# Levels of Geographic Abstraction LLMS index: [llms.txt](/dvw/en/llms.txt) --- Geographers have many different ways to look at this and other real worlds. They’re experts, after all. Most players of virtual worlds are not geographers, however, and they’re only going to notice more obvious errors. A degree of knowledge beyond that of the average player is always a good thing for a designer to have, of course, but as soon as players stop noticing what you’re doing you can stop. Immersion is about not busting players into reality; it isn’t about teaching them erosion patterns for sedimentary rocks [^25]. From this point of view, the levels of abstraction listed in the previous section are sufficient to give a virtual world all the geographic consistency it needs. Let’s look at them in more detail. Zones are a functional partition of the virtual world, imposed for technical reasons. Not all virtual worlds will have them. Their usual impact is to consolidate geographical features into zone-friendly blocks. The mountain range will stop short of a zone boundary, rather than poke a couple of foothills across it; the river will run through a zone, but not weave over zone boundaries and back; the peninsula will jut out just far enough that it won’t entail a zone change to reach the end of it. Zones are like the pages in a road atlas, except that you get to change the geographic features so they’re a tidy fit. Regions are large swathes of territory that have distinct, thematic differences at the strategic level. “The north,” for example, may be cold, populated by hardy, hairy, expansionist barbarians; “the isles” may be beautiful, lazy paradises whose inhabitants have a penchant for human sacrifice; “Westside” may be a neighborhood full of big houses with pools and long driveways, populated by rich people who have nothing but contempt for those born across the river. Regions fit natural geographic boundaries. If they spill across such a boundary, it’s a cause for conflict. In worlds that have zones, the two often coincide; this is because players feel zone boundaries with the same (if not more) intensity that they feel purely geographical ones. The zone/region relationship is not necessarily one-to-one—you can have several zones to a region or several regions to a zone—but it’s usually integral; you won’t find 1-region zones very often. Areas are subdivisions of regions that, while thematically similar at the strategic level, are thematically distinct at the tactical level. “The north” may consist of “the mountains,” “the valleys,” “the frozen waste,” “the isle of the gods,” “the lava pits,” and so on. It’s often the case that areas are specified fully by individual designers, to ensure an atmospheric consistency within each area. Areas are made up of rooms. This is the level at which players experience the virtual world. The definition of what constitutes a “room” depends on the way the virtual world is displayed to players. The options are - Nodes - Co-ordinates (tiles) - Co-ordinates (polygons) Nodes are points with (potentially) unlimited connections to other points. These are the dominant paradigm for textual virtual worlds, although some also use co-ordinate systems. Normally, a single node represents the smallest unit of position that players can share, which (in buildings) would be a room—hence the name. Formally, tiled co-ordinates are nodal systems that enforce a rigid relationship between the nodes; you can, in theory, represent them as freeform nodes. In practice, though, tessellation is used because it can be implemented easily with an array. There are often other contributory reasons, but its mapping to a fast, random-access data structure is the main one. Arrays allow for automatic content generation for speedy, shortest-route path-finding and (most importantly) for display as (2D) graphics. Textual virtual worlds that use tiled co-ordinates will usually give the tiles the same status as other nodes—that is, treat each as a room that more than one player can potentially occupy. Graphical virtual worlds go for a smaller granularity, with a tile representing the space that an individual character takes up; for this reason, they are single-occupancy only, and a subjective “room” consists of contiguous tiles bordered by ones that contain walls, doors, windows, and other architectural features. Both the nodal and tiled approaches define a virtual world in terms of space. Polygons define it in terms of enclosures. Characters do occupy co-ordinates, but their world is defined in terms of barriers—planes through which they cannot move. As an analogy, consider a piece of graph paper: Nodes define the lines by numbering the squares; polygons define the squares by numbering the lines. Virtual worlds that use co-ordinate systems can be displayed graphically. The resolution of the co-ordinates in a polygonal system is yet smaller than that in a tiled system, because characters themselves are made up of polygons. The concept of a “room” still exists, as an enclosed space that many characters can occupy, but it’s not atomic: Characters can be between rooms, in some kind of transition state; for a nodal system this location would itself constitute a room. Of the three, a tessellated system is the least flexible. It doesn’t have the resolution to handle details; in particular, it doesn’t get along well with curves. Carefully drawn texture maps can create illusions of curves, but they’re exposed if players ever do anything to them (for example, walk on what looks like a gentle curve but is actually a step). When 2D is used, it’s normally because it’s relatively easy to implement, to animate [^26], and to upgrade [^27]; it’s often the first choice for hobbyist virtual worlds such as Furcadia [^28]. This may change as cheap or free full 3D engines become more available [^29], but some people prefer the “pieces on a board” look and the clear demarcations of space it offers; the 2D approach is therefore unlikely to go away. A world made of polygonal planes better represents different facets of an environment, because of its higher level of detail. You can easily rotate large objects through arbitrary angles, not just 90 degrees. Curves still have angles, but these are small enough to hide behind texture maps without looking fake [^30]. Node-based systems are the most flexible of all, because they allow for non-Euclidian geometry. In a nodal world, you can exit a room to the north to enter it from the east; you can walk into a wardrobe and find Narnia there; you can be inside a room that contains itself; you can have multiple exits leading to the same entrance; you can reconnect or destroy nodes, leaving a sealed void. The most immediate benefit of a nodal approach is that you don’t have to use a constant scale. A journey to the top floor of a tower can take as long as the journey across a mountain range. Important details can thus be given close attention, whereas unimportant ones can be dismissed as part of a broad sweep. The world can focus on what matters, matching the way that a cognitive map built up in a player’s mind works. Worlds founded on a co-ordinate system are limited to real-world physics, and don’t have this level of refinement. On the other hand, they can be represented graphically, which can’t be said of an unrestricted nodal system. An issue affecting all these approaches is what to do at their edges. If you keep walking east what happens? There are a number of tried-and-trusted ways to deal with this situation: - Wrap around. If you go east forever, you end up back where you started—just like with the real world. - Physical boundary. There’s an unclimbable cliff, unswimmable river, unnavigable ocean, impassable forest in the way. - Big stick. If you walk too far into the desert, the sun is going to bake you dead no matter how well-prepared you thought you were. - Emotional boundary. Your character “doesn’t want” to go any further. You might, but you don’t control your character. - Notice. If you try to go too far, you’re given a polite message explaining that the designers have failed to provide the necessary content. - Invisible wall. There’s no explanation, you just can’t move off the board. Of these, the physical boundary is the most popular as it’s within the context of the virtual world and leaves open the door to further expansion. Unfortunately, it’s so popular that its expression can lead to cliché. “Hmm, the sea. Looks like I’ve reached the western edge of the map, then.” There is a great opportunity for imaginative solutions here. [^25]: I guess this statement wouldn’t apply to a geology-focused educational virtual world, though. [^26]: Assuming some degree of artistic talent. [^27]: Updating animations can, however, be more expensive than for a 3D approach. [^28]: http://www.furcadia.com [^29]: Ultima Online now boasts both a 2D and a 3D client for its virtual world. [^30]: There are limits, though. In a demonstration of a new role-playing game at a computer show, I found I could hide my character completely in the texture map of a tree that overflowed the space that the tree formally occupied. Great for ambushes!