The U.S. Geological Survey's Larry Moore provides an update on the US Topo effort, the Survey’s general purpose, digital, quadrangle map series. He outlines the successes thus far and the obstacles still ahead in 2013.
In the second half of the 20th century, the foundation of the U.S. Geological Survey’s (USGS) national map series was 7.5-minute topographic maps. This map series was declared complete in 1992. In the 1990s and early 2000s, the USGS mapping program focused its attention on digital data for GIS. In November, 2008, the USGS began defining a new general purpose, digital, quadrangle map series. In 2009, this new series was named “US Topo.” While the older maps were handcrafted products created from primary data sources, US Topo maps are mass-produced from secondary data sources, mostly the GIS databases of The National Map. Because of this difference, the new maps have lower unit cost, better map currency, and better overall coverage, but have less content and do not completely replicate the visual appearance of a hand-drawn map.
The early phases of the US Topo program are discussed in a May, 2011 paper [http://www.directionsmag.com/articles/us-topo-a-new-national-map-series/178707]. In September, 2012, the first three-year production cycle was completed and nearly full coverage of the conterminous United States with a new national map series was achieved.
Mass Production of Contour Maps
The primary strategic goal of the US Topo program is to refresh the national map series for all U.S. states and territories on a regular three-year cycle. For the conterminous 48 states alone, this requires publishing 18,000 maps per year or 72 maps every work day. This production goal has been met for three consecutive years, and between late 2009 and late 2012, the conterminous 48 states were completely covered with new topographic maps.
Maps created in early 2009 were simple image maps without contours or hydrography. These were named “Digital Map – Beta” and are now regarded as experimental and temporary. These maps were removed from public view as they were replaced with contour maps in 2012. In future three year cycles, the older maps will be retained as historical data and will continue to be available for download. The second three year cycle of US Topo production began in October, 2012.
Figure 1 shows map production rates and illustrates the progress on the basic problem of mass production. Each year the production system has become more stable, and in 2012, a steady state was reached with production almost exactly matching targets.
Figure 1. US Topo map production, June, 2009–September, 2012. The primary strategic goal of the program is to refresh the national map series for the United States on a regular three-year cycle. This pace of map production was achieved for the first three-year cycle, 2010–2012.
The second strategic goal of the program is continuous product improvement, which can be divided into two broad categories.
Additional Data Content
The old topographic maps were created from primary sources, including extensive field observation. It is currently not possible to duplicate the content of those maps from The National Map databases, but a goal of US Topo is to add more data layers each year as data are obtained from authoritative sources and integrated into The National Map. The major improvements and content milestones to date are:
- June, 2009 – Production of basic image maps started.
- October, 2009 – Contour and hydrography layers added.
- May, 2010 – Road data source changed from Census Bureau to commercially licensed data from TeleAtlas/TomTom.
- October, 2010 – Production of maps over National Forests started, with National Forest boundaries and roads provided by the U.S. Forest Service.
- April, 2011 – State and county boundaries added.
- October, 2011 – Timber coverage layer added.
- May, 2012 – Railroads added for selected track provided by the Federal Railroad Administration.
- May, 2012 – Public Land Survey System data added for selected western states; data provided by the Bureau of Land Management.
Additional content planned for 2013 includes a shaded relief layer, National Parks and other selected federal land boundaries, and recreational trails in National Forests. In all cases, new content depends on receiving data from authoritative sources. For non-natural map features, the USGS no longer gathers data by direct field observation or from primary sources.
Continuous content improvement does have some minor drawbacks for map users. Adding a new feature class improves the quality of maps containing that feature, but temporarily reduces the consistency of the series as a whole. To minimize this problem, the USGS typically adds new content for an entire state at one time. To further help with symbol clarity, an attachment containing cartographic symbols used on US Topo maps will be included in the US Topo GeoPDF starting in the spring of 2013. The three to five year goal is to have a legend on each US Topo showing the feature set at the time the map was made.
