DOQQ

Digital Orthophoto Quarter Quads (DOQQ) are aerial photos with geometric map qualities used by the U.S. Geological Survey (USGS). The aerial photos are adjusted to eliminate distortion before the adding of the qualities, this is called orthorectification. The DOQQs are georectified as well.


The map shown is a Digital Orthophoto Quarter Quads (DOQQ) Map of San Francisquito Creek Watershed. This map was created to help determine how to resolve an overflow problem in the area. The shading is to help show specific areas that need attention.


http://geography.wr.usgs.gov/sfcreek/maplayout.html