SECTION 6
Basic map design decisions must be made in order to communicate information and data clearly, accurately and economically to users having a minimum of map reading skills. Factors which affect the design process include: the map user's requirements, his/her ability and knowledge of maps, the complexity of the information to be mapped, the available methods of map reproduction and costs. An understanding of the natural or cultural environment being mapped is also necessary to present a balanced reproduction of that region of the world.
The cartographer should work in a similar manner to the artist, beginning with a general plan and progressing to finer details. Based on the objective of the map, a design concept should be developed which takes into consideration the desired information content and symbolization. This concept, which controls the choice of a scale, should be tested on various parts of the map and adjusted as necessary.
All map designs should aim at producing more than one visual level. Information selected to be the foreground of the product will be the most obvious to the user and must be chosen carefully to fulfill the major objectives of the map. Examples of major objectives include the cultural features of topographic maps, the depiction of economic ore zones on geology maps, and rocks, reefs and other hazards on navigational charts.
Supporting information should be treated as background material and given a lower visual level by decreased size, colour intensity, contrast and, therefore, decreased overall importance. This information is often ranked by relative importance to the map subject. Information which does not support the subject of the map is visual clutter and should be eliminated.
As a general rule, the initial design should employ the minimum degree of contrast needed to ensure that all symbols are readable and that dominant symbols appear as such. Excessive contrast used at the outset results in a rapid buildup of heavy lines, large type and strong colour.
On all maps the subject matter should be organized and displayed in categories of similar items. Subdivisions of any one category should be shown by symbols representative of their relative importance within the category. The most obvious road on the map and in the legend, for example, should be the most important road in the category identifying the various classes of roads. Other roads will be treated in order of diminishing importance and with less visual impact. Related categories and their subdivisions should follow one another in the legend in order of importance.
A map user is first concerned with identifying the region covered by the map. The information used to do this will initially include the title, subtitles, key map and scale, followed by an examination of the map face.
The general arrangement of land and water, the depiction of relief and the general shapes of cultural and vegetated areas are the basic elements which provide a reader with a mental impression of the region depicted by the map. A clear visual distinction between land and water is the single most valuable item providing the map user with a fundamental orientation. The land and water areas should be clearly differentiated by the use of colour, tone or pattern over either surface.
Similarly, pale tones or subtle colours may be used to separate the prime map area from the surrounding region. Often the background of the crucial map area is left white so that small type and fine symbols can be seen more easily. The surrounding map area is given a tone or pale colour, often a neutral grey, to subdue it. This treatment creates an optical “window” allowing the reader to concentrate his attention on the prime map area. On less complex maps of a thematic nature, the reverse treatment is sometimes more effective. The critical area is given a light tone or colour to visually hold it together and to differentiate it from the surrounding information. This is particularly effective on informal maps which lack the common devices of ruled lines, borders, blocks or more formal placement of their various elements.
On most maps, the greatest volume of information is shown by a variety of line symbols. In areas where different line symbols cross each other there is a high probability of confusing the map reader. A common cartographic task is, therefore, the clarification of line symbols. This is most often done by placing a tone, pattern, or colour within the area for which a particular line symbol acts as a boundary. Geological and other scientific maps commonly use this technique to clarify what would otherwise be a confusing complexity of lines. The area tones, patterns and colours should be pale and subtle. If heavy tints are used the lines or symbols which must show through the colours or tones in these areas will have to be drawn more heavily. The result will be poor legibility (refer to Section 13, case study #5).
On many maps the most interesting or most crucial features are often relatively small in comparison to the total map area. These items can be made more visible by the deliberate use of emphasis or visual impact. Prominent colours or obvious patterns and darker tones should be restricted to small-size features. The colours red, orange and purple/violet are ideally suited to draw attention to small regions surrounded by light backgrounds. Black and dominant patterns are also used to give emphasis to small areas. Every tone, colour, pattern, and symbol selected must be evaluated for its effect in relation to the overall design.
The surface area used for the map face (the area within the neat lines) should be visually dominant. A good rule of thumb is to keep the map area to about 2/3 of the total area, with the remaining 1/3 for notes, surround, etc.
