A Digital Orthophoto Quadrangle (DOQ) is a digital, uniform-scale image
created from aerial photos. It is a photographic map where ground features
are displayed in their true ground position, because relief displacements
caused by the camera and the terrain have been removed. It combines the
image characteristics of a photograph with the geometric qualities of
a map, thus it is possible to get direct measurements of distances, areas,
angles, and positions from a DOQ.
A DOQ may be used as a source or background layer in a geographic information
system (GIS) to collect, review, and revise other digital data. A DOQ
can be combined with a DEM and a DRG to produce an image with additional
visual information for the extraction and revision of base cartographic
To learn more about DOQs, check out the
at the Crater Lake Data Clearinghouse Web site.
The San Francisquito Creek project covers six USGS 7.5-minute quadrangles.
These six quads have been mosaicked together for your convenience of viewing
and analyzing the information throughout the area. Data are reprojected
to one standard projection (UTM NAD27 zone 10 meters). Click on
the following link to download the data:
(181 MB uncompressed) -- DOQ with world file in TIFF format.
(37 MB uncompressed) -- DOQ with world file in Mr. SID format
doq_1948.zip (102 MB
uncompressed) -- Historical DOQ with
world file in Mr. SID format.
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