Cartography - Esri chapter a.pdfWhereas the principal task of map design is in the decisions taken...
Transcript of Cartography - Esri chapter a.pdfWhereas the principal task of map design is in the decisions taken...
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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