The oldest known and most extensively used “pleasing proportion” is the ancient Greek standard called the “Golden Section” which is a ratio of approximately 5 units to 3 units. This proportion can be used both for overall map sheet proportions and for such details as blocks within the overall design. The ratio 3:2 is probably the most used for legend blocks, being very close to the proportion of the “Golden Section”. These ratios are also appropriate for maps which will be photographed to 35mm slides.
In general the square should be avoided when the intent is to produce aesthetically pleasing artwork. It can, however, be effectively included as an inset within the overall “Golden Section” map face. The optical square which should be used is a slight modification of the true square, being 3% wider then high. It is aesthetically more pleasing but still appears “really square”.
This should be the single most obvious item on the map to permit easy recognition of the subject. The title should appear in the largest and/or boldest type used anywhere on the map without being too dominating. It should also be short in length and describe the area or subject portrayed. Such redundant terms as “Map of” and “Chart of” should be avoided.
When extra information such as District, Region, Province, State, etc., is added to the main title as a sub-title, it should be smaller in lettering size and weight than the main title. Type styles should be the same or be compatible with controlled spacing between lines of type.
The purpose of a key plan is to locate the map area geographically in relation to a larger context. It should only have enough geographic detail to ensure that the average reader will recognize the area easily. The primary map area must be outlined and labelled for ease of recognition within the location map.
An important feature of any map or plan is an accurate bar scale from which a range of measurements may be obtained. To be of maximum utility a cartographic bar scale has one primary sub-division placed to the left of “O”, all others being to the right of “O”. This single unit is in turn sub-divided into smaller, exact, convenient units which are appropriate for the scale and map use.
Scales should be neither too long nor too bold to avoid dominating the map. On a double line bar scale alternate sub-divisions should not be filled in as this dramatically increases the visibility of the scale and tends to make the alternate sub-divisions visually long and short.
The representative fraction, scale statement and graphic bar scale should be located together.
North arrows should be simple, accurate and unobstrusive. Unless otherwise noted, it is always assumed that the direction referred to by a north arrow is true north or geographic north (Figure 6.1), established by reference to the graticule. Standard mapping conventions dictate that the direction of true north coincide with the vertical edge of a map; this should be followed whenever possible to avoid confusion. Maps oriented in the planned direction of travel are exceptions to this rule, e.g., orienteering, canoeing or cross-country skiing maps.
There are other north directions in common usage, probably the best known being magnetic north (Figure 6.1) which is seldom identical to true north. The needle of a magnetic compass aligns itself with the direction of the local variations of the earth's magnetic field. The needle will tend to point to the north magnetic pole, which is currently located in Northern Canada 1400 kilometres from the geographic pole. The difference between true and magnetic north is known as the declination (Figure 6.1). A north arrow system showing this difference is a declination diagram, a common feature of most reference maps (Figure 5.14). As the magnetic field changes slowly, a useful declination diagram will include the correct declination, the year of its measurement, and the amount of annual change. In this way magnetic north can be easily converted to true north, and vice-versa, throughout the useful life of the map.
It should be noted that magnetic declination can be very significant and thus of major importance on any chart designed for navigation. In the continental United States, the angle ranges from 22° East to 22° West while in the Canadian Arctic it ranges from 0–180°.
A detailed isogonic chart, showing lines of equal magnetic declination and equal amounts of annual correction, should be referred to when constructing a declination diagram. Many coastal or marine maps can usefully incorporate a miniature isogonic chart as part of the valuable surround information.
Figure 6.1 Magnetic declination. (After A.N. Strahler, 1963)
The declination diagram also frequently incorporates a third north called grid north (Figure 5.14). This refers to the direction of the grid lines that are added to many maps and charts. When a grid such as the Universal Transverse Mercator grid is used in areas far from the equator the divergence between grid lines and meridians becomes very noticeable. The meridians converge on the pole while the grid lines remain equidistant. Thus, the declination diagram (Figure 5.14) should also show grid declination, the angle between grid north and (true) geographic north.
