ArcGIS Online keeps growing in popularity, with more and more users contributing their content to share with others. The volume of publicly shared items, as well as items shared through groups, has grown significantly in the last six months. In addition, Esri also continues to publish its own content derived from commercial and other data sources. Users can freely access all this content, including web maps, map services, and layer/map packages, through ArcGIS or a browser.
Users looking for imagery services will be interested in the new NaturalVue imagery, created by MDA Information Systems, Inc., that has been published as a web map and as an ArcGIS Server image service. This provides a nice example of how imagery can be published dynamically for use as an attractive basemap in GIS and web applications or as the source for applications of approximate georeferencing and color correction of smaller-scale imagery. The NaturalVue 15-meter satellite imagery of the world is a natural-color seamless mosaic compiled from more than 8,600 Landsat-7 multispectral images. It's a single, consistent global dataset with a spatial resolution of 0.5 arc seconds and a positional accuracy of better than 50 meters RMSE.
United Nations Second Administrative Level Boundaries (UN SALB) are authoritative datasets published by the UN Geographic Information Working Group. The goal of the working group is to provide the international community with global, seamless, and standardized datasets, country by country, that support comparative analyses for such issues as mapping of the AIDS crisis and development in a particular region or the movement of displaced populations in conflict zones. Changes to borders and internal boundaries are updated frequently by respective national mapping agencies, making this data essential for accurate analyses by international aid agencies around the globe. These datasets have been published under the UN SALB group in ArcGIS Online and are publicly available for download as individual layer packages by country for use in ArcGIS Desktop.
The National Maps for USA group in ArcGIS Online has been created with the federal user community in mind. This group features web maps, map services, and layer packages from several leading government and commercial providers, including i-cubed, National Geographic Society, National Oceanic and Atmospheric Administration (NOAA), Tele Atlas, US Department of Agriculture Farm Services Agency, US Environmental Protection Agency, the US Geological Survey, and more.
The purpose of this group is to provide basemaps or operational layers for use in web mapping applications or to create simple mashups together with other map layers. Some examples include the US Land Cover Map, a web map that presents levels of land-cover classification for the continental United States based on Landsat 2001 imagery; Soil Survey Map of USA, a web map that features the Soil Survey Geographic database by the US Department of Agriculture's Natural Resources Conservation Service; USA National Wetlands Inventory, a web map that presents wetlands and deepwater habitats of the United States and its trust territories based on the National Wetlands Inventory published by the US Fish and Wildlife Service; and USA Thunderstorm Probability Forecasts, a web map that references a thunderstorm probability forecast map service that is updated hourly and published by the National Weather Service.
To find this content, visit ArcGIS.com and select Search for Groups or Search for Maps, then enter the group name or keyword, for example, NaturalVue.
As of the end of January 2011, ArcGIS Online basemaps published and hosted by Esri have been freely available to all users for internal or external use. This means that users have free access to ArcGIS Online basemaps including World Imagery, World Street Map, World Topographic Map, USA Topographic Maps, and DeLorme World Basemap, as well as demographic, reference, and other specialty maps.
For some time, local, state, and federal government agencies have already been able to use ArcGIS Online basemaps at no cost for internal and external use. With this new policy, Esri is giving all users the opportunity to leverage these high-quality maps for their applications. Developers also have unlimited access to ArcGIS Online basemaps for development and testing purposes via the ArcGIS Web Mapping APIs, ArcGIS Mobile SDKs, and ArcGIS Engine.
The only restriction that applies to private-sector users is a high-volume limit of 50 million transactions in a 12-month period—a volume that very few users will likely reach. Users from the private sector who believe that their application may generate more than 50 million map transactions within that period should contact the Esri regional office in their area to discuss alternatives.
ArcGIS Online basemaps are a built-in feature of ArcGIS Desktop and ArcGIS Server, among other ArcGIS products. Users who do not have these products can still access ArcGIS Online basemaps through other clients and applications, including ArcGIS Mobile SDKs and ArcGIS Web APIs. Some ArcGIS clients are free, for example, ArcGIS Explorer (online and desktop) or the ArcGIS Online web portal (arcgis.com).
Look for this column in future issues to get regular updates on new content in ArcGIS Online. To start using maps, apps, and other resources, visit ArcGIS.com, the web portal for all ArcGIS Online content. To learn more about ArcGIS Online basemaps, visit esri.com/mapservices.