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Illustrations - TechWriter Wiki


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For professional publications, illustrations (pictorial information) will often be produced produced by a professional illustrator, and not by the writer (writing and illustrating are generally accepted as being two separate disciplines). However, Technical Communicators may be responsible for commissioning illustrations, and for controlling their production and inclusion into the final publication.

Increasingly, and particularly for 'in-house' design or user documentation, they will be required to produce their own illustrations. Any Technical Communicator should be more than capable of producing flowcharts, or graphs and charts, for inclusion in their documents.


The first question is to consider whether illustrations are actually required in a document. Then, consider what illustrations will be required. When answering these two questions, it is essential to remember that illustrations are always there to support the text, or to provide detail that cannot be (as) easily represented in textual form.

Illustrations in technical manuals should be functional, and only used for increasing or improving communication. There should never be an illustration in a technical communication that does not directly add value to the communication. The most common culprit of violating this rule is the use of clip-art in PowerPoint presentations, where the illustration seems to be there purely to break up the monotony of an all-text presentation, or to fill up space where the slide only consists of half a dozen short bullet-pointed lines.

Primary considerations

  • What is the purpose of the illustration?
  • How or in what form is the illustration to be reproduced?
  • Time and money

Get to know the manufacturer's drawing system. Understand and use standard symbols or conventions.

When drawing illustrations by hand, it is useful to draw illustrations 150% - 200% larger than actually required and then reduce them - this allows for a sharper resolution. (Note that this is not true for electronic drawings using vector graphics.) Certainly, never draw smaller and then have it blown up (especially with electronic drawings) as this will probably result in a loss of resolution.

When using a drawing package, always use vector graphics. If the package does not support this, draw the images at the size they will ultimately be used (especially for on-line documentation) - scaling raster graphics up or down can lead to undesirable results.

Planning a series: Consider cases where there may be many illustrations of different aspects of the same product. Is it possible to use a common viewpoint, or scale, etc.

Consider every possible use of the illustration (e.g. whether specific users have specific requirements). It is easier to accommodate additional requirements from the outset rather than have to re-work later.

Consider methods of annotating drawings (whether the text/call-outs should be a part of the illustration or not). It may be useful to have them external to the illustration/superimposed later (or at least outside the picture area), in case the illustration is shrunk or re-used.

Design, construction or manufacturing diagrams are seldom suitable for user documentation, and should be re-drawn according to the user's requirements.

Sources of information for illustrations

  • The product itself
  • Design department, but design illustrations are seldom in the correct format for user documentation
  • Sales/marketing department - may have some already (`artist's impression', etc.)

Commissioning illustrations

Whether the illustrations are being produced in-house by a colleague, or by an external agent, the same information will need to be given.

Instructions to the illustrator:

  • The printing method that will be used;
  • The ultimate use(s) of the illustration (for example, sales literature, installation instructions, etc.);
  • The type of illustration required;
  • The level of detail required, and the view required;
  • Coloring requirements: whether the image should be in black and white or color, whether shading or stippling is allowed, etc.;
  • The (final) size (and orientation - landscape or portrait) of the illustration;
  • The deadline by which the illustration is required (and any milestones, draft dates, etc.).

Commissioning photographs

  • Try to arrange for the photographer to view the product at the same time as the writer, in order to limit disruptions.
  • Make sure that the photographer knows what you want to achieve
  • Make sure that the photographer knows how the photographs will be used/reproduced.

Positioning of illustrations

Overriding factors: Should be as near as possible to the text to which it relates; should be able to see the text as well as the illustration at the same time.

Should always be referenced by name/number.


  • Along side (or above/below)
  • Facing pages
  • Throw-clear sheets

Consider the positioning of illustrations in multilingual documents - need to be where they can be seen for all languages (duplicate if necessary).

Ref. also to "Structuring information", and make sure that it is consistent.

Types of illustration

There are many different types of illustration that may be used in technical communications. This guide divides these into four categories:

  1. Physical system diagrams
  2. Conceptual function diagrams
  3. Charts and graphs
  4. Photographs

Physical system diagrams

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Physical system diagram

Physical system diagrams are essentially `pictures' of actual physical things. They are trypically 'true to life' and show the system or object as it actually looks. This could include isometric drawings of machines, and so on.

Conceptual function diagrams

Explanatory/conceptual diagrams

Pictorial function diagram

`True to life' (as-is) overall view of the system and the functional relationship of its main units. May be `exploded', but shows approximate physical positions of the components.

Shows the physical layout, as distinct from the operational layout (i.e. where the components are). Useful for wiring/piping diagrams.

Functional block diagram

Functional relationship between components (represented by blocks, not actual pictures). Useful for showing interfaces.


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Flowcharts are best suited to showing the flow of control or information, or for illustrating algorithms. They are also good for showing the dependency of operations in a system, such as timing, or critical paths.

See also: Flowcharts

Charts and graphs

Charts and graphs are typically used for presenting statistical data.

Try to avoid making charts overly 'busy'. For example, there is little point in providing 'three-dimensional' shapes just because you can, if it is easier to concentrate on the data using two-dimensional shapes. Mircosoft's Office suite of products (and in particular Excel) provide many bells and whistles for 'jazzing up' charts and graphs - but just because they are provided does not mean that you need to use them. Often, simplicity equals clarity, and as a Technical Communicator you should always be striving for clarity.


Charts are useful for presenting statistical data consisting of quantities or percentages across several categories. The most common forms of charts are bar charts (sometimes called column charts), and pie charts - probably because these two are easily-generated in Microsoft Excel and other spreadsheet packages. However, as evidenced in Robert L Harris's Information Graphics, A Comprehensive Illustrated Reference, there are many, many alternatives to these.


Best suited to statistical data: trends or movements (such as sales figures over a period)


If photographs have been specifically requested in a publication, then these will more often than not be commissioned from a professional photographer or illustrator. However, as digital cameras have increased in quality and decreased in price, it may be feasible to take your own photographs. This is especially worth considering where the client has not stipulated the use of photographs, but photographs will provide the best way of illustrating a product or situation.

May not always be possible (product not made, etc.).

Note: Photographs can often be used as the basis for other illustrations (e.g. tracing line drawings from them, highlighting specific parts/lowlighting others, etc.).


Photographs should be taken from an angle that shows the required information, and preferably from the same angle that the user will see.


Pay careful attention to lighting - make sure that all required detail is visible. Consider the contrast; make sure that required detail is not in shadow.


The photograph should include enough surrounding detail to allow the user easily to identify the part of the overall product that is being photographed.


Consider also photo retouching and airbrushing.

Need to know the method of production, screen size (screen used to make dot patterns for tonal effect) and reproduction size before re-touching, as this will influence techniques that can be used.

Airbrush drawings can be as good as a photograph (but a lot cheaper/easier to get) if done properly. Useful if the product hasn't actually been made yet. Also `wash drawings' (not as realistic) and pencil drawings.

See also:

(Screen shots are essentially a type of photograph, originally being actual photographs in pre-Windows days, although nowadays they are most often captured electronically.)

Illustration techniques

These generally apply to system diagrams.

Line drawing

Black lines on a white background (or vice versa). Simplest to produce, and often the least expensive.

Consider also shading, mechanical tints, stippling

Isometric drawing

3-D representation, with angles at 30 degrees (or 45 degrees, although this is less common), usually giving a complete picture of the object. Will generally use exact measurements, so is useful for engineering drawings.

Can be:

  • External view: Drawing of the object as seen.
  • Cutaway view: 3-D version of a sectional view.
  • Exploded view: All parts in the right position but separated. Useful for assembly instructions or parts list. May need to place in a `Z formation' to fit it all on the page.


Isometric illustrations may be drawn using perspective. With perspective, the item is drawn with distant parts smaller, but this is only really perceptible on long objects. These illustrations are more difficult to produce, and therefore more expensive, but are more realistic (and therefore used more for sales/publicity material).

See also one-point perspective e.g. the inside of a room or cabinet.

Orthographic drawings

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Orthographic illustration

Orthographic drawings are two-dimensional ('flat') views of an object. They are typically black-and-white line drawings, although other illustrating techniques could also be used (for example, color, computer-generated illustations also work well). The key point aboutorthographic illustrations is that they are to-scale. Because of this, they tend to be used for showing dimensions or clearances for objects.

May use the `attenuated background' technique, where the overall shape (or area of detail) is inked in a heavier weight to emphasize it. This is useful where one specific element or aspect of the object is being described, but it is required to show the placement of this element within the overall object.

May use `shadow line' to emphasize the bits that stand out or sink in (looks as though light coming from one side).

See also Illustrations: Orthographic drawings.

Sectional view

Type of orthographic drawing, but with a bit of it cut away showing hidden detail. (Useful for showing principles of operation or flow paths.)

Areas of material that have been cut through should be indicated (such as by hatching or stippling).

Can take a section through any plane, but normally cut through the middle. Need to show where section is taken, possibly on another elevation (mark the second elevation "A-A: and on the sectional view, indicate "section through A-A").

Note: Some users may not understand these, as they can't physically see the cross-section.

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