An important element of the surround of many complex graphics or maps is an explanation of symbols which have been used and are not immediately self-explanatory. These explanations are variously called Legend, Symbols, Key, Reference, Explanation, Conventional Signs, etc.
The organization of the legend needs particular care. The first consideration is always the manner in which the map or graphic reader will actually use the product. After consulting the title or possibly the key map, most people refer directly to the map face or diagram detail. When they see a symbol, pattern, colour or abbreviation which is unfamiliar or unclear, they seek an explanation in the surrounding notes. In keeping with the convention of reading from left to right and from top to bottom, the explanations should be laid out in a similar manner. The symbol should be on the left, and the notes explaining it to the right of the symbol.
People using the legend have to rely on their memory of the unfamiliar symbol to locate it in the list provided for them. This results in a number of design limitations, including the following :
i) The symbol in the list must be exactly as shown on the graphic, i.e. it must be identical in size, shape and colour. Many presentations are made with the actual symbols contained in rectangular boxes, followed by an explanation. These boxes represent a small portion of the map or graphic. Linear symbols contained in such legend blocks should run across the block to represent their continuing nature on the actual map face;
ii) Legends must be organized or ranked. All symbols which need an explanation must be organized into logical and closely related groups and sub-groups. Thus all forms of contour or isolines will be in one grouping; closely related species may be in another, etc. Within each grouping the symbols must be ranked so that normally the most important (to that map or map user) is listed first, and the others are then shown in descending order of importance;
iii) Symbols which do not appear on a product should not be listed in the legend. For series mapping, however, cross-referencing, economics and speed of production may dictate otherwise;
iv) Type (lettering) used for explanations must be simple and small. The lettering size should be the smallest which can be read by people of less than average eyesight, under realistic usage conditions;
v) Explanations should not be placed on separate pages of a report, particularly when the pages must be turned to read the explanations. Avoid printing legends on the back of maps for the same reason.
It should be noted that wherever possible items should be identified or labelled on the map face rather than including them in the legend, which is a relatively inefficient communication device.
The reading and quality of any map or graphic is greatly affected by the positioning of the names and lettering used upon it. When it is properly placed, the lettering will clearly identify the feature to which it refers without ambiguity.
The following set of guidelines may result in conflicting requirements in the production of a complex map. These must be resolved by the cartographer choosing the alternative which gives the greatest clarity:
i) Maps are normally read (viewed) from the bottom. Most names, numbers and labels should, therefore, be positioned so that they are either horizontal, or parallel to the lines of latitude on the map. The major exceptions to this rule are linear features and area names;
ii) Linear features such as rivers, canals, roads, etc., are named close to, parallel to, and normally on top of the feature. Lengthy features should be named more than once rather than relying on excessive letter spacing;
iii) Labels on linear features can be greatly improved by attention to the flow or alignment of the lettering. Names should be placed parallel to a straight section or smooth curve of the feature. Avoid all irregular or zigzag placements. The names for such natural features as bays, rivers, linear lakes, ridges, etc., should be aligned on broad areas or easy curves following the overall trend of that feature. Contour numbers are placed on breaks in the line and are aligned precisely with that section of the relevant line;
iv) The placement of vertical names (along meridians, grids and borders) needs attention. On small-size maps such names are normally oriented to read south to north so that they can be read looking from the right or east side of the map. On large-size maps the viewing position is taken to be the centre of the south edge. Letters will read south to north on the west edge and north to south on the east side;
v) Letters should not be placed so that they are upside down when viewed from the south map edge or the planned viewing position. For the purpose of definition the term “upside down” includes any angle past the vertical;
vi) Lettering should not be placed in a straight line on any diagonal, unless it parallels a linear feature. It is excessively obvious and visually disruptive, interfering with the readability of the rest of the product;
vii) The naming of adjacent features at angles close to the vertical needs particular attention. Frequent changes of direction should be avoided wherever possible;
viii) In naming areas (lakes, estuaries, basins, mountains, counties, regions, etc.) the name is placed within the feature if at all possible. When such features are irregular the names should be placed on smooth curves whose alignment broadly follows the trend of the feature. Letter spacing is often used to better indicate the extent of the feature named. Short names which apply to long areas may have to be repeated;
ix) As a general rule names should be placed so they do not cross marked changes in background colour or tone. Thus in coastal regions names are placed either on land or in the water, not across the coast or waterline;
x) Names take priority over all map symbols and details except area colours and tones. Lines and other map symbols must, therefore, be broken or eliminated beneath a name. As this obviously affects the continuity of information and may also result in the loss of essential details, point xi becomes a fundamental consideration;
xi) Names should be placed so that they do not interrupt other map information. If this is not possible the name must be placed to cause the absolute minimum interruption and loss of detail. If a name must cross a line or run into it, there is much less disruption if it crosses the line at right angles rather than at a shallow angle;
xii) The most common class of names used in mapping are those which are applied to point symbols. These names must be applied so that the point symbol and the initial letter of the name coincide as closely as possible. As people normally read from left to right, the ideal location for the name is immediately to the right of the point symbol, and slightly above or below its alignment;
xiii) If the positioning in xii is not possible, an acceptable position is immediately to the left of the point symbol, and again slightly above or below it;
xiv) If neither xii or xiii is possible the name can be centered slightly above or below the point symbol. The above position is usually considered superior as there are fewer letters in the alphabet with descenders (descending limbs such as “g”) then there are with ascenders (ascending limbs such as “d”). This will tend to ensure closer name placement to the point symbol and better name identification;
xv) Aligning a name precisely with any point symbol should be avoided as this can often create visual confusion, especially on those maps with unfamiliar names or terminology;
xvi) There must never be any doubt as to which point or feature a name refers. Names for point symbols should be placed a distance approximately equivalent to half the height of a capital letter from the symbol name. Rules xii, xiii and xiv should be used to manipulate complex areas to ensure points are labelled without ambiguity;
xvii) When applying names to point symbols located on linear features such as coastlines or rivers, the name should be placed so that it is not separated from the point symbol by the linear feature. Names of towns on rivers should be on the same side of the river as the symbol;
xviii) Coastal names can rarely be placed horizontally because of the usually complex shape of the coastline. A pleasing solution is to place many of the names seaward of the coastline and to curve them into the point to which they refer. Attempt to curve as many of these names as possible in the same direction and with similar curves;
xix) Names should not cross one another unless no other solution is possible;
xx) Names which must cross each other must be clearly differentiated by either the use of letter spacing or a change in the style or size of lettering that is used;
xxi) In general, use letter spacing as little as possible;
xxii) The entire sequence of letters in a letter-spaced name must be easily seen and read without error. It is often necessary to move point symbol names to clarify regional letter-spaced names in the same area;
xxiii) All letter-spaced names must have equal-appearing intervals or spaces, according to the visual perception of the cartographer. The spaces should not be measured mechanically.
The fundamental methods of lettering any graphic must follow the normal guidelines used to produce text (written) material :
i) Lower case letters are the norm and communicate more effectively than upper case letters;
ii) Capital letters are more obvious because of their increased size and angular nature but are less efficient than lower case. They should, therefore, be used sparingly and only be selected for the most important items to which particular attention is desired;
iii) Identifying land features by upright letters and water features by italic or slanted lettering has become a widespread convention. This should be followed unless an overriding reason prevents it, such as charts of entirely marine environments;
iv) The size and visual weight of a name should reflect the importance of that features on the map. The smallest and least important information must be easily read and reproduceable. The remaining class sizes are chosen with the subsequent smallest increment in size and weight of letter that will be clearly seen by the average reader;
v) Most punctuation marks are omitted from the face of a map for simplicity and to avoid confusion with other map symbols. Textual material in the surround is punctuated normally. The period is not used. The apostrophe is never used to indicate possession; thus “Harpers Ferry” and “pikes peak” are correct, and not “Harper's Ferry” or “pike's peak”. The apostrophe is used only for legal spelling, such as “O'Brien Creek”. The hyphen is used only to conform to legal spelling, e.g., “Geneva-on-the-Lake” and “Shut-in-Cove”, or for separating the two parts of joint names, e.g., “Bell-Johnson Channel”.
