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USGS QUADRANGLES IN GOOGLE EARTH
By Thomas G. Davis1, PhD, PE, PLS and Rollins Turner 2, PhD
INTRODUCTION QUADS (http://www.metzgerwillard.us/quads/) is a web-based service for visualizing USGS quadrangle boundaries in Google Earth that provides an easy-to-use framework for retrieving geospatial PDF topo maps. QUADS also includes USGS overlays for topographic-bathymetric and hydrographic maps. QUADS The principal component of QUADS is a Google Earth network link that plots approximate USGS quadrangle boundaries (Fig. 1) and provides direct access to 127,692 geospatial PDF maps, including scans of the last historical paper map in all available grid sizes. All quadrangle balloons (Fig. 2) contain name, primary state, nominal grid size, scale, imprint year, and file size information with a link to the corresponding PDF map. Use the All maps with this name link to search for older historical maps or newer current maps in the USGS Topographic Map Collection (USGS 2015c). See USGS (1995) for a discussion of various map series and USGS (2005) for a list of topographic map symbols. Quadrangles are categorized by map series (Table 1) and collected in grid-size subfolders. Coverage includes the conterminous United States, Alaska, Hawaii, Puerto Rico, the US Virgin Islands, Guam, American Samoa, Micronesia, Palau, the Northern Mariana Islands, and portions of Canada. The user is prompted to zoom in if there are more than 1000 quadrangles in view. If there are no quadrangles within the viewer bounding box, the Search Results network link will contain an empty folder named OutOfRange. Topographic PDFs were initially produced by the US Army Corps of Engineers Topographic Engineering Center, currently known as the US Army Geospatial Center, using existing digital raster graphics (DRGs). Traditional topographic PDFs produced by the USGS are created from high-resolution scans of paper maps and compose the Historical Topographic Map Collection (HTMC) (USGS 2017a). The current electronic map series, US Topo (USGS 2017e), is created by the USGS National Geospatial Technical Operations Center from The National Map (TNM) data, including color orthoimagery. The QUADS database and this document will be updated periodically to reflect changes in the USGS map offering (USGS 2017d).
1 Metzger + Willard, Inc., 8600 Hidden River Parkway, Suite 550, Tampa, FL 33637.
E-mail: email@example.com 2 Computer Science and Engineering, University of South Florida, Tampa, FL, retired.
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Table 1. Topographic Map Series
Series Source Count
US Topo The National Map 60,515
HTMC Historical Topographic Maps 67,177 Until June 2017, georeferenced PDF maps were created with software from TerraGo Technologies (GeoPDF maps), and geospatial functions were delivered by the TerraGo Toolbar (TerraGo 2017, USGS 2016). US Topo maps created after June 2017 use a different implementation of georeferencing based on Adobe's geospatial extensions to ISO 32000 (USGS 2017f). Both types of maps can be viewed and printed with Adobe Reader or Acrobat, and although the TerraGo Toolbar is not forward compatible with the new maps, the built-in geospatial functions of Adobe Reader and Acrobat are backward compatible with the older GeoPDF maps, including all HTMC maps.
Figure 1. USGS Quadrangles
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Refresh Mode The Refresh Mode network links provide a uniform mechanism to control the Search Results and Overlays network links. When Refresh Mode is Manual, the contents of the network links are effectively frozen, allowing the user to pan and zoom without prompting a network link refresh. This is particularly useful for inspecting overlays or gaining an overview of network link contents. To initiate a network link:
1. Position the area of interest (AOI) in the viewer. 2. Check the Search Results network link (Fig. 1) to display quadrangle placemarks
and boundaries, or check one of the Overlays network links (Figs. 3 and 4) to display USGS ground overlays.
3. On subsequent uses, reposition the AOI and ensure that the network link is checked and selected. When Refresh Mode is Automatic, search results are refreshed two seconds after camera movement stops. When Refresh Mode is Manual, choose Refresh from the Edit menu, or right-click and select Refresh in the context menu.
