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About GeoPDF Maps
USGS Cartographic Data
US Geological Survey manages and distributes many kinds of cartographic data, including GeoPDF data and the new “DigitalMaps – Beta.” Information for most USGS cartographic data is available at http://ask.usgs.gov/1product.html.
About GeoPDF data files
PDF (Portable Document Format) digital files are now available for US Geological Survey topographic quadrangle maps. Each file is essentially a scan of a topographic map with the added feature of being georegistered. The files can be used as a PDF file, enabling users to view topo maps onscreen.
The GeoPDF format is an extension to Adobe's PDF 1.3 and higher versions enabling GIS functionality within standard PDF files. This format is designed for the efficient distribution and communication of rich spatial data to anyone who needs to view, review, verify, update, or print it. Because GeoPDF files are highly compressed and encapsulated, they are smaller, faster, and easier to transmit than GIS data sets, without the overhead associated with typical GIS spatial data sets (or the management of database tables, external links, and dependencies). Using the GeoPDF format, publishers of spatial data can select the specific spatial data they want recipients to see and can publish GIS source files into a single GeoPDF file.
GeoPDF files are not a replacement for native GIS formats. GIS professionals still need the original files for editing or updating spatial data. GeoPDF files enable non-GIS professionals, field technicians, business executives, and their colleagues to utilize rich spatial information. Users can view and print GeoPDF files with the free and ubiquitous Adobe Reader ,and they can do more with the data using a free plug-in called TerraGo Toolbar. Users do not have to install this plug-in to view GeoPDF files.
About the data available in GeoPDF format
The initial set of GeoPDFs was produced by the US Army Corp of Engineers Topographic Engineering Center using existing USGS Digital Raster Graphics (DRGs) (scanned at 250 pixels per inch (ppi)) as the source. The file names reflect the DRG from which they were derived. A USGS project is underway to upgrade all 250 ppi DRGs with higher resolution (400 ppi to 508 ppi) files, which can produce high quality print-on-demand products. Depending on the detail and complexity of the source map, individual GeoPDF file sizes vary from 3 to 30 megabytes, with the majority being in 10-17 megabyte range. In most cases the GeoPDFs reflect the latest version of the published map; those that don't are continually being replaced with higher resolution files created from 508 ppi scans of the paper map.
Comparison of GeoPDF data files