Improved Cartographic Presentation
Traditional maps are part scientific documents and part works of art, and computers cannot yet create the graceful appearance of a traditional hand-drawn map from normal GIS data. Challenges include text placement, integration of different feature classes, and positioning crowded features while maintaining clarity. US Topo maps’ visual appearance is superior to a typical GIS display, but still falls short of traditional USGS topographic map presentation standards.
Nevertheless, the first US Topo production cycle included many improvements to automated map layout. The production software can now automatically avoid most overprints of both text and features. Label density, especially for road and street names, has steadily improved. Contours and water bodies are more tightly integrated than in 2010. The overall appearance and readability of the maps has improved even as more content has been added and unit production cost has decreased.
Figure 2. The images compare the linework content of a 2009 “Digital Map – Beta” (left) with the 2012 US Topo of the same area (right). The orthophoto layer is turned off in both images. Although US Topo still does not have all the feature classes of traditional USGS topographic maps, much progress has been made since the program started. More feature classes will be added in 2013. US Topo maps also have content the old topographic maps did not, such as the orthoimage layer.
Placement of name labels for physiographic features is still a significant issue. This is not primarily a software problem, but a more basic data problem. Most GIS data consists of spatial objects (points, lines, and polygons). Proper names are attached to these objects as attributes, and software can use the geometry of the spatial object to infer how text labels should be placed. However, for almost all nonwater natural features in the United States (such as canyons, mountains, plateaus, and mesas), no spatial database has ever been constructed. The official database of natural feature names, the Geographic Names Information System (GNIS), began in the 1970s as a digital repository for the records of the Board on Geographic Names (BGN). Defining boundaries for canyons and mountains was problematic, and at the time was of questionable value, and was therefore not attempted. The USGS has begun work on a national database of spatial objects for natural features, but this is an expensive, multi-year effort. The current lack of such a database is one obstacle to increasing the visual quality of mass-produced maps in a national map series.
Figure 3. Text placement for some natural features is still a problem. Water feature names are associated with GIS geometry in the National Hydrography Dataset, so the label “Trout Cr” follows the stream as on a traditional map. Because “Sulphur Mountain” is a small feature, the name is associated with a single point (the hill summit), so this label is also placed correctly. However, “Hayden Valley” and “Crater Hills” are large areal features, and their labels cannot be placed properly by software because the names are associated with single points, not areas, in the Geographic Names Information System.
US Topo and Geographic Information Systems
US Topo was designed for map users who are not GIS specialists. The product’s primary purpose is to present GIS data as traditional maps that can be used on normal office computers without specialized software or expertise. The program creates no new data, but only repackages existing data. Almost all the data that goes into a US Topo are available in GIS formats free of charge from The National Map databases (roads, which are commercially licensed data, are the major exception).
Nevertheless, traditional symbolized and annotated maps have value even for advanced GIS users, and there is demand to have a GIS-loadable version of US Topo maps. This was not anticipated when the product was designed, and it is not a simple problem. One solution would be for GIS vendors to implement geospatial PDF import; this is technically difficult, and at this writing very little software of this kind is available. Another solution would be for the USGS to create companion products that mirror US Topo content and presentation, but are in GIS-friendly formats. The USGS is working on such products, and will probably begin serving some layers in 2014. These products will be in Esri geodatabase format with an associated template to define symbolization.
These new products may also provide better support for mobile applications.
US Topo Demand and Product Distribution
US Topo maps are distributed through an http download service. The USGS maintains two interfaces to this service, the “Map Locator and Downloader” application at http://store.usgs.gov, and The National Map Viewer at http://viewer.nationalmap.gov/viewer/.
Demand for US Topo maps has increased with supply, and in 2012, demand increased sharply as full coverage of the 48 states was approached.
Figure 4. The rate of map download has increased rapidly as coverage has improved, and in mid-2012 was near 4,000 maps per day, a large number for a USGS data product. A total of about 1.8 million maps were downloaded from USGS web sites between July, 2009 and October, 2012.
Demand for bulk distribution (deliveries of thousands of products at one time) has also grown. An efficient and standard mechanism for bulk distribution remains to be developed, though the USGS recognizes the need and is considering several possibilities. For now, bulk deliveries are accomplished by either loading files on customer-provided portable hard drives, or by sending customers a customized batch file that automates multiple downloads. The USGS is also hopeful that private companies will rehost US Topo maps and provide a wider range of delivery options.
