We presented this Technical Workshop as part of the 2014 User Conference with the following goal: How to maximize the quality of your web map or app beginning with the selection of the best basemap. There are a number of Esri basemaps available for use at ArcGIS Online. Deciding which basemap to use requires asking a few questions to understand what you are mapping and narrow the options. Our two-page PDF provides the highlights of our workshop.
The matrix categorizes nine ArcGIS.com basemaps based on the level of content and saturation of the maps. Compare those categories against the type of data you are mapping—points, lines, and/or polygons. Answer the series of questions regarding your subject, type of data, geographic area, scale, and purpose of the map.
The two types of data detailed in the matrix are qualitative features, meaning different kinds or types of things being mapped, and quantitative, meaning a range of value or intensity of the data mapped. An example of qualitative data is power plants, symbolized by uniquely colored points for each kind. An example of quantitative data is the amount of CO2 emissions by country, symbolized with a range or scale of color indicating value groups.
Two items to keep in mind:
- The display of quantitative polygons can be impacted by the colors on the basemap, particularly if using transparency.
- The basemaps are in Web Mercator projection. Be aware of distortion when comparing quantitative data, particularly between areas at different latitudes.
You can search for and add basemaps from the ArcGIS Online Gallery, the map viewer basemap gallery, the Living Atlas of the World, or you can add your own custom basemap. Remember, not all basemaps have the same scale range across the globe. Some basemaps are better suited for small-scale, global mapping, while others are intended for detailed, large-scale mapping. Review the online map item pages (for example, Topographic) for a description of each basemap that includes map content and coverage area as well a note when the map was last updated.
Following this step-by-step approach of the matrix and list of questions will allow you to select the best basemap for your map or app.