Cartography

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2 Cartography.

Abstraction and signageAll maps are the result of abstraction and the use of signage to represent phenomena.

See also: Dynamic visual variables | Literal comparisons | Pictograms

| Varying symbols

Whereas the principal task of map design

is in the decisions taken to select, omit,

and symbolise phenomena, there are

many processes at work that are difficult

to accommodate. For instance, induction

occurs when the mapmaker builds signage

that depends on some level of inference

between mapped features. In this sense,

they are applying inductive generalisation to

extend the map’s content without physically

adding more symbols. The use of contour

lines is a good example of the process of

induction since, depending on the distance

between contour lines and whether they

get progressively closer or more distant,

inference is made about the nature of the

landscape. A concave ridge will be flatter

toward the summit and steeper toward its

base. Contours will be closer together at

the base and further apart at the summit to

represent and infer this.

Although certain inferences might be

imbued into the map by the mapmaker, the

map reader will inevitably play a role in

interpretation. Someone with a good sense

of map use and reading might find it easy to

see and understand such inferences but, for

others, the inferences may be harder to see.

For this reason it is best to avoid inductive

generalisation where possible and, instead,

solve your communication dilemmas through

good, clean design with more obvious visual

cues.

Because the world around us is a complex one, it would be

virtually impossible to simply place a small version of it on

a map. There would not be the space to adequately represent

all features that exist in the mapped area even in a reduced

form. Consequently, all maps are abstractions of reality and

are used to display a selection of objects and attributes. All

maps are inherently a reduction of reality and so the amount

of information you can put on a map will be a reduced form

of that reality. This means a map will omit information to a

greater or lesser extent depending on scale and purpose.

But more than reduction (through selective omission), the

features that are mapped are subject to a range of additional

processes, such as classification and simplification, that

make it easier to understand the true spatial patterns and

relationships that exist in reality.

The way in which we represent features and their attributes

is through the design and placement of graphical signs.

These signs do not necessarily take on the appearance of the

object in reality but are used to represent the object. The signs

should have meaning to enable the map reader to interpret

them accurately and appropriately relate them to the real-

world object. We refer to the process of encoding meaning

into the map as symbolisation. At its simplest level, part of

the job of the mapmaker is to design and place symbols that

reflect either location or some characteristic of the data. There

is considerable scope in the design of symbols and every

mark on a map can be considered a symbol in one form or

another, from those that represent points, lines, and areas to

the typographic components and the marginalia or contextual

information.

Clarity and purpose follow from a careful consideration

of abstraction and signage. Beyond the science of choosing

and representing the information, the sophistication of the

intended audience, scale, and conditions of use must also be

considered so you end up with a clear and concise map that

your map reader can easily translate into meaning.

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3Abstraction and signage

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4 Cartography.

Additive and subtractive colourMapping for screen or print demands a different approach to colour specification.

See also: Elements of colour | Mixing colours | Printing fundamentals

| Transparency

Colour is seen through the stimulation of

different cones in our eyeballs. For three

beams of overlapping red, green, and

blue light, all three types of cones are

stimulated simultaneously and this creates

the perception of white light. Where only

two beams overlap, the transmitted light

produces a mix of colour that is formed by

the stimulation of pairs of cones. Blue and

green together form cyan, blue and red form

magenta, and red and green produce yellow.

By altering the intensity of each of the beams

of light, different colours can be created.

On maps, thin linework in colours other

than black is often required. For instance,

pale blue for rivers and brown contour

lines are not easily created. Brown lines

can be created by overprinting pale tints

of all three process colours. However,

registering thin lines on top of each other is

often beyond technical limits of the printing

process, leading to lines that are blurred.

Furthermore, each line is composed of small

dots of each of the process colours so this in

itself renders a line that can never be sharp.

Because of these problems, printers can

premix inks for certain colours. Premixed

colours are called spot colours and, in

fact, most national mapping agencies print

topographic maps using spot colours or a mix

of four-colour and a few spot colours. Spot

colours can also be printed in percentage

tints so open water can be a percentage tint

of a blue spot colour.

Printing ink manufacturers produce a range

of spot colours. One such system, Pantone,

produce spot colours by mixing two or three

of a basic set of nine colours plus pure black

or white in predetermined proportions.

Pantone provide a worldwide standard for

colour specification, and if a map is sent

for printing with a colour specification that

identifies a particular colour as a Pantone

colour, the printer will be able to match it.

Map colours are specified by mixing additive or

subtractive colours. For screens, additive colours red, green,

and blue (RGB) are mixed. For print, subtractive colours of

cyan, magenta, and yellow (CMY) are mixed. These two

systems are not perfectly interchangeable since purity of light

is not matched by printing ink. For instance, you cannot mix

the very vivid colours made possible on a computer display

by using CMY inks on a page. Printing very light colours is

also difficult because spacing small ink dots so far apart does

not generate smooth colours.

