Using Visuals Effectively in Technical Communication

Visuals are essential in technical communication because they clarify complex ideas and make information easier to understand and remember. Diagrams, charts, and tables allow readers to grasp relationships and patterns quickly, improving efficiency by presenting large amounts of data at a glance. Well-designed visuals not only engage readers and break up dense text but also reduce the risk of misinterpretation, ensuring clearer and more accurate communication—especially in fields where precision and safety are critical.

Visuals can take many forms, depending on subject matter and audience needs. Table 4.1 shows some common types.

Table 4.1 Common Types of Visuals in Technical Documentation

Visuals are powerful tools for the following reasons:

• Visuals summarize and organize information. For example, a table could effectively consolidate key points at the beginning or end of a report.
• Visuals enable comparisons. For instance, a bar chart is effective for comparing the incidence of heart disease across different demographic groups.
• Visuals illustrate relationships. A graph could effectively display the correlation between smoking and the development of lung cancer.
• Visuals emphasize key points. For example, a flowchart might highlight the essential steps in an engineering process.
• Visuals transcend cultural and language barriers. A well-designed graph is interpretable in multiple languages, making it accessible to a global audience.

Choosing Visuals

You’ll likely use various types of visuals in your assignments and reports. The following subsections outline best practices for specific types of visuals.

Tables

Tables are a valuable tool in technical communication because they allow you to present complex or detailed information in a clear, organized, and easily scannable format. Unlike prose, which requires the reader to extract and mentally organize information, tables arrange data into rows and columns so that patterns, relationships, and exact values can be seen at a glance. They are especially useful for presenting numerical data, specifications, or comparisons where precision is essential. In engineering, for example, a table of material properties enables readers to quickly compare density, tensile strength, and thermal conductivity to select the most appropriate material for a specific application.

Table 4.2 is an example which has been designed according to best practices—using concise headings with units and consistent numerical formatting:

Table 4.2 Material Properties of Common Structural Metals

Bar Graphs

Bar graphs are excellent for showing differences across categories or within series. Use them for general comparisons when precise measures aren’t critical. If specific values matter, label each bar with its value. Fig. 4.1 shows an example of a clustered column chart comparing tensile strength of five alloys at two different temperatures with bars labelled with the measures. Categories are displayed along the horizontal axis and values on the vertical axis. This makes it easier to compare multiple data series side by side.

Fig. 4.1 Tensile strength decreases at higher temperatures for all alloys, with titanium alloy maintaining the highest strength retention compared to the others.

Note that the category labels in this case have been written on the diagonal because of space constraints. If category labels are long phrases, putting them on the vertical axis with measures along the horizontal axis could avoid cramping.

Stacked bar charts are useful for showing proportions within categories. Consider Fig. 4.2, showing the material composition of different battery types.

Fig. 4.2 This chart shows the percentage composition of key materials in various battery types. Lithium-ion and solid-state batteries have the highest lithium content, nickel–cadmium batteries are dominated by nickel, and lead-acid batteries contain a majority of lead, highlighting distinct material priorities for each technology.

The material composition of battery types is best shown as a stacked bar graph because it shows the whole–part relationship clearly. Each battery type is represented as a single bar that adds up to 100%, so it’s immediately clear how much each material contributes to the whole battery. It also allows direct comparison of total composition patterns. Note that the battery type labels run horizontally so that they fit comfortably on the graph.

Line Graphs

Line graphs are especially useful in engineering and technical communication when you need to show how something changes continuously or over an ordered sequence. They’re one of the most powerful tools for revealing trends, patterns, and relationships in data. For example, Fig. 4.3 could help stakeholders choose the better-performing turbine based on efficiency loss trends over time.

Fig. 4.3 Both turbine models lose efficiency with increasing operating hours, but Model B maintains a slower rate of degradation, suggesting better long-term performance.

Note that lines in the graph only approximate the values between data points. To ensure line graphs are used ethically, clearly state if any smoothing or transformations have been applied. Choose axis scales and intervals that accurately reflect the magnitude and pattern of change.

