely huddled trees. Although that convention would be laughed at today, it gives a good idea about symbols.
Not all symbols need be straightforward to decipher. Most of the maps provide the meaning of the symbols in a small section known as the legend. Since there are usually not more than 4-5 different symbols to be differentiated at a given time, this poses no problems.
A final note of warning before we leave the rather apparently flimsy concept of symbolization: symbols should be chosen wisely, keeping in mind the profile of the end-user, as well as the overall color-theme of the map. At the end of the day, the map designer's job is to make the map useful to the people who are going to use it.
7. Map Composition
When all the previous items have been figured out and the processes defined, it is time for the map designer to enter the final stages and apply himself. Perhaps you are already overwhelmed and asking, "Well, haven't we been doing map composition only all along?!" Well, yes and no. Yes, because certainly map composition does not have a definition cast in stone. No, because that is not what map composition is commonly meant to be in the practice of cartography.
Map composition is closer to the visual design process than any of the foregoing. It is here that the map designer has clarified all the inputs from the previous stages, and having done so, must close his eyes and visualize the final map. This would mean thinking about the various color-themes and font sizes, as well as how the scale is going to be represented. He would strive to achieve the best contrast, and perhaps visual effects like 3D surface.
Also, this stage calls for being very particular about line-spacing, placement of titles, choosing a font-face, etc. Any slight laxity here can spoil the whole map, and so enough caution can never be exercised.
Fuse all these processes together and the map is ready: comprehensive, compact, and beautiful! But be aware that the process of map design was presented in its simplest form here. The idea involved in professional cartography are complex enough for one to start feeling dizzy after the study of a page or two, but we have tried to keep the score straight and help you grasp the basics right.
What next? Why, purchase a book on map design, invest in a good GIS system, and get ready for the harder but more satisfying part of this journey. But if you are like most people, you are happy getting to know the process is more than superficial detail, and leaving the experts to themselves.
Whatever you decide to do, the joys of cartography are many and to be enjoyed by all.
Types of Maps
There are many ways to classify maps, based on their utility, form, or even the technology used. To start with, we will describe the most widespread and natural classification of maps:
Physical MapsAs the name suggests, these maps are used to represent the various physical features of a surface. For instance, looking at the World Physical Map, you can tell where the water bodies are; where the mountain ranges are located; where the various deserts can be found; and so on. This is achieved by color-coding the entire map, which results in something that is quite pleasant to look at, provided the right combination of colors has been used. You can check out the physical maps of the various countries and have a quick overview of their geography.
Political MapsThe maps are more concerned with the regions of governance. On a political map, you can see the various boundaries of cities, countries, etc., as accepted by the countries. However, there are more than enough cases where a particular region is disputed and ends up getting claimed by two or more countries. It is a difficult situation for map-makers, and the best recourse to them is to use a dotted line to show a weak boundary.
Blank MapsThese maps contain only the boundary, and have no other places or features marked. They are great as learning tools, and are used extensively among students. If you keep forgetting the location of world countries or their borders, there is no better way than filling up and cross-checking a blank map. It is also possible for a blank map to have the boundaries marked, so that it can be used for more specific tasks.
Thematic MapsThis is a special case of a map, and is used to display information related to a particular theme. The data is collected from the various geographical regions, and the map is accordingly plotted. For instance, a thematic map could show the various places in the world where diamonds are found and mined, and further classify these regions by color codes. Indeed, the number of thematic maps possible is infinite, to say the least.
Location MapsThe location map is used to mark the location of a particular place with respect to the continent, country or the world. This might seem like an exercise in futility, until you actually see a location map in action. Stripped of all the other details that might be termed irrelevant for the moment, the location map provides an unmistakably clear idea of where the particular place actually lies in relation to other well-known regions. Do this exercise even once and you can never miss the location of a place.
Projection MapsThese maps are used to represent the Earth's surface on plane paper. And herein lies the problem. The Earth is a sphere, while we want to represent this information on a two-dimensional paper. The result is a map that looks skewed and not quite easy on the eye at the first look. However, its usefulness soon overtakes its form, and the map becomes very useful. Globes were made possible in this way only: When that flat sheet is cut and pasted on the globe properly, we get a near-perfect model of the earth. Otherwise, we would have a hard time making sense out of the otherwise perfectly okay map now pasted on a sphere.