Additive colour mixing is used for devices that normally

have a black background representing no colour

transmission. The opposite is true for printed maps in which

you instead perceive reflected light. Light that illuminates

paper passes through the printing ink and is reflected back

off the paper. The reflected colour is the colour of the ink. If

several layers of ink are overprinted on each other, reflected

light is absorbed differently by each layer of ink so the result

is a mix of the layers. If you use transparent ink in the three

primary colours, light will be absorbed by them and, in theory,

no light will pass through any combination of the colours

resulting in a black image (i.e. no reflection).

Printing on paper uses subtractive colour mixing and

transparent inks in cyan, magenta, and yellow. Cyan

transmits green and blue, magenta transmits red and blue,

and yellow transmits red and green. For example, if yellow

ink is printed on top of cyan ink on white paper, the yellow ink

absorbs blue light but transmits red and green; the cyan layer

then absorbs red light so only the green light reaches the

paper and is reflected back to the observer. CMY colours are

also referred to as process colours. Black (K) is usually used

as a fourth printing ink to create pure black text and line work

and better printed greys. The K means ‘key’ in four-colour

process printing since black is normally printed first and other

colours are keyed or registered to it. These pigments are

also used in ink and laser printers, which apply percentage

coverage of tiny dots to the paper.

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Additive and subtractive colour

PANTONE306 C

PANTONERhodamine Red C

PANTONE107 C

PANTONENeutral Black C

PANTONE485 C

PANTONE360 C

PANTONE7455 C

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6 Cartography.

Advertising mapsThe use of maps to sell.

See also: Branding | Copyright | Emotional response | Thematic maps

Opposite: Mockup of an advert for cellphone

and data coverage. The ad wants you to

believe in the extent of availability of the

product. The map uses perspective, tilt,

curvature and occlusion coupled with the

symbology to relay that message. Simple to

process and suggesting totality, the prism

heights are unexplained and even bleed off

the page and obscure text to infer it’s too

much to even show! The words reinforce the

idea of coast-to-coast coverage with no gaps

(despite the reality). The small legend acts as

a disclaimer that is positioned to ignore.

Perhaps the map that is used to advertise

more than most is the one that many people

wouldn’t even realise is being used in

that way. Google Maps™ is the go-to map

for millions of people each day. Most will

use it for general-purpose tasks such as

finding a location or seeking directions

but Google did not produce the map as an

act of philanthropy thinking that the world

needed one consistent map for anyone

to use. There is money to be made from

maps, and Google itself is neither a map

nor a search engine. Although its business

has proliferated into a range of markets, at

its core it’s an advertising company whose

revenue streams are predominantly from the

money it makes by putting adverts in front of

consumers.

Google rapidly realised that the map can act

as a proxy for an advertising hoarding. Every

time we use the search engine on the map

we’re looking not only at the map but at the

content that is being added. Over time, this

content has gradually changed to support

more advanced approaches. The map places

you at the centre and builds content around

you. If you search for a restaurant you are

going to see those that Google promotes

(because it is paid to do so) or which relate

more to you to encourage you to go there.

The same is true for a vast range of goods

and services that take you to other websites,

which may have content on them that Google

gets paid to show.

Considering people’s general liking for, and trust of,

maps, it’s no surprise they’re used heavily in advertising.

Advertising is designed to create a clear image in a

consumer’s mind. It does so by being as appealing as

possible. Cartographically, the aim is definitely form over

function as it attempts to create a favourable comparison to a

competitor’s product, to emphasise a clear corporate image or

to build trust, affinity, and demand for a product. Advertising

might be used to show where something exists but omission

and exaggeration are often used to build a picture. Graphic

clarity is often replaced by the need to convince someone

to buy.

Maps in advertising often play on a theme. Maps might

be used to show convenience or the spatial ubiquity of a

service. Conversely they might highlight exclusivity. Maps

are used to exploit the consumer, and the map itself is often

exploited as a framework for selling some partial version of

the truth. For instance, distances are sometimes warped to

show places as being nearer or more convenient. Coverage is

sometimes shown to be more than it actually is. So the map is

used to present a highly generalised version of reality that can

communicate the message immediately. Thus, the mapmaker

often applies a large dose of artistic licence to exaggerate

what they want to show and is creative in masking what they

don’t.

Maps used in advertising tend to be some of the most

inventive and pictorial. They often use very familiar shapes

such as the outline of the world or of a country which are

potent and recognisable symbols in their own right. They play

to the fact that the consumer is already familiar with the basic

structure of the graphic so the extent to which the image can

be modified, yet still retain familiarity, is much greater than for

maps that support other purposes.

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