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(For more resources on OmniGraffle, see here.)
Diagramming is really communication. There is a substantial field of study out there, which only deals with the psychology of communication. It is outside the scope of this article to go into the theoretical background on the best way of visually presenting an idea (consider, as an example, some of the works of Edward Tufte). What you will learn in this section are a few handy tips that you may or may not follow. If you decide to follow these tips, your visual diagramming will not go wrong.
However, do not follow these tips as "rules". Obey them if they make sense and disobey them when they get in your way. Most importantly, don't lose sight of, or forget what you want to communicate with your diagram.
Tip 1: Do some planning before you start
OmniGraffle may be the best diagramming tool on the Macintosh. Complex diagrams are still a lot of (hard) work to get right, even with the aid of a computer. OmniGraffle is still just a diagramming tool—it will not do your thinking processes for you.
For small and simple diagrams where you have full knowledge of what you want to communicate, you can start working directly in OmniGraffle. However, for bigger and more complex diagrams, it may be easier to start your thought process using a white board, or some paper and a pencil.
If you still insist on using a computer for organizing your thought processes, you should take a look at OmniOutliner from the same people that make OmniGraffle. The cool thing about using OmniOutliner is that you can import your outliner documents into OmniGraffle and then OmniGraffle will create a diagram for you.
If outlining is too simple, and you are more used to mind mapping—there are some simple mind mapping stencils at Graffletopia. However, you may be better off using a specialty tool like MindManager from MindJet Corporation (http://www.mindjet.com/).
A very good example of planning ahead is traffic signs. Designing traffic signs takes into account the driver's needs and requirements (that is, easy to understand pictograms going by in 120 km/h on the highway). These signs may seem simple to create – but a lot of work has been put into them to make them this simple. Even if you have not seen a given sign before, there is a good chance that you will understand it's meaning without further explanation.
A good diagram should be like a well designed traffic sign.
Tip 2: Colorize gently
The old adage that "less is more" really applies to diagramming at large.
Use light colors whenever possible when filling shapes. Try not to mix strong and light colors on the same diagram.
If want to use text in colored shapes – take into account the contrast of the background color and the text. Light colors should have black text, and strong colors should have white text. Stick to either black or white text.
Use as few colors as possible – never use yet-another-color just because you can.
If you need ideas on which colors may match each other you should investigate the software tools found on the ColorJack website (http://www.colorjack.com/). The ColorSphere and the swatches are a good starting point.
Another interesting website to get some ideas on good color combinations is the Kuler community. In this community users are both sharing their own color swatches, and can vote on the best-looking color swatches in the community. You find Kuler community at http://kuler.adobe.com/.
If you need to use colored text on a colored background – and really care about the readability (contrast) of your message (which you should), then you should try the Colour Contrast Check tool from snook.ca —go to http://www.snook.ca/technical/colour_contrast/colour.html and experiment with foreground and background colors.
Tip 3: Use few fonts
The rule of thumb to use on any publication with regards to font use: Never use more than two fonts.
Unless for the title of your diagram, avoid using serif fonts. Serif fonts have small details on the end of each stroke making up a letter. A very good example of a serif font is Times Roman.
The text you are reading right now is set in a serif font. The various headings found throughout this book are without serifs. These fonts without serifs are also known as sans serif fonts.
Good diagramming fonts are Helvetica, Futura, Optima, and Lucida Grande. All these fonts are sans serif fonts, and readily available from the Fonts stencil found in the Common stencil directory. This said, if your main document is not using any of these fonts—try to match your diagram fonts with your main document.
Though one of the "rules of thumb" regarding fonts and types is not to use ALL CAPS, there may be times when it is appropriate for your diagram. The same also is true regarding starting a word with an upper case letter. It may look better to start a word using lower case.
Tip 4: Consider your output media
If your diagram is going to appear in a printed report, thin lines may be better than thicker lines.
If your diagram is going to appear on a wall poster—thicker lines will probably be better than thinner lines as the reader is reading the poster from a distance.
