Tutorial: Harnessing the Power of Illustrator’s “Symbols” Feature in Transit Map Design
Imagine this scenario: you’ve been working for months on a complex transit map — lots of interchanges and routes — for a big-city transit agency and you’re presenting it to their management team for approval. They love it, except they’d like the circular interchange markers you’ve used to be square with rounded edges instead. And they’d like to see the revised version in an hour.
If you’ve used standard Illustrator artwork for each of your interchanges, then you’ve got a frantic afternoon of finding, deleting and replacing every interchange marker on the map ahead of you. However, if you’d used Illustrator’s Symbols feature, then this request would be an absolute breeze.
Symbols were quietly introduced into Illustrator way back when Adobe acquired Macromedia, and are a feature lifted directly from Flash. Put simply, the feature allows you to define Illustrator artwork as a “symbol”: every duplicate of that symbol is linked to that original artwork. Which means that when you edit the symbol’s artwork, it instantly updates all the duplicates (or “instances”, as Adobe likes to call them). Super powerful and not used nearly enough by most.
STEP ONE: Defining a symbol couldn’t be easier, as seem in the first image above. With the Symbols palette open (Window menu > Symbols or Shift-Cmd/Ctrl-F11), simply select your artwork and choose “New Symbol…” or click on the “New Symbol” icon at the bottom of the palette. In the resulting dialog box, give your symbol a descriptive name, and choose a registration point. For an interchange symbol, the centre point is best. If you’re creating a symbol for a “tick” mark, then use a registration point that matches where you’d like the tick to attach to its route line.
Click “OK” and you’re done!
STEP TWO: Picture 2 shows the Symbols palette with three different station marker symbols set up and ready to use. If you are using “ticks” or other markers that are colour-coded to the route lines, you’ll have to make symbols for each colour and variation needed. To make more instances of a symbol, you can drag one out of the Symbols palette onto your artboard, or you can simply duplicate one that already exists. Symbols are readily distinguishable from normal artwork: they have a little bounding box and a little “+” marker that corresponds to the registration point you defined in Step 1. For a symbol where the registration point doesn’t actually align with anything useful, like the double interchange marker, you can still see and use the centre points from the original artwork to align things properly.
STEP THREE: The third picture shows the solution to our problem and the real benefit of using Symbols. I’ve created new artwork for the interchange marker — a square with rounded edges, just as the client requested. With that artwork selected, click on the “Interchange” symbol in the Symbols palette and choose “Redefine Symbol” from the flyout menu. Instantly, every instance of that symbol takes on the new appearance! You can also double-click on any instance of a symbol to edit it, but I find this “Redefine” method easier when completely changing the look of a symbol.