37. Diagrams and Line Illustrations

Diagrams proliferate in the work of a technical writer. They are probably the most common form of information presentation. Diagrams are two-dimensional line representations, usually intended (in old technology) for line block or line plate reproduction. They often employ symbols or simplified blocks to represent the objects or functions involved.
These symbols may be the subject of standards or specifications, with strictly formalised sizes and shapes. Many symbols now come as part of specialist software to ease the workload — the old-fashioned rub-on transfer is still used in some cases, though, but rarely at top level. Symbolic diagrams include graphs, maps, charts, hardware and functional drawings, circuit diagrams and flowcharts. Diagrams are useful in the presentation of statistical, symbolic or functional information. But more elaborate forms are needed for an adequate depiction of engineering hardware.
Line Illustrations
The commonest illustrations for equipment in technical documentation are line perspective drawings. These pictorial drawings are designed to convey the shape of objects and the position in space of the relevant parts. They may also illustrate the components used in assemblies and sub-assemblies, and the way they fit together and come apart.
Line illustrations are reproduced in a single solid colour with no tonal distinction. They may be black and white or coloured, using a mechanical tint, stippling or hatching, which simulate a variety of tones.
In the old technology, which you may still come across — hence our interest here — most illustrations were produced “twice up” on a Bristol board or even linen, by tracing over a pencil draft. Where modern technology is used the whole process is done on-screen, eliminating a number of the stages.
The term line illustration is used for any illustrative material which has no tonal variation, and which is suitable for simple line plate printing. Realism is often added to line illustration by means of perspective.
Next: 38. Perspective Drawings.


July 28th, 2006 at 3:36 pm
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