For some applications—including outdoor recreation, wildfire management and suppression, and some kinds of emergency response—paper maps are still important. The US Topo maps present new challenges for creating and distributing paper maps.
The layered PDF format makes it easy to print the maps to scale, and to print any desired combination of layers. However, printing a full map sheet requires a large-format plotter, equipment not normally owned by individuals or small offices. High-quality or weather-resistant plots require more specialized and expensive equipment. The USGS is pursuing a printing contract that will allow the USGS to continue to sell paper maps. In the long run we are hopeful that printing can be partially or completely privatized.
Another aspect of the printing problem is that US Topo maps contain too many data layers to print together. Printing the contours over the orthoimage, for example, often makes both layers almost unreadable. This problem will get worse as more data layers are added. This may mean that the standard paper topographic map is truly a thing of the past, and the future belongs to customized, print-on-demand products.
US Topo in Alaska, Hawaii and U.S. Territories
The first years of the US Topo program concentrated on covering the conterminous 48 states, but in the next few years the program will address other areas:
- Hawaii is scheduled for production in early 2013.
- Planning for Alaska began in 2012 with inter-agency discussions and creation of a few prototype maps. Production of US Topo maps at 1:25,000 scale will start in 2013. The production schedule will be driven by the availability of new elevation and image data being collected by the Alaska Statewide Digital Mapping Initiative. About 12,000 maps are needed to cover Alaska. Full state coverage is expected by about 2017.
- New elevation and image data over Puerto Rico and the Virgin Islands are being collected by the Army Corps of Engineers. When these new datasets are available, hopefully in 2013, US Topo maps at 1:20,000 scale will be created for these areas.
- The Pacific Territories are also traditionally within the USGS mapping domain. The US Topo program intends to produce maps over these areas, but no schedules have yet been set.
The Historical Topographic Map Collection
A separate USGS project, the Historical Topographic Map Collection (HTMC), is scanning the entire USGS topographic map library. This collection consists of about 200,000 map sheets dating back to 1884. The initial production phase of this project is nearly complete, and high-resolution scans in GeoPDF format have been published and are available to the public for free download.
As the second threeyear production cycle for US Topo begins in late 2012, earlier US Topo maps will remain available and will become part of the historic collection, creating a single, freely available library of USGS topographic maps covering more than 130 past years and extending into the future.
The primary goal of the US Topo program, defined in November, 2008, is to refresh the topographic map series for the entire country on a three-year cycle. In the first cycle (2010–2012), the necessary production pace was achieved and sustained for the conterminous 48 states. This accomplishment lays the foundation for improving the product and expanding the program in the years ahead.
The emphasis on a rapid map-production cycle is unprecedented in USGS mapping programs, and perhaps in any national mapping program. In all older USGS topographic programs, a primary goal was to make every map error-free. This goal, plus the fact that traditional maps were compiled and finished by hand, necessarily meant that any particular area would be mapped infrequently. The US Topo program changes this traditional philosophy, and asserts that the map series as a whole is better served by automated production, on a short refresh cycle, using the best available authoritative data sources.
The program achieved its goals for the first production cycle, and is now expanding in several directions, including adding more content and improving the readability of the base product, defining hardcopy products, defining and producing GIS-friendly products, and covering U.S. areas of interest outside the conterminous 48 states.
For More Information
- The National Map home page has more information.
- US Topo maps are derived from The National Map GIS data. These source data can be downloaded through several different interfaces, including The National Map viewer.
- See also the US Topo home page or the Historical Topographic Map Collection (HTMC).
- US Topo and HTMC maps are published in PDF format, and can be downloaded free of charge through either The National Map viewer, or the “Map Locator and Downloader” application at the USGS Map Store.
- The National Hydrography Dataset
- The Geographic Names Information System.
- Contours on US Topo maps are derived from the National Elevation Dataset
- The Alaska Statewide Digital Mapping Initiative
- “Pacific Territories” refers to Pacific lands within the scope of the Department of Interior Office of Insular Affairs