What is a digital orthophoto quadrangle (DOQ) or orthoimage?

A digital orthophoto quadrangle (DOQ)--or any orthoimage--is a computer-generated image of an aerial photograph in which displacements (distortions) caused by terrain relief and camera tilts have been removed. It combines the image characteristics of a photograph with the geometric qualities of a map.

Unlike an aerial photograph, an orthoimage has a uniform scale, so it can be used as a base map onto which other map information is overlaid. It is possible to measure directly on an orthoimage, just like other maps.

Air photo showing distorted path of pipeline as it crosses hills and valley, and orthophoto showing the true, straight path

Comparison of an aerial photograph and an orthophoto (orthoimage) from the Tenth Legion quadrangle in Virginia near the town of Arkton. The aerial photo shows a straight pipeline that is distorted by displacements caused by camera tilting and terrain relief (topography). The orthophoto removes the effects of tilt and relief and shows the true, straight path of the pipeline. Unlike the aerial photo, the orthoimage is a photographic map with a uniform scale. The orthoimage can be directly laid over other maps (and vice versa).

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Will I be able to see my house in an aerial photograph? Will enlarging the image let me see more detail?

The ability to see specific items in an aerial image is mostly a function of scale and resolution. The following aerial photography products all have a resolution of 1 meter or better, so you should be able to see an object the size of a house: High Resolution Orthoimagery (HRO) National Agriculture Imagery Program (NAIP) imagery Digital...

Are the scanned aerial photographic images georectified?

Scans of traditional aerial photography film products (air photos) are not georectified . The USGS does, however, offer several orthoimagery (georectified aerial photograph) products: Digital Orthophoto Quadrangle (DOQ) High Resolution Orthoimagery (HRO) National Agriculture Imagery Program (NAIP, NAIP Plus) NