Well-designed maps use variations in the three color variables in ways that reflect the kinds of variations in the underlying data they represent. Cartographers also need to simplify the features on a map beyond the tasks of feature type selection and feature classification in order to make a map more intelligible. Finally, users make decisions and take action based upon what they find in the map. These methods may be combined. The John A. Dutton e-Education Institute is the learning design unit of the College of Earth and Mineral Sciences at The Pennsylvania State University. In the process of deleting entities, imagine creating a map of cities for the United States. This is the topic we discuss next. There are many kinds of data classification used on maps; we will focus specifically on classification of numerical map data in more detail later on in the chapter. requirements to start the next sta ge, the pre-fieldwork compilation. The map in Figure 3.5 shows how a cartographer selected specific highways to include along with a few other features; these other features include a very generalized representation of the terrain, a few major rivers and lakes, and an indication of the area included in each of several communities (in pastel colors). This sequential scheme aligns colors from light (depicting low data values) to dark (depicting high data values) in a step-wise sequence. The color schemes have been tested with users who have color deficiency (about 8% of the population; difficulty distinguishing red from green is the most common). The objective is to help drivers pick efficient routes by depicting the highways and whether traffic is moving quickly (green) or stalled (red). The BSP tool is the one that actually converts the .vmf file data into a usable .bsp file that the game engine can load. This tool is normally the one responsible for slowing down compiles most of the time as it has to process huge amounts of data in the completion of its task. We call these primitives graphic variables because each represents a “graphic” (visible) feature of a map symbol that can be “varied.” While different cartographers have identified a slightly different set of primitives, most agree that there are somewhere between 7 and 12 of them from which all maps symbolization can be constructed. As you can see above, three of the graphic variables are components of color. As you zoom out to a smaller scale, you will view the various smaller streams of the Susquehanna begin to collapse into a single blue line as the details of the river aggregate. In this case, if the purpose was to show the most populous cities, a fixed population threshold produces a very appropriate result. Depending on the purpose and nature of the map, a map montage model is made, and the scale, cartographic projection, and cartographic methods of representation and symbols are chosen. Figure 3.9: Screenshot of a single hue sequential color scheme for 5 classes (left) and a multi-hue sequential color scheme for 5 classes (right). Two contrasting dark hues converge in color lightness at the critical value. This simplistic event hides a more complex set of operations taking place out of sight of the user. As long as you understand what the tools are used for, that should suffice. As Phillip Muehrcke (an Emeritus Professor of Geography from the University of Wisconsin) details, the cartographer must answer four questions: Where? In analyzing the current trends toward improving map production a number of basic directions may be identified: the development of techniques for compiling and preparing maps for publication; mechanization of photocomposition; introduction of microfilming, electrophotography, and photoluminescence; improvement of photocopying operations; automation of computing and constructing the mathematical base of the map with computers and the automatic coordinatograph; and automation of the preparation of publishing originals and the process of generalization. The table that follows should give you a good idea of what each tool does. Well that's what I'm here to explain. The drawing may be composite (all hachures entered on one copy), partially separated (one element of the map drawn on one copy and the rest on a second copy), or completely separate (individual publishing originals prepared for each hachure element). Figure 3.12: Screenshot of a qualitative color scheme for 5 classes. Deliberate exaggeration of map features is often performed in order to allow certain features to be seen. This article should be converted to third person to conform to wiki standards. Map makers must delete, for instance, cities below a certain population (as done in the map on the right) in order to better serve the purpose of the map. This includes choosing to delete, smooth, typify, and aggregate entities within feature types. In the final process of creating a map, the cartographer symbolizes the selected features on a map. As an example (Figure 3.5), a cartographer can create a map of San Diego (where) showing current (when) traffic patterns (what) so that an ambulance can take the fastest route to an emergency (why). The following chart shows the overall process required to create a playable map file (.bsp). The cartographic process is a cycle that begins with a real or imagined environment. They do not create finished maps. Editorial and preparatory work includes collecting, systematizing, studying, and scientifically collating cartographic source material. The visibility map above is a good example of typification in which the actual geographic shape of state boundaries is replaced with what might be considered a caricature that retains only key aspects of each state’s shape.