All Good Online Maps
What All Good INTERACTIVE - ONLINE Maps "Should" Have
(from ENVS-418 Computer Cartography)
Note that for web maps created using ArcGIS Online, most of the requirements below are a part of the ArcGIS Online "Web Mapping Application" as opposed to the ArcGIS Online "Web Map." An ArcGIS Online Web Mapping Application is the container that allows a Web Map to be delivered to the general public in an intuitive and useful manner. As such, the Web Mapping Application needs to supply whatever support information is required to use the map properly. For simplicity, these combined Web Map Applications and Web Maps are referred to here as "Online Maps."
The title should be in a large font, easily identifiable as the title of the map and should include descriptive text as to the location and purpose of the map. If the map is thematic, the theme should be included in the title. For example: Corn Production in Washington, 1990. Online maps often have a descriptive sub-title supporting the main title. Sub-titles can also be used for listing the name of the cartographer and/or the organization hosting the map. This Title is often repeated in the About and/or Credits sections.
2. LEGEND / Layer List
A Legend defines the symbols or colors used on the map. Maps (and/or certain map features) do not need legends if the symbology is so common or simple as to be easily understood by the reader. However, it must be clear what each marker or line type, weight and pattern represents. Likewise, having 'pop-ups' associated with the features may lessen the need for a legend. The more complicated the symbology on a map the more important the legend becomes.
Online maps often also have a list of Layers. Optionally, these Layer Lists can allow the user to turn individual layers On / Off (see Interactivity below)
Sometimes the Legend and the Layer List are combined (i.e., a list of layers that can be turned on / off and show symbology for each layer)
Map credits are sometimes combined with an Info / About section. Some of the information can also go in the title or sub-title or can be included in names of the data layers. Regardless, the following information should be included and available somewhere.
- NAME of the CARTOGRAPHER
- NAME of the ORGANIZATION responsible for the map (often including a Logo and/or URL)
- DATE of the MAP creation/publication
- DATE of the map DATA
- SOURCE OF DATA
- SOURCE(S) OF PHOTOS (if photos are used)
4. ABOUT SECTION / Information / Usage Instructions / Help / Statement of Map Purpose
The About section is sometimes provided via a Splash screen when the map is first opened. The About section is sometimes combined with the map Credits. The About section is sometimes labeled Help, Info, Usage, etc.
Unless the entire content and functionality of the map is completely obvious the map should have an easily located About section telling the user what the intention of the map is and how to use the features included. LINKS to data sources used in the map, hosting organizations, sources for more information, or related websites may also be provided. Likewise a Contact link (to the Cartographer and/or their Organization) may be provided. If an online map was created for a class or academic project the project, course name, number and/or instructor should be noted (as part of the purpose / intent of the map)
The most fundamental difference between an online map and a static map is that online maps are interactive. At the very least, almost all online maps should include:
- The ability to PAN and ZOOM the map
- The ability to turn LAYERS ON / OFF
- The ability to click on a feature to obtain more information (typically through an Attribute Pop-Up)
- The ability to print or export the map (or a portion of the map)
In addition, online maps can also include (optional) other interactive tools, such as:
- The ability to change the BASEMAP
- Spatial BOOKMARKS (if there are specific areas of interest the map should provide spatial 'Bookmarks' to assist the user's navigation)
- The ability to change the SYMBOLOGY of the map (colors of features, etc.)
- The ability to ADD DATA layers to the map
- The ability to EDIT DATA layers in the map
- The ability to see one's LOCATION (via a GPS or other location methods) on the map
- The ability to find ADDRESSES on the map
- The ability to perform ROUTING and directions
- Analytical and GEOPROCESSING tools
The choice of which tools or types of interactivity are provided should be driven by the purpose / audience of the map.
Whatever tools or interactivity are provided, they should be clearly explained (both their function and their usage) if they are not completely intuitive. This can be in an About section, in a Splash screen, a Help section or elsewhere. Regardless, it should be easy to find and understand.
6. SCALE INDICATOR
Since the scale of an online map is variable a SCALE INDICATOR is usually included. The scale of an online map is typically indicated by a graphic bar scale.
7. ORIENTATION (Optional)
Most online maps default to North being up. If the map's orientation can be rotated, than a NORTH INDICATOR is required.
8. LOCATOR MAP (INSET) (Optional)
An Inset LOCATOR MAP (also referred to as an Overview map) can be helpful if the area of the map is not easily recognizable or will frequently be used at a large scale (zoomed in).
9. EFFECTIVE GRAPHICAL DESIGN
Layout design is less of a component for online maps than for static maps. Still, the layout / design of the webpage / container for the map remains important. Layout design refers to the planning and decision making processes involved in the visual display of the spatial data. The map and map elements should be:
- Neat and clear
- Without unnecessary clutter (keep it simple, be wary of 'artistic' details)
- Easy to find Credits, About and Help sections.
10. VISUAL HIERARCHY
A hierarchy of symbology should be used for the lettering, line weights and shading. More important features are typically larger and/or darker, less important/background information should be smaller and/or lighter. At the same time, do not "over weight" or "under weight" features. Using scale-dependent symbology and labeling can help in maintaining a usable map at varying scales.
Visual hierarch (i.e., drawing the user's attention to the important elements of the map) can be enhanced by the use of SCALE-BASED VISIBILITY and SCALE-BASED SYMBOLOGY. This is the use of 'scale ranges' for different data layers so that certain features are only shown at certain map scales (typically showing more features and more annotation as the user zooms in). Likewise Scale can be used to change the symbology of features (again, typically showing more detail as the user zooms in). The use of Scale-Based Visibility and Symbology will be expected on all online maps for ENVS.
11. PURPOSE / Audience
All maps have a purpose which should influence every element of the map and the page layout. A cartographer should be able to clearly articulate the purpose of their map and should keep the audience (who the map is going to be used by) and the client (who the maps is being produced for) in mind. Knowing the purpose and audience of a map drives many of the decisions regarding symbology, map tools to include (or not), Pop-Ups, etc.
Any, or all, of the above 'rules' can be (and frequently have been) violated at the discretion of the cartographer. This is fine IF doing so produces a better map (better serving its purpose and audience). For the purposes of ENVS-418 (Cartography) each of these items will be required on all Interactive maps unless otherwise specified. If you opt not to include any of these elements, be sure to make note of this so we don't think you just forgot something...