Design principles for technical and scientific illustrations

There are many types of illustration styles and approaches. Select a style that is appropriate for the publication’s content and intended purpose. Ready-made illustrations can be sourced from online libraries, but you might need to commission illustrations that are relevant to your content.

Be wary of using clip art because it is often generic, low quality and inconsistent in style, and can make your publication look less professional.

When using multiple illustrations in a publication, keep them consistent in technique, style and presentation. They can be included as:

  • figures that directly illuminate the text
  • supplementary images that support and are relevant to, but are not directly mentioned in, the text
  • decorative elements.

Standard conventions for technical and scientific illustrations include:

  • standardisation of the light source across illustrations
  • a standard shading formula – for example, upper left highlight, then intermediate tone, then darkest tone, then reflected light at bottom
  • reference to a scale
  • items arranged according to function
  • an orientation in relation to the viewer
  • if published online, alternative text for accessibility.

Figure name or title

The following principles are recommended:

  • Number illustrations consecutively within the document (e.g. Figure 1, Figure 2, Figure 3), or by section or chapter (e.g. Figure 2.1, Figure 2.2, Figure 4.1, Figure B5). Numbering by section is useful because changes in one section will not affect figure numbering in another section. This is especially important in long documents or those that have many figures. Alternatively, illustrations could be named Plate 1, Plate 2 and so on, if there is a requirement to separate illustrations from figures within the publication.
  • Place the title as its own paragraph below the illustration, not within the illustration. This convention should also be used for web-based publications.
  • Use a title that describes the figure content, including the date, if appropriate:
Figure 3     Human muscle groups
  • Use minimal capitalisation (only capitalise the first letter of the first word of the title and proper nouns).
  • Use minimal punctuation to keep titles clean and uncluttered: follow figure numbers with a tab, not a colon, and do not place a full stop at the end. Using a tab also helps align the names properly in an automatically generated contents list of figures.
  • Spell out abbreviations in full in the title, wherever possible. Put any necessary detail in explanatory figure notes. The title should not cover more than 2 lines (preferably 1 line).
  • For a series of illustrations, give the same information in the same order.