Geographic Information System/Map Elements
The title of a map should be dominant in size and is typically the largest text on a map. A good map title should focus the user's attention on the purpose of the map. A good map title should also be brief but descriptive. Typically, a map title will include information such as where the map is focused, what information is being focused upon, and the timeframe for which the map is applicable. Map titles are typically placed at the top center of the production medium, however a map title can truly be placed anywhere so long as it is easily found by the map user. If the map is a figure in a larger document, you should not place the title on the map, but instead, place the title of the map in the caption.
- Dominant in size
- Focuses attention on map purpose
- Brevity is desired
- Typically includes where, what, and when
- May omit if figure and caption exists
The map body is the main focus of the map and contains the geographic featues that are important to the message of the map. The map body is typically the largest map element on the map, and should dominate the user's attention.
Typically, when designing a layout, the map body is placed first, and other elements are then placed around. However, do not be afraid to move or resize the map body to better accommodate other elements. Being that the map body is the element we want the user to focus on, it should be easy to find, dominant, and of adequate size to effectively show the geospatial data.
(image of map)
Inset maps are small ancillary maps that have a larger scale than the main map body. The role of an inset map is to show more detail in a map body of a smaller geographic area.
In the example provided, the United States of America is the main map body, and the smaller map of Arkansas in the lower right-hand corner, is the inset map which is showing a smaller area in more detail. To make it obvious to the map reader where the inset map is referring to on the main map, you should show an outline of the extents of the inset map on the main map body, or provide leader lines from the main map body to the inset map.
(image depicting details previously described)
A location map is a small ancillary map that is at a smaller scale than the map body. The location map identifies a location of where the main map body is in a larger geographic context. A location map is to be used when the location of an area on the main map body is unfamiliar or not intuitive to the map reader. In this illustration, the map of Arkansas is the main map body, and the smaller map of the lower right-hand corner is the location map. Similar to the inset map, there is a visual marker on the inset map that shows the map reader where the main map body is located.
(image depicting details previously described)
The map scale is used to measure linear relationships on the map. A map scale is typically included on a reference map, but is not required to be included on thematic maps. A map scale should only be included on a map when you want the user to measure the distance on the map, or the scale of the map is not intuitive to the map reader. There are three types of scales that we can place on a map:
- representative fraction
The graphic scale is perhaps the most common type of scale placed on maps. The graphic scale is a visual representation of the ratio at which the Earth has been reduced. The graphic scale typically starts at zero, and measures out to a meaningful, typically round number. One major advantage of a graphic scale is that if the map is enlarged or reduced, say using a phorocopier, then the graphic scale will scale with the enlargement or reduction, and will always be correct.
(image depicting map with graphic scalebar)
The verbal scale is a statement that describes how a distance measured on the map relates to a distance measured on the ground. Again, it is important to use meaningful, typically round measurement units to make it easier for the map user to measure distances..
Example: Verbal Scale
One inch on the map equals twenty feet on the ground
Representative Fraction Scale
Sometimes referred to as the unit scale, the representative fraction scale is a map scale that is used to represent units in centimeters, inches, or feet in the form of a fraction or a ratio. This fraction or ratio, 1:x is used to indicate one unit on the map. The number to the left of the colon indicates that one unit on the map represents x units on the Earth's surface indicated by the number to the right of the colon.
Example: Representative Fraction Scale
The legend element identifies unknown or unique map features succinctly. A legend may optionally have a title, or contain the title of the entire map. The legend needs to have representative symbols that are found on the map followed by a description of what each symbol represents.
The symbols on a legend sould be the exact same color, shape, and size of the symbols shown on the map. If the symbol on the map vaires in size, the symbol in the legend should be the size of an average sized symbol on the map.
General Reference Map
For a general reference map legend, it would display all symbols found on the map. The representative symbol should be to the left of the short description, and the legend can be organized vertically in one or more columns.
(image depicting symbols with text descriptors)
For a thematic map and in this case a graduated symbol map, the graduated circle legend is to show how the size of the symbol changes with the value of the attribute that it is representing. Graduated symbol legends can be placed in a vertical layout, horizontal layout, or a nested layout.
(image depicting graduated symbol legends, vertical , nested and/or horizontal)
The directional indicator is often considered part of a legend, and may be placed inside the neat line around the legend, near the legend, or elsewhere on a map.
The directional indicator, commonly a north arrow, is necessary when north is not at the top of the map, or the map readers are unfamiliar with the area being displayed on the map.
(image of a map direction indicator)
Labels communicate attribute or ancillary information directly on the map body, and related to map features on the map body. The purpose of a label is to identify features on the map, and help users to orient themselves to the information being displayed on the map. Labels should be placed at locations that allow the map reader to easily associate each label with the feature it is labeling, and should be reasonable in size.
(image showing several map labels)
Metadata or credits are used to cite the sources of data sets used to create a map. It is also used to map author's information, the date the map was created, and other explanatory information about the creation of the map. Since you want the user's focus to be on other aspects of the map, metadata should not be visually dominating.
Metadata is generally placed along a bottom edge of the map and deemphasized. If the map reader wants to read the metadata, they will typically spend a little time searching for it.
Metadata (Credits/Attribution) are used to:
- Cite the sources of data sets used to create a map
- Provide the map author's information
- Include the date the map was created
- Include any additional information needed
The graticule visually represents a coordinate system or location scheme. You should include the graticule on a map if the map reader will be referencing coordinate locations throughout the map.
You should use meaningful divisions on the graticule so that it is easy for the map reader to use it. Typically, graticules are omitted from thematic maps as the purpose of a thematic map is not to measure, but to look at spatial distributions and patterns of data.
(image of map with graticule)
The neatline is considered to be the frame of the map and should encapsulate the map and map elements if needed. The goal of the neatline is to provide a nice, clean frame for the map to live within, and to separate the map from surrounding items on the medium. The neatline is used to direct the user's eyes to the center of the map. Generally, neatlines should not be visually dominant, but large enough so that the eye can use it as a frame.
(image of map with neatline)
Ancillary text and/or objects are additional supporting information which provides a greater understanding of the topic of the map. A few examples of ancillary text or objects are:
A couple of common reasons to include ancillary text on a map are to indicate data manipulation pertinent to the interpretation of the map and indicate special cases or missing data.
Ancillary text and objects are used to:
- Provide a greater understanding of the topic of the map
- Help with the interpretation of the map
- Highlight special cases or missing data
Best practices dictate that map elements are positioned and sized in accordance with their importance. The most significant items should be roughly at the center of the map or placed at thte top of the page. This is typically why the title is set at the top of the page, and the map body is in the center of the page.
Map elements should use as much space as possible within the neatline so that white space is reduced. Additionally, the map elements should be placed around the map, so that the map has a visual balance that is pleasing to the eye.
Map elements should be:
- Positioned and sized based on their importance
- Used to reduce white space
- Balance the map layout