Another factor that can have important implications for a map design's success is the final media in which the map will be displayed. Maps can be designed for and produced in a variety of media, though we can classify them into two major types: print and electronic media. Maps created for each type of media have different design problems. In this section, we will focus on design constraints that relate to color and resolution.
Maps designed for print media are also known as 'hard copy' maps. Although the general category of print media can include many types of physical substances that maps are printed or otherwise transferred onto, most hard copy maps are produced with either paper or a synthetic material (e.g., plastic) and ink or toner. When you are designing your map, you may need to decide what type of paper to use, or, if your map is part of a larger report or publication, the publication designer may make this choice for you. Some common paper types include newsprint, uncoated offset stock (e.g., paper similar to that used in your photocopier), or glossy papers that are coated with a chemical treatment (e.g., the paper used to print magazines or coffee-table type books). Knowing what type of paper you will be using is important because different types of paper absorb different amounts of ink, so the final color the map reader sees may look different if the same map (using the same color specifications) is printed on different types of paper. For example, uncoated offset stock absorbs more ink than does glossy paper, so a given color will probably have a softer, more subdued appearance when it's printed on the uncoated paper. Price may also be a concern: uncoated papers are generally cheaper than coated papers. If you are creating a map that might be used under adverse weather conditions, and you are worried about the map getting wet, you might consider using a synthetic material. Some common brands include Hop-Syn, PolyArt, and Tyvek. These synthetic materials are typically some type of plastic polymer and are both waterproof and tear resistant. However, they are significantly more expensive than regular papers, and not every printer is able to print with this type of material. Color appearance varies between types of synthetic materials as well, so if you plan to print with a synthetic, it's important to carefully research the characteristics of the particular material you have chosen to use. Other types of 'hard copy' maps include maps printed on transparencies and maps printed to slide film.
Some advantages on choosing a 'hard copy' format include:
- They are portable, and you can hold them in your hand.
- They can be created with a variety of production technologies.
- They can be printed at very high resolution (see Part VII: Print / Display Resolution for a more detailed discussion of this).
Some disadvantages of choosing a 'hard copy' format are:
- Each copy of a map costs about the same amount to make.
- Some reproduction techniques can lead to a loss in image quality (e.g. photocopying).
Maps created for electronic media are also known as 'soft copy' maps. Some authors have also called them temporary maps (Robinson et al. 1996) or virtual maps. Although the maps are typically stored on a physical substrate (e.g., a computer hard-disk or memory), they must be translated into a visual image with another device, such as a traditional CRT (cathode ray tube) computer monitor, an LCD (liquid crystal display) screen (e.g. a laptop monitor or flat panel display), a computer projector, or a television. Many 'soft copy' maps, such as those created with internet mapping sites, are ephemeral and last only a few minutes. 'Soft copy' maps can be stored using several different types of file formats. Some examples include: JPEG, GIF, TIFF, PDF, PNG, EPS, BMP, and EMF. We will discuss these file types and their characteristics in more detail in Part VIII: Exporting a Map.
Some advantages of choosing a 'soft copy' format include:
- Map reproduction costs are very low (usually much lower than the cost of creating the original design).
- Maps can be created "on-demand." An excellent example of this is the National Map Viewer, an application created by the USGS as part of its topographic map modernization program. If the area a map reader wants to focus on was previously at the intersection of four topographic quadrangles, s/he can specify the map area s/he wants to print or download and does not have to download or purchase four map sheets.
- Everyone can be a map-maker (if not a cartographer!) using internet map servers.
- Because map reproduction costs are low, maps can be updated more frequently, and at a lower cost.
Some disadvantages of choosing a 'soft copy' format include:
- If the map reader wants to print a copy of the map, the cartographer may have exported the map at a very low resolution to promote easier electronic dissemination (see Part VII: Print / Display Resolution for more about this topic).
- The amount of time map readers are willing to spend reading a map may be shorter (especially in the context of internet maps).
- Different map readers will have different monitor and printer settings, so the map you create on your computer may not look the same to the final map readers.
- Using an internet map server to make a map may have limited cartographic controls.
- They require an electronic device for viewing (although portability is becoming less of an issue with the increasing use of smartphones and tablets).
Two important factors that impose constraints on designing maps for different media are resolution and color. Typically, when you are working with print media, you will have the advantage of having a much higher output resolution, which will allow you to use smaller type, line widths, and symbols. Although you can create 'soft copy' maps at high resolutions, computer monitors can only display images at a resolution of 72 dpi (much lower than a typical offset press resolution of 12,000 dpi). We will look at examples of how reducing the resolution can result in poor image quality and readability if a map is not redesigned for a lower resolution in Part VII: Print / Display Resolution.
Specifying colors can be tricky when you are designing for multiple media. This is due largely to how different media produce the impression of color and how our visual perceptual system 'sees' that color. The colors that we see in print media maps are a result of the wavelengths of light that are reflected from (i.e., not absorbed by) the printed page. We typically use the CYMK color model (which specifies a percent of each of four inks to place on a page) to define colors for print media. The colors we see in electronic media are a result of the wavelengths of light that are emitted by the light source (e.g., the electron gun in a CRT monitor or television). We typically use the RGB color model (which specifies an intensity of three colors of light) to define colors for electronic media. Although we will go into more detail about these two systems of creating color in Part IX: Color Spaces and Color Specifications, an important point from a design standpoint is that not all of the same colors can be created with each color model. Hence, if you design your map for print media, using the CMYK system, and then translate those colors into RGB, they may not look the same in both the printed and electronic maps. For this reason, it is very important to test your colors in the final medium/a that you plan to use to avoid nasty surprises.
A second problem you may encounter when working with color and map production relates to designing a map in color and then reproducing it in black-and-white. This may occur in a print media context (e.g., when a color map gets photocopied on a black-and-white photocopier), or an electronic media context (e.g., when a map designed in color for display on the Internet gets viewed by a map reader with a web-enabled cell phone that only has a monochrome display). If you know that your color map may become reproduced in black-and-white, you may choose to adjust your color design so that important features do not become lost in the translation, or create a separate black-and-white version of the map [see Figure 1.5.1].
If you are interested in investigating this subject further, I recommend the following:
- MacEachren, Alan M. (1994). Some Truth with Maps: A Primer on Symbolization and design. Washington D.C.: Association of American Geographers, p. 101-112.