Brig (Retd.) M.C. Dhamija, K.D Sood
Communication is the transfer of ideas, knowledge or information from one person to another though a medium in the form of audio perception, visual perception, odour perception or perception of physical contact. The most common and familiar form of medium is the audio & visual perception i.e. communication by spoken or written language. All audio perceptions are really specific sound forms and the visual ones are what we can generally term as graphics be they be language, pictures, sculptures & so on.
To be able to be understood a communication must have an order, though the order may not be always completely rigid. Purely visual communication relies soley on the process of visual perception to transfer information. How does this process of visual perception works in graphic communication, that we shall examine now.
The act of seeing by any person can be broadly classified in to 3 stages. The first is the entering of the light reflected from any source in to the eye of observer. The second is the reaction of stimulus of retina of eye which records the impression and sends it to brain. The third stage is the reaction of the brain, all the stages comprise the act of visual perception. The psychologists have framed certain laws regarding the effect of various forms and types on visual perception which can be summed up in the Gessalt’s laws of organisation which are as follows:
Size – Smaller areas catch attention
Continuity – Mere continuous areas give better clarity
Closed figures – Closed figures gives better impression than open areas
Proximity – The images which are closer give the impression of being one entity
Symmetry – The symmetrical form of grid tends to dominate more random forms of other details.
From the above classification of visual variables following can be achieved: Form, Size, Orientation, Density, Value, Colour
Colour is a very complex subject. The use of colour is a subjective matter and this is the most widely used and criticised variable used in cartography. There are three primary additive colour viz. Red, Blue and Green and three primary subtractive viz Cyan, Magenta and Yellow.
The accepted theory is that we perceive colours by different wave lengths of visible light. Any absence of wave length or a combination of different wave lengths of reflected light give us the perception of different colours (hues). Any hue can be achieved by combination of different colours in proper proportions.
Use of colour in cartographic designs is a highly subjective matter but a few general conventions do exist. Colour is the variable which achieves high contrast with a very small amount, and which in turn achieves high degree of clarify and legibility. This aspect is immensely useful while designing a graphic image.
Generalisation in a map is a basic thing. The very map itself is a generalised impression and all the symbols used are generalisation in one sense. Still however there are two main factors which are dominant in affecting Generalisation. These are:-
- Scale: The scale of map is by far the most limiting factor for generalisation. The scale depends on the (i) purpose of map (ii) limiting size of map for utility or other constraints such as standardisation of scales. (iii) The feasibility of actual field work such as in high mountainous or jungle areas the scale may have to be limited.
- The Purpose of Map: The purpose of map is the main thing about which a map user is concerned and all the items required by him in specific details have to be depicted on maps. For example a land use map will give much more detailed information with respect to cultivation and types of soils where as a topo map of same area may generalize all this.
A judicious combination of map purpose and map scale will evolve the generalisation policy. Since both the factors are interrelated a study of selection of details to be depicted and the omittance of other details will greatly help in fundamentally arriving at suitable conclusion about the scale of map within useful purpose of serving map user as per his requirement and such determining the degree of generalisation.
Graphic design is a difficult subject, but like wiring with words communication with graphic language of maps can be learnt. The preparation of a graphic communication is like that of a written communication, they must each be planned carefully so that the reader will be able to obtain as easily as possible, the information being conveyed. This phase of cartographic process involves, a variety of operations; setting upon the method of portrayal, choosing of lettering sizes and styles, specifying of width of lines, selection of colours and shadings, arranging of various elements in the map, designing of a legend and so on.
As already emphasized earlier, all maps are made with the object of communicating some spatial information to a reader or map user. Hence the complete process of map preparation i.e. compilation, symbolization, choice of scale, and other Cartographic process like selection of lines, tones & patterns should always be in tune with the requirements of man user so that the end product (map) will be effective in communicating to the user, the information he wants. If the map has not been properly designed it will be a cartographic failure. The aim of the cartographic design is to present the spatial data in such a fashion that the map, as a whole, appears as an integrated unit and so that each item included is clear and legible.
CLARITY AND LEGIBILITY
The communication by graphic image requires that the graphic elements be clear and legible. Although the various graphic elements in map have other functions to perform in a visual composition, one of their basic objective is to promote clarity and legibility.
Clarity & legibility are broad terms. A considerable portion of the test of achieving clarity and legibility will have been accomplished if the map-maker has made sure that the intellectual aspects of map users are not impinged with unintelligible or horsy redressing in any manner.
Once the geographical concepts underiving the purpose and data of a map are clear and correct, then legibility and clarity in the presentation can be obtained by the proper choice of lines, shapes and colours and by their precise and correct delineation. Lines must be clear, sharp and uniform.
The fact that symbols, lines and other elements of a map are large enough to be seen does not in itself provide clarity and legibility. An additional element that of contrast is necessary.
No element of cartographic technique is so important as contrast. The degree to which a map appears precise and sharp dependent on the contrast structure of the map.
Contrast is achieved by varying the visual characteristics sizes and shapes, pattern, value (relative darkness), and the characteristics of colour.
CONTRAST OF LINES AND SHAPES
Most maps require the use of several kind of lines, each symbolising some geographical elements or concepts, such as coast lines, rivers, railroads, various political boundaries and so on. In order to make each clearly distinct from the rest it is necessary to vary their character, design or size in some map.
There are infinite variety of shapes available for the cartographer to change the graphic elements. It is up to the cartographer however, to let his imagination roam and to consider critically those maps on which the line and shape structure appear well designed in order to become familiar with the range of possibilities.
CONTRAST OF PATTERN
The patterns are composed of dots (stripling) lines, or combination. The possibilities are unlimited.
Every patter whether composed of dots / lines of a combination has several characteristics (i) Texture (or Density) that is the spacing of marks, usually specified by the number of lines per inch; the greater the number the “finer” the texture (ii) arrangement (iii) Orientation.
Cartographer may employ all these characteristics of pattern to obtain contrast. The important point in obtaining contrast among patterns is varying as many of the characteristics as possible, rather than trying to hold some constant.
CONTRAST OF VALUE
Value contrasts are the most important elements of seeing and every one is familiar with the ease with which it is possible to recognise objects represented in drawings or photographs merely by their tonal or value structure. Since any thing that can be seen must have a value rating and because any thing must vary in value if it is to be easily distinguished from its surroundings. It follows that the contrast of value is one of the fundamentals of visibility.
Any object or a group of units on a map has a value rating. Width of lines, areas with patterns, black or lettering in names, the title, the legend, the coloured areas and so on, are all value areas, and their effective arrangement within the map frame is a basic part of map designing. One of the most important ways in which the cartographer uses values, is in presenting a grades series of information. Thus for example, geographical phenomena such as variations in rainfall, depth of oceans, elevation of land, density of population and so on, are usually depicted by some technique that depends for a large portion of its effectiveness upon classes as differentiated by value contrasts.
FIGURE – GROUND
In any map, more so in small scale thematic maps, the immediate perception of the fundamental elements in the map is of primary importance. The reader must be able to focus immediately on the characteristics that the cartographer had as his objectives without fumbling and groping to find what he is supposed to be looking at. The most important element is graphic communication the leads to such quick recognition is called the figure – ground relationship.
This is a complex field of study still under intensive investigation by students of perception. Nevertheless some of the basic principles can be outlined.
4.1 Differentiation must be presented in order for one area to emerge as figure. The figure area must be homogeneous. Such differentiation must be obtained in a variety of ways, such as by colour, value and texture.
4.2 Brightness or high value tends to lead towards figure differentiation on a map.
4.3 Closed figures, such as islands, entire peninsulas or countries, and other complete entities are more likely to be seen as figures than if they are only partially shown.
4.4 Good contour is a catch-all term that includes the characteristics of “continuous appearing” “symmetrical” and simplicity of visual forms, all of which lead towards figure-ground differentiation.
4.5 Texture, in the broad sense of it being a basic complex of articulated marks tends to lead towards the emergence of figures.
4.6 Area is important in leading to figure ground differentiation. Generally the tendency is for small areas to emerge as figures in relation to large areas.
Colour has important effects on the clarity and legibility of a man, since it effects the readers ability to distinguish fine detail, to read the lettering and to see the boundaries.
Even the small amount of colour seems to produce remarkable differences in legibility and emphasis on maps. A small amount of colour used as light tint tends to subdue the visual clutter of lines, point symbols, and lettering. It is an important element in the figure-ground relationship and it acts as a unifying element in the visual composition or organization of a map. For example a tint on the land clearly helps to identify its shape and distinguish it from matter.
For the various elements of cartographic design, colour is probably the most interesting and yet also most frustrating to the cartographer. The use of colour is also greatly complicated by well-established conventions in cartography that often lead to contradictions. Colour in mapping is a subject that will remain controversial for a long time. In spite of its complexities it is much sought-after because of the advantages referred to above.
Although man can see different colours side by side, it is difficult for him to recall colours, and we must conclude that in this respect he is not very much sensitive. Relatively man appears to be more sensitive to red, followed by green, yellow, blue etc. In terms of its effect on the readers’ ability to distinguish fine detail, monochromatic light is superior to polychromatic, while yellow is the best background colour, and blue the poorest.
Convection plays a large role in the employment of hues in cartography. One of the most firmly established convention is the spectral progression of colour for layer tinting of elevations. There are also many connotations associated with hues: red, yellow and orange with warm temperatures, blue green and grey with cool yellow and tan with dryness and course vegetation; brown with land forms and contours; green with vegetation and so on.
Of the three dimensions of colour value is probably the most important in terms of fundamental perceptual aspect of map design. As was observed in connection with contrast, value is basic to clarity and legibility because of effect of value contrast in definition. The basic precep is that the greater the value contrast the greater the definition and the greater the clarity and legibility. The fundamental rule is that the darker the value the greater the magnitude.
In terms of graphic composition, it is well to use areas of extreme values with caption since extreme values tend to dominate. Dark blues for oceans or deep colours on political areas will generally overshadow the other parts of a map.
Designing a visual composition requires a number of preliminary decisions involving what is called by the general term “balance”. These involve problem of layout, concerning the general arrangement of the basic shapes of the presentation. The basic shapes may include, the land water passes, legends, boxes, colour areas and so on.
Balance in graphic design is the positioning of the various visual components in such a way that their relationship appears logical or in other words, it does not unconsciously or consciously disturb the viewer. In a well-balanced design nothing is too light or too dark, too long or too short, or too small or too large, Layout is the process of arriving at proper balance.
Visual balance depends primarily upon the relative position and visual importance of the basic parts of map and thus it depends upon the relation of each item to the optical centre of the map and to the other items and upon their visual weight. The aim of the cartographer is to balance his visual items so that they look right or appear natural for the purpose of the map.
The easiest way to accomplish this is to prepare thumbnail sketches of the main shapes and then arrange them in various ways within or around the map frame until a combination is obtained that will present the items in the fashion desired.
Organizing and outlining a graphic presentation is always an important part of cartographic design, but it is of paramount importance in thematic cartography. Any component of a map has, of course, an intellectual connotation, as well as, a visual meaning in the design sense.
After structuring of the major components has been decided upon, attention must be shifted to the second stage of graphic outlining. Often the problems of cartographic design for a series of maps, whether reference or thematic, call for the preparation of one or more “trial maps” in order that primary decisions may be made regarding various forms of symbolism, lettering styles, area patterns, consistency of layout and many other important design elements. Many times the opinion of map users is taken into account before decisions are taken.
TITLE, LEGENDS AND SCALES
These elements have denotative function in identifying the place, subject matter, symbolisation, etc., but they also serve as graphic masses that can be positioned to provide the graphic organization of a map. Generally, fragmentation of the map should be avoided as much as possible.
EFFECTS OF REDUCTION
With the introduction of scribing technique many maps are constructed at the final reproduction scale, nevertheless a considerable number of maps are still prepared by “Pen & Ink” methods and these are usually drafted at a scale larger than the publication scale, that is for reduction.
This is done for a variety of reasons, the most important of which is that it is often impossible to draft with precision. Also reduction “sharpens” the line work of the drawing. It requires the anticipation of the finished map and the designing of each item so that when it is reduced and reproduced it will be “right for the scale”. A map must be designed for reduction as much as for any other purpose.
Even in spite of the evermore range of availability of automated systems and softwares, it is obvious that human interaction for an optimum design is in escapable.