CityCraft: Suggesting size and complexity

Imagine you’ve completely planned and detailed a unique, sprawling metropolis. Your imaginary city is meticulously mapped, thoroughly described, and its architectural styles have all been sorted out. You’re proud of your creation, even if attempting to digitally model it in its complete glory would probably cost you a few million pounds. It is, you see, no mystery why even the grandest Grand Theft Auto metropolis is tiny when compared to a modestly sized, real life urban centre.

Assuming you’re neither Blizzard nor Rockstar, you’ll have to think carefully before building your virtual city. You’ll have to abstract and generalise your world, probably limit exploration to a handful of locations, or avoid creating an open world altogether. You’ll have to imply a sense of history and life in as cost-effective a way as possible, and somehow convey a scale that isn’t really there. So how can we do this?

A thousand words

If a game’s design allows for it, we can do amazing things with little more than a single image – a view through a window or a 2D background, for example. Provided the appropriate elements and detail are there (see Figure 1), scale can be conjured up with relative ease. Dense apartment buildings, hundreds of washing lines, and a background of churches, chimneys and obvious population density simply couldn’t exist in a village or a small town – such a view could only be found in the middle of a city.

Figure 1: Early 20th century tenement houses. Notice how a simple static image instantly creates a sense of scale

Only a tiny part of such a place needs to be shown, and people will instantly, almost instinctively, identify this type of density, architecture and spatial organisation as decidedly urban. What’s more, an image like Figure 1 provides the viewer with a hint of a city’s overall texture and history.

Practically, this means that small urban scenes in carefully selected areas can also work brilliantly in implying size, complexity and texture, and they’ll allow us to conjure images of everyday life. They can showcase our elaborately thought-out creation in an easy to summarise way – provided, of course, there is a sensible backstory to our city, and an imaginary or real geography to draw on. Using a pre-existing city plan (or actual city) for inspiration can help immensely here.

Wadjet Eye Games’ Blackwell series (see Figure 2) was particularly successful in evoking the richness and sheer size of New York, and distilling it all in low resolution, two-dimensional images. Picking which elements to show – a huge bridge that only a major metropolis could ever afford to build, a jazz musician or the silhouette of a skyline – is crucial in capturing New York’s ambience. Snapshots of infrastructure, such as bridges and roads, are another means of instantly creating a sense of scale.

Figure 2: A bridge, a saxophone and a highly abstracted skyline by the river are more than enough to set a scene in 1970s New York

Sound and space

A carefully designed soundscape can suggest a much larger virtual city than the one players can see. Blaring sirens in the background, dogs barking in the distance, the roar of unseen traffic, underground subway vibrations, and distant church bells can easily expand the perceived game space. Best of all, sound is much cheaper to create than a vast city map.

Buildings and maps

Movies, by using sets and carefully framed shots, have long been able to create the illusion of much larger places. Director John Carpenter’s classic In the Mouth of Madness, for example, created an urban area by showing seven buildings arranged to look like a stereotypical Main Street in America. It was the topology of those buildings that created the sense of structure, and it is clever placement and topology that game designers can employ to create a similar illusion themselves – as shown in Figure 3.

Figure 3: Four different ways of arranging seven buildings; four different settlement patterns.

There’s also the option of providing players with in-game maps that fill in the detail a city is missing. The combination of a few carefully selected views, a selection of maps strategically placed in the game world, and a dominant landmark shown from a variety of distances worked wonders for City 17 in Half-Life 2. The Final Fantasy series’ Midgar, on the other hand, only allowed players to visit a dozen or so locations, but used cutscenes to show the city from afar, or a wireframe map to establish scale.

Strategic roadblocks

Blocking views is another handy trick in the virtual urbanist’s arsenal. When looking to create, say, long avenues or boulevards, you should avoid designing straight roads; even more so if they would allow a view to the horizon or past the city limits. Curving your avenues will obscure their short length, hide unwanted views or unmodelled areas, and suggest a denser, richer urban environment (see Figure 4). Similarly, mountains of tall buildings may obstruct the view of the suburbs, and medieval fortifications will block a player’s line of sight.

Figure 4: Curving roads can successfully hide their short lengths, as well as adjacent empty/unmodelled spaces, while simultaneously saving processing power.

You can also block off whole areas, and treat them as much simpler to craft backgrounds that can never be visited. Most of BioShock’s Rapture was seen exclusively from afar with malfunctioning bulkheads believably restricting access, and Grim Fandango hid most of El Marrow behind a colourful yet impassable carnival.

There are obviously countless other ways of blocking off areas, just as there are dozens of other tricks that can be applied to misdirect a gamer’s eye. Modelling a city block that in reality contains 16 buildings using only eight will easily go unnoticed, while sending players through sewers or subways will help expand a perceived space. And, of course, the interiors of most buildings don’t have to be modelled, as we don’t expect to enter every building we see in real life, either. With a bit of cunning and a lot of planning, then, you too can create the impression of a gigantic, bustling city.

Modularity and procedural generation

Two oft-employed methods to help reduce the work of creating large settings are modular design and procedural generation. Breaking buildings and infrastructure into flexible, repeatable elements (door, walls, roofs, windows, concrete tiles, etc.) allows for huge gains in speed and reductions in asset-building costs. Procedural content, on the other hand, especially when touched up by hand or shown from afar, can rapidly and cheaply create a convincing cityscape.

More features from Wireframe magazine