ESRI ArcGIS Online Free Services
According to Environmental Systems Research Institute, or ESRI:
"... ArcGIS Online Services offers a collection of 2D map services and 3D globe services, as well as task-based functional services, which you can use to support your GIS work... ArcGIS Online Services include a number of online map layers that you can use within your own map documents and applications. These layers include multi-resolution imagery, street maps, topographic maps, shaded relief imagery, and more... ArcGIS Online Services are always available on the Web so users with Internet access can use these services at any time."
See the list of free available services on ESRI's Resource Center website. Additional "Premium" serices are available for a charge, but access to these premium services are not available through the Libraries.
ArcWeb vector and image datasets have been cataloged into GIS Lookup, and are listed below:
- "ArcGIS Online Services" is one of many sources for online streaming data. See the OGC WMS page for additional streaming data sources.
- As with all geospatial web services, only an image of the data is being sent to your desktop client. You are not able to query, edit, export, or otherwise use the data as you would if it were in a file-based vector format stored on your own computer. However, there aren't as noticeable limitations when using raster-based service content (maps and imagery).
- The advantages of geospatial web services are that they allow you to quickly access and view basemap data that are stored and maintained (kept up to date) elsewhere, which saves a lot of work. You can then overlay other existing GIS data stored locally with the basemap data from web services.