USGS 1 Meter Aerial Photographs (DOQ)
USGS Digital Orthophoto Quadrangles (DOQ) are precision 1 meter per pixel black
and white aerial photographs that have been ortho-rectified to fit the earth's surface
exactly. DOQs are produced by the USGS in UTM coordinates, NAD83. To change to other
coordinates/datums, for example State Plane NAD27, TopoDepot uses a precise method
of raster coordinate projection.
The resulting images are compressed into JPEG files. The size of a single quad DOQ
is about 20MB. A JPEG World file is also produced for use in most CAD and GIS software.
We use JPEG since it is compatible with most software, including all versions of
AutoCAD (V14 and up), and offers reasonable compression for photographs like these.
(You can also view it in any web browser.)
Additionally, if you choose DWG files, the image is combined into the DWG file at
the correct location and scale. Any version of AutoCAD (V14 or greater) can be used
to view these images. AutoCAD Map is not required. If you order multiple quadrangles,
a JPEG file is created for each quad. Adjacent quads will overlap slightly to give
a seamless effect. Multiple quads are handled correctly in AutoCAD.
We have found that the DOQ data is very precise, and lines up very well with the
TopoDepot vector layers. The DOQ layer provides an excellent sense of "ground truth"
when viewing contours, roads, fence lines, rivers, and section lines.
The dates for the USGS DOQ data range from around 1996 to the present.
Data Source: USGS-Microsoft Terraserver project. http://www.terraservice.net
More information:
http://rockyweb.cr.usgs.gov/nmpstds/doqstds.html