If your diagram is going to appear only on screen, thicker lines may be better than thinner lines, but try not to go beyond 2 points thickness.
A thin line is a 1 point thick line—a thicker line is 2 points or more.
Tip 5: Symmetry is better than asymmetry
By nature, our brains tend to seek symmetry. Symmetry helps your diagram look balanced. Balance makes your diagram look more professional.
There is a caveat regarding visual symmetry: Visual symmetry does not equal mathematical symmetry. A good example of mathematical symmetry is the income diagram shown below.
The cylinders below the blue arrows are mathematically correct but if you study the diagram you might get a nagging feeling that there is something not quite right. However, you cannot really put your finger on what the problem is. This is probably due to the lack of visual symmetry. One solution is given below where the expenditures are alone shown in cylinders. The saving is shown as a piggy bank using a stencil called Cash Flow from Graffletopia.
Any educated graphics designer (architect, photographer, illustrator, and so on) will tell you that you should favor visual symmetry rather than mathematical. If you are unsure about how to do this—just create diagrams that "feel and look right". If this fails, go down the mathematical symmetry route.
Tip 6: Have one, and only one, focus point
The focus point is the most important part of your diagram.
Creating diagrams means that you will have several elements in your diagram. If you are not careful, your readers will not "get" your diagram without spending a lot of time studying the details. It is really important to have as few focus points as possible. If you can get away with only one focus point – this is excellent. If your number of focus points increases beyond five, your diagram runs the risk of becoming everything and the kitchen sink – as such, you should really go back to your planning stage!
If your diagram is conveying more than one message, try to make more than one diagram. Even if your audience is versed in the subject it will often pay to either divide the diagram – or create separate ones.
Tip 7: Apply the Golden Ratio to stand alone diagrams
If your diagram is not part of an accompanying and explanatory text, you should apply the so-called Golden Ratio. Another name for the Golden Ratio, is the Rule of Thirds. In practise you divide your page into thirds, both horizontally and vertically. You will now have a grid of nine boxes. However, it's where the horizontal and vertical lines cross each other that you should concentrate. This is the part of your diagram where you should place the most important elements.
Tip 8: Use titles, figure captions, and legends
Stand-alone diagrams must always have a title telling the reader what the diagram is about.
If your diagram is part of a book or a report, you may want to include figure captions – at least if you reference your diagram at more than one place in the text. Instead of addressing the diagrams as "In the second diagram from the bottom on page 34, we see that ..." – put a figure caption below the diagram, and you can now address the diagram in the text as "In fig. 12, we see that ...".
If your diagram contains elements that may not be intuitive for the reader, then add a legend to your drawing. If the lines between elements have different colors—then you absolutely need a legend to explain the difference between the red and the green lines.
It may be an excellent idea to place the legend inside a box a bit away from the diagram with a readable heading stating: Diagram legend.
Tip 9: Be liberal with white space
Use space around your elements. Do not cramp them together, as this will make your diagram look messy and dirty.
It's better to use a whole extra page in landscape mode in a report for an important diagram, rather to compress the diagram to fit within the text.
In the planning stage of your diagram, take white space into account – and you may end up with a different layout that is more fitting for your report than your original plan.
A lot of times your diagram will end up in a report or on a web page. Most of these places adhere to portrait-based layouts. It may be a good thing trying to make your diagram fit a portrait-based layout – rather than sticking to using landscape out of habit.
Tip 10: Be consistent
Never use two different shapes for the same kind of element.
Never use two different colors on shapes or lines to convey the same meaning.
Never use different fonts, and font sizes, within the same types of shapes.
Let's say you need to have a diagram involving animals in the general sense. If you can't find a drawing or a picture of a group of animals – use the same animal concisely. Also, use a shape/picture/drawing (animal) that people recognize.
Best practices give diagrams which will communicate the intent better.
- OmniGraffle 5: Making your Diagram Look Good
- OmniGraffle 5: Shape Selection, Re-Styling and Color Picker in Detail