US Topo - 17 of 29

US Topo FAQs - 29 Found

How can I find the source and vintage of each data layer?

The credit legend, in the lower left-hand corner of the map face, provides a short summary of sources and data currency. 
 
More detailed source information is in an XML metadata file attached to each GeoPDF file. This file contains series-level, quad-level, and layer-level metadata. It does not contain feature-level metadata. For example, the edit dates for individual hydrography features are not preserved in US Topo metadata.
 
The metadata file can be opened by clicking on the paper clip icon in the upper left corner of the table of contents (in Acrobat Reader version XI; behavior in other PDF readers may be different). This opens a folder containing a metadata file, and in maps produced later than mid-2013, a second file with the US Topo symbol key. Both files can be either saved to local disk, or opened from within Reader.
 
XML is plain text and can be read in a browser or editor, but it is intended primarily for automated parsing, not human readability. The second line of the metadata file is a reference to an XSL style sheet that will format the file to make it easily readable: 
<!--<?xml-stylesheet type="text/xsl" href="http://webhosts.cr.usgs.gov/mod/FGDC_Plus.xsl"?>-->
 
This line is commented out because a reference to an online style sheet is a security vulnerability, and some applications do not allow such files to be opened. With genuine USGS files there is no actual security problem, but a counterfeit file could exploit this vulnerability. A style sheet reference to a URL not in theusgs.gov domain would be a warning flag. We know of no actual instances of such counterfeit files.
 
To use the style sheet, save the metadata file to local storage, and edit it with a text editor (e.g., Notepad) to remove the comment characters (<!-- and -->) from the second line. Then open the edited file in Internet Explorer or other appropriate application. As noted above, some applications will not allow the style sheet to be used. IE will allow it, but will display warnings about security and blocked content. Accept these warnings and allow all content to be displayed.
 
Another solution is to copy the .xsl file to the same local storage location as the metadata file, then edit the href parameter in the metadata file to point to the local .xsl file. More applications (including Firefox) will accept this solution.

Tags: Maps, Topographic, Recreation, Quadrangle, GeoPDF, Scale