We all have got so used to seeing maps all around us that we probably never stop to think about how they must have been made in the first place. Suppose you were given a cuboid-shaped aquarium and told to draw a map of it on a plane sheet of paper, what would you do? The problem is not as simple as it might sound on the first time. The tank in question will have many different types of objects, not to mention fish, and one or more of these will always be in a state of motion. The more you think about it, the more clearly the following question will stand out: "How do you even begin doing it?" The early cartographers were faced with the same dilemma, and answering this question will take us closer to the process of making maps.
What comes to our rescue is a projection. Some of you might even be familiar with it from school days. But while the school was more to do with clearing the exams at all costs, this time we'll aim for learning. If you consult a good dictionary, you will get a bewildering array of definitions on projection, ranging from the obvious to the most surprising. But the word we are looking for is "representation". Representation of what? Of the Earth's surface.
By now you might be beginning to think that we are merely beating about the bush, but wait. Whoever told you Cartography was easy!
Yes, a map projection is a representation of Earth's surface on a plane, such as a sheet of paper. Even though almost all the atlases in the world follow common method of representing the maps, there are in fact many different types of projections.
2. Types of Map Projections
Depending on the underlying logic and methodology, there can be many types of map projections, such as:
Modified azimuthal projection
Then there are tilted and crooked projections, projections from very early days that are no longer existing or useful. Needless to say, the mind reels at even thinking of so many projections. And what if we told you there were as many more . . . ?
But have heart. The good news is that not all of these projections are useful for everyday tasks. Actually, a projection is neither good nor bad. It just is. Every projection has its own use, and commands a lot of respect within its specific application area.
So now we get started on exploring the various types of projections, an learning their particular uses. We'll discuss the most common ones, and those that are interesting. Don't feel overwhelmed just yet. Cartography is interesting, and is to be conquered one step at a time . . .
2.1 Cylindrical Projections
This is the most common of all map projections. Almost all the maps you see around yourself, whether in atlases or elsewhere, were formed from cylindrical projection or some of its variant.
So how is a cylindrical projection achieved? Basically, in a cylindrical projection, the various longitudes are mapped as parallel vertical lines. Yes, we know that definition did not help, but the task will be easier if you imagine the globe to be inside a very long cylinder of exactly the same diameter as the sphere of the globe. All that is now left is plotting the various points on the globe on to the inside curved surface of the cylinder. To achieve this, imagine that there is a point of light inside the globe, which gets obstructed by the continents, but allowed to pass by the water bodies. Such an arrangement would soon illustrate the walls of the cylinder with a particular pattern. And this is the projection we have been looking for! Simple enough it was, no?
Now, if you unwrap this cylinder and spread it out, what do you see? Why, a world map for sure! However, something is not quite right here. Sure enough it is a world map, but it looks weird. If you pay some more attention, you will see that it is not so nicely spaced at the length. This phenomenon is known as "distortion", and is common among the maps produced using cylindrical projections. That is to say, a map produced using this plain-vanilla cylindrical projection is distorted from east to west.
Of course this is not how maps are created. The light sources and un-flattening are merely aid to the imagination. The actual operations are neatly defined by certain mathematical operations, discussing which would be out of scope.
So what did the early cartographers do when they were confronted by this odd-looking world map? Did they just shrug their shoulders and carry on? Not at all. They improvised. The remedy of this map lies in its problem only - distortion. Here's the idea: If the map has a different stretch along the east-west direction, all we need to do is add a similar distortion along the poles. This gives rise to different types of cylindrical projections:
The east-west scale is the same as the north-south scale. This is also known as conformal cylindrical or Mercator projection. One disadvantage of this projection is that the it experiences too much distortion at very high latitudes.
The north-south stretching grows less than the east-west stretching. This is known as Miller cylindrical projection.
The north-south stretching grows faster than the east-west stretching. But this is not a practical projection because the distortion in this case is far worse.
The north-south lines are neither compressed nor stretched.
The north-south distortion is exactly the reciprocal of east-west distortion. This makes for what are known as equal-area cylindrical projections.
The cylindrical projections are good for navigational purposes, especially the Mercator projection, because a straight line drawn on it corresponds to a unique and fixed direction. However, as noted before, the this also results in a lot of distortion at the poles and they can't be shown as a result.
2.2 Conical Projections
We have already seen that the Cylindrical Projections result in significant distortion at the poles. This makes the countries in the higher longitudes a bit difficult to represent, and the poles, impossible. To overcome this difficulty, Conical Projections are used.
How does a conical projection work? This time, the globe can be imagines to be inside a cone than a cylinder. As the different points get projected on the inside of the cone, the lines of latitude get represented by the regular circular arcs, and the meridians get mapped as radial lines that are equally spaced. This gives an accurate representation of the countries closer to the poles, such as Greenland and Canada, and reflects their true shapes more closely.
Another useful concept is that of "standard lines". Standard lines are parallel lines where the sphere touches the cone on the inside. While one of these lines will be point where the two diameters coincide, the other one is set to define the spread of the map. When the map is finally cut open and spread (so to speak), the area of the map will be within these two lines.
Conical projections are not good for creating world maps, but are rather used to create maps of temperate zones.
2.3 Azimuthal Projection
To understand what an Azimuthal Projection is, it is important to first know what an azimuth is. Consider the Earth as a sphere. Now take any point on it. Let us call it point A. From this point, take two points in different directions that are equidistant from it. Now, join both these points to point A. The angle formed between these lines in known as azimuth of the surface.
Now, in an Azimuthal Projection, this angle is preserved. What does it mean? Two things. First, that the azimuth as measured on a map created from the azimuthal projection would be the same as that measured on the sphere. At the same time, it means that the directions are preserved on the final map. This is a great plus actually, as it let us use maps created from these projections to be used for making globes. After all, a globe must accurately represent the Earth.
Depending on the different settings, many types of azimuthal projections are possible. There is only one small problem, though: While such a projection preserves the directions, the shapes can be more than distorted.
2.3.1 Gnomonic Projection
This remains derived from the Azimuthal Projection, and is also known central azimuthal projection. The only difference is that in this type of projection, the light source is imagined to be placed at the exact centre of the sphere, This gives it a surprising about of spread near the edges of the diameter, and doesn't allow the map to represent more than one hemisphere at a time.
But why use this projection at all? As we said earlier, each projection has its own quality, which makes it outshine others in certain cases. The good thing about the Gnomonic Projection is that all the great circles on it (the imaginary planes that cut through the Earth's surface to form the meridians) finally appear as straight lines. This makes it extremely easy to find the shortest distance between two points. The maps do look a bit (or quite) distorted, but that's a small sacrifice when you consider the benefits.
2.4 Other remaining projections
Other projections listed above are merely minor variants of these already listed. For instance, the pseudo-cylindrical and pseudo-conical projections are similar to the cylindrical and conical projections, except that they have curved meridians. A hybrid projection is that which uses many of these projections to produce a map to be used for some specialized purpose.
3. Choosing a Map Projection
Since there is a fair bit of mathematics involved, only the experts can comment on why a particular projection is to be chosen. However, in general, one needs to keep in mind the distortion factor, which is inevitable in any form of projection. Also, one needs to be clear which factor is more important: distances, directions, areas, or the look of the map. For instance, the Robinson projection is a much simpler process that makes the map look very pretty, but can't be used for any other purpose as it has too many deviations from the true representation of the Earth's curved surface. The coordinate origin is another important factor.
Earth is spherical in shape. Any attempt to represent it on a plane paper, however clever, will ultimately fail on one count or the other. Thus, map projections are a good but imperfect representation of the Earth. However, having a good knowledge about the various projections makes you better with using maps, and perhaps, lends you an eye for appreciating the complexity and beauty in the process of map creation.
Last Updated on : Sept, 22 2014