US Geological Survey Imagery Topo Base Map Service from The National Map - This cached tiled topographic base map, with orthoimagery as a backdrop, combines the most current data services (Boundaries, Names, Transportation, Elevation, Hydrography, Land Cover and others) that make up The National Map. New contours generated from the National Map US Topo product are included and are visible along with other data down to the 1:18,000 zoom scale. This his product is designed to provide a seamless view of the data, closely resembling the National Map's US Topo (geopdf) product, in a GIS indigestible format. The Orthoimagery data are typically high resolution aerial images that combine the visual attributes of an aerial photograph with the spatial accuracy and reliability of a map. Digital orthoimage resolution may vary from 6 inches to 1 meter. In the former resolution, every pixel in an orthoimage covers a six inch square of the earth’s surface, while in the latter resolution, one meter square is represented by each pixel. The majority of the imagery service source is from the National Agriculture Imagery Program (NAIP) for the conterminous United States (CONUS). The data is 1-meter pixel resolution with leaf-on. Collection of NAIP imagery is administered by the U.S. Department of Agriculture's Farm Service Agency. In areas where NAIP data is not available other imagery acquired through partnerships by the USGS is used. The National Map program is working on acquisition of large scale imagery for the nonconterminous States of Alaska and Hawaii. For the most part at this time any new Alaska orthoimagery data is not available to be used in this service due to license restrictions. This cached tiled base map also provides a visualization of the free orthoimagery data that is available for download from The National Map at viewer.nationalmap.gov/viewer. WMS Link: http://basemap.nationalmap.gov/arcgis/services/USGSImageryTopo/MapServer/WMSServer?request=GetCapabilitiesservice=WMS Note: The following USGS dynamic topographic imagery service can be used in conjunction with this described tile cache service to provide visualization below 18K: http://services.nationalmap.gov/ArcGIS/rest/services/USGSImageryTopoLarge/MapServer