The two forms of grouping levels most commonly seen are the categorical group (e.g., all land-use colors placed separately from all stream-level colors) and the shape-type group (e.g., all polygon features placed separately from all line features). Use headings to describe each group in categorically separated legends, if your organization schema is not immediately obvious. When categorical separations are not needed, shape-type groupings are often displayed in the following order: points, lines, polygons. Other times they are displayed in the order of relevance to the overall map purpose.
Default legends produced in the GIS are a great way to begin production of the legend but ought to be further manipulated prior to map publication. First of all, make sure there isn’t too much space between the items and their labels. Also, if the legend is describing a gradient of values (choropleth color scheme), then those items will look more professional if they are touching each other rather than separated by white space. Don’t forget that color gradients can be depicted vertically (Figure 3.4) or horizontally (Figure 3.5).
A label can still be associated with each item, although in many cases we can do without the intermediates and label only the maximum and minimum values. Creative color gradient legends could also employ other effects such as dials (e.g., speedometer-type dials) or graphs (e.g., elevations and colors).
FIGURE 3.4
Color gradients depicted vertically.
FIGURE 3.5
Color gradients depicted horizontally.