The Manual and Automatic network links may be used to stop and start refreshes for the Search Results and Overlays network links. The default refresh mode is Automatic. To stop refreshes, check Manual; to restart refreshes, check Automatic. Canceling an edit of network link properties will disable mode selection for that particular network link.
Figure 2. Quadrangle Balloon
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Overlays Overlay layers (Table 2) are implemented as network links that retrieve multiresolution images via a Representational State Transfer (REST) export. All requests are directed first to the QUADS server where bounding box coordinates are conformed to service requirements before being passed to the service provider.
Table 2. Overlay Layers
Layer1 Service2 Extent3
TopoMaps4 REST5 US6
Hydrography7 REST8 CONUS9
1 Overlays network link name 2 Service type 3 Service coverage area 4 USGS topographic-bathymetric digital
raster graphics (Esri 2017) (Fig. 3) 5 USA Topo Maps server (Esri 2014)
6 Conterminous US, Alaska, and Hawaii 7 National Hydrography Dataset (NHD)
(USGS 2017b) (Fig. 4) 8 EPA Office of Water NHDPlus server (EPA
2017) 9 Conterminous US
When the viewer bounding box is outside the coverage area, requests are not forwarded to the service provider, and the associated Overlays network link will contain an empty folder named OutOfRange. See USGS (2017c) for other layers available from the USGS.
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Figure 3. Topographic-Bathymetric Digital Raster Graphics
Figure 4. National Hydrography Dataset
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CONCLUSION QUADS provides user-friendly, graphically oriented access to a wealth of publicly available geospatial information maintained by the USGS. Metzger + Willard, Inc. is pleased to make QUADS freely available to anyone having Google Earth installed on a computer with an Internet connection. ACKNOWLEDGMENTS The authors wish to thank the following individuals for their help in implementing or testing QUADS: Jeff Wendel and Andy Orona, USGS; Scott Brown, PLS, George F. Young, Inc.; and Kemp Morris, PSM, Morris Surveying, Inc. Special thanks are extended to Steve Skelton, USGS. REFERENCES EPA (2017). "WATERS Mapping Services." (https://www.epa.gov/waterdata/waters-
mapping-services) Esri (2017). "USA Topo Maps." (http://goto.arcgisonline.com/maps/USA_Topo_Maps) Esri (2014). "USA Topo Maps (MapServer)."
(http://server.arcgisonline.com/ArcGIS/rest/services/USA_Topo_Maps/MapServer) TerraGo Technologies (2017). "TerraGo Toolbar."
(http://www.terragotech.com/products/terrago-toolbar) United States Geological Survey (2017a). "Historical Topographic Maps."
(https://nationalmap.gov/historical/) United States Geological Survey (2017b). "National Hydrography Dataset."
(https://nhd.usgs.gov/) United States Geological Survey (2017c). "The National Map Small-Scale Web
Services." (https://nationalmap.gov/small_scale/infodocs/webservices.html) United States Geological Survey (2017d). "US Topo and Historical Topographic Map
Collection." (https://geonames.usgs.gov/pls/topomaps/) United States Geological Survey (2017e). "US Topo: Maps for America."
(https://nationalmap.gov/ustopo/) United States Geological Survey (2017f). " US Topo Map Users Guide
(https://nationalmap.gov/ustopo/quickstart.pdf) United States Geological Survey (2016). "US Topo Map and Historical Topographic
Map Users Guide." (https://nationalmap.gov/ustopo/USTopo_HTMC_quickstart.pdf)
United States Geological Survey (2005). "Topographic Map Symbols." (https://pubs.usgs.gov/gip/TopographicMapSymbols/topomapsymbols.pdf)
United States Geological Survey (1995). "USGS Maps Booklet." (https://pubs.usgs.gov/gip/usgsmaps/usgsmaps.html)