So if information visualisation is an appropriate solution to a design problem, the data is there, and the client and stakeholders are convinced of its value, how are designers to proceed? They need to begin by understanding the nature of the information, where it comes from, how and where it is used, what insights users will be looking for and their relative importance. Financial traders will be more interested in seeing changes in existing data relationships (see Thomson Financial example), while researchers may wish to find new data relationships. The needs of beginner and expert users may also need to be considered, particularly if training will be limited or some people will only use the tool infrequently.
Issues of perception, cognition and visual psychology need to be taken into account when considering how to present, contextualise and prioritise information, and support its manipulation. These relate to the number of dimensions of data presented, spatial positioning and relationships, colour and tone, and dynamic changes in these elements. At the level of interface and human-computer interaction, the designer needs to analyse the tasks to be supported, and address comprehensibility, navigability and the effectiveness of
any solution, including its usability. There may be a visual metaphor around which an interface can be structured. Visual I | O’s Angel Shen-Hsieh develops metaphors by ‘discerning the mental picture that expert decision-makers have.’
Developing interface concepts may begin with sketching but will likely require more sophisticated prototyping as, unlike many areas of design, sketches don’t provide a good basis for user (or even heuristic) testing. It is also important to work with the people who manage the data the tool will draw from, and those responsible for its implementation, to ensure the data can be delivered in the form it is needed and that the tool will perform quickly and reliably. The designer will also need to address the overall quality of experience of the product and the engagement of the user, considering visual appeal, information design and typography and interaction style.