Area Graphs

An area graph is a variation of a line graph where the space under the line is filled with color or shading to emphasize the magnitude of the variable. In engineering contexts, area graphs are often used to

• show how a quantity changes over time while also highlighting the cumulative size or proportion of the values; or
• compare multiple related datasets by stacking them, which reveals both their individual contributions and their combined total.

For example, in renewable energy engineering, an area graph might display the daily power output of solar, wind, and hydro sources stacked together, making it easy to see not only how each source fluctuates but also the total available power at any point. This function is illustrated in Fig. 4.4.

Fig. 4.4 The graph highlights both individual fluctuations in each energy source and the total combined output, showing how renewable sources complement each other across the week.

Area graphs, similar to line graphs, can show trends and totals across categories. They are effective for showing cumulative data but less so for displaying specific series values within totals.

Pie Charts

A pie chart is a circular chart divided into slices, where each slice represents a proportion or percentage of a whole. The size of each slice corresponds to its share of the total, making pie charts an intuitive way to visualize parts-to-whole relationships. In engineering, pie charts are especially effective for illustrating proportional data such as material composition (e.g., the percentage of steel, aluminum, and composites in a vehicle’s body), energy source mix (e.g., the proportion of electricity generated from renewable versus non-renewable sources), maintenance cost distribution (e.g., labor, parts, downtime, and overhead), and project budget allocation (e.g., design, testing, manufacturing, and quality control). They provide a clear visual impression of how parts contribute to a whole, making them useful for highlighting dominant categories or overall balance. However, pie charts are less effective when precise value comparisons are needed, especially if the differences between categories are small; in such cases, a bar chart or stacked bar chart offers greater clarity. They can also become difficult to interpret if there are too many small slices or if category percentages are similar, which can visually blur distinctions between them.

Fig. 4.5 is a good use of a pie chart because the data represents a composition that adds up to 100%, with a small number of clearly distinct categories. Each slice visually conveys the proportion of a specific material in the battery, making it easy to see which materials dominate (e.g., nickel) and which play smaller roles (e.g., manganese).

Fig. 4.5 Nickel makes up the largest portion of the battery composition, followed by cobalt and lithium, highlighting the importance of sourcing and managing these critical materials in electric vehicle manufacturing.

Pie charts are most effective for providing a quick, big-picture view of proportions rather than fine-grained comparisons, as the human eye is not good at judging small differences in angles. To maximize clarity, slices can be ordered from largest to smallest, with distinct, meaningful colors used to reinforce the message. Labels can be placed on or beside the slices as long as this doesn’t clutter the graph.

Diagrams and Photographic Images

Diagrams are invaluable in technical reports, especially for explaining complex mechanisms. For example, a diagram of a vehicle’s safety belt locking mechanism can convey information about form and functionality far more effectively than a written text. A well-designed diagram with clear labeling or a legend can simplify complex designs because it strips away unnecessary detail so the reader can focus on the most relevant features. Remember, however, to tailor diagrams to your audience’s expertise. Technical readers, such as engineers, can interpret detailed diagrams (e.g., complex circuitry), whereas non-technical readers may require simplified visuals (e.g., simple labeled boxes).

Photographic images are the better choice when realism, authenticity, and an accurate depiction of an actual object or condition are essential—when readers need to recognize something exactly as it appears in the real world. They convey far more visual detail than diagrams, which can be either an advantage or a drawback depending on the context. For example, in a bicycle repair manual, a photograph of the gear assembly would reveal metal textures, grease, reflections, and parts of the surrounding bike frame—details that might distract from the form and arrangement of the components. In such a case, a simpler black-and-white diagram could focus attention more effectively on the parts themselves.

When integrating images, remember the following points:

• Simulate the typical angle of vision.
• Crop unnecessary details to focus on relevant elements.
• Label specific features.
• Include a size reference, such as a coin or a pencil, to provide context (if appropriate).
• Reference images by figure number in your text.
• Obtain permission for images owned by others.

By using diagrams and photographic images judiciously and adhering to these best practices, you can make your technical documentation clear, precise, and engaging for your audience.

Making Visuals Accessible

Accessible technical documents present visual information in a way that is clear, consistent, and easy to understand. For example, in a manual for a complex machine, high-contrast diagrams, simple and legible labels, and concise captions can significantly improve comprehension. These elements work together to help readers quickly understand how the machine operates.

Clean, well-organized visuals enhance usability, allowing readers to find and interpret information with ease. To achieve this, prioritize clarity and consistency in your visuals, Use the same terms and labels throughout the document, place visuals next to relevant text where possible, and avoid unnecessary clutter. In the following section, we’ll explore how to combine visuals and text effectively, with a focus on accessibility.

Integrating Visuals and Text

In technical communication, combining visuals with text is essential for conveying complex information more clearly than text alone. When used well, visuals can clarify concepts and improve understanding. When used poorly, they can cause confusion. The following guidelines will help you integrate visuals effectively:

• Place visuals next to the related text so that readers can easily connect what they see with what they read. When a figure, diagram, or table appears far from the section that explains it, readers must flip pages or scroll back and forth, which disrupts their focus and increases cognitive load.
• Avoid placing figures immediately after headings. Instead, introduce each figure with at least one sentence that explains its purpose. Dropping a visual directly under a heading without any lead-in text can leave readers uncertain about why it is there or how to interpret it. A brief introductory sentence sets the stage, clarifying the figure’s relevance before the reader examines it.
• Follow visuals with explanatory text that expands on what the reader sees. Use visuals to show structure or relationships and use text to explain the underlying details or implications.

Visuals provide readers with the “big picture” at a glance, while text fills in the essential details. In the next example, we’ll see how a visual supports the explanation of a mechanical system, making its operation easier to understand.

In the example, the first paragraph introduces the system’s dual-axis mechanism and basic functionality before presenting the figure. It also mentions key components, such as microfiber cleaning pads and guide rails, to prepare readers for what they will see in the diagram. The figure, then, displays the spatial arrangement of the components, while the subsequent paragraph explains the operational details, such as how the sensors monitor the contact pressure and how the microprocessor adjusts the cleaning parameters based on the environmental conditions. This integration allows readers to easily understand the system’s physical structure from the visual while gaining a deeper understanding of its functionality through the accompanying text.

Labeling

Labeling visuals means clearly naming important parts, features, or data right on a diagram or illustration. Good labels help readers understand complex visuals by pointing out key elements and showing how they connect. When you create labels,

• use consistent formatting;
• keep text concise;
• position labels close to their referenced elements; and
• maintain a clear visual hierarchy that distinguishes labels from other text elements.

Captions work alongside labels to connect visuals to the main text by providing context and highlighting what is most important. A caption typically includes a figure number and a brief, description. Use a consistent numbering system—such as Fig. 1, Fig. 2—in the order visuals appear in your document. Keep captions short but informative, focusing on the visual’s main point without adding unnecessary detail.

For example, the VertexSphere window washing system diagram uses clear labels to identify its key components—power supply, cleaning pad, water jets, sensor, and control unit—placed next to their corresponding parts. The caption, Fig. 4.6 Mechanical components of the VertexSphere window washing system, including cleaning pads, sensors, water jets, and power supply, provides both a sequential figure number and a concise description of the content of the figure.

Ensuring Clarity in Figures and Text

Visual clarity is essential for effective technical communication because poorly designed visuals can confuse readers and obscure key information. To support visual clarity, use high-resolution images (at least 300 dpi for print) so details remain sharp when viewed closely. When resizing, maintain the original proportions to avoid distortion, which can misrepresent measurements or spatial relationships. This is especially critical in engineering, where accuracy is key to correct interpretation. Consistent shapes, line weights, and styling across diagrams also make visuals more polished and easier to interpret.

Text within figures is just as important as the graphics themselves. Choose fonts that are easy to read for labels and annotations, and use a consistent style throughout all visuals. Serif fonts, such as Times New Roman, work well for print because their letterforms remain legible at smaller sizes. A minimum of 10 pt is generally recommended to ensure readability without overpowering the diagram. Provide adequate spacing around labels so they do not feel cramped or difficult to trace back to their corresponding elements.

Clear visuals combined with consistent typography are not just matters of design. They directly affect how well your audience can interpret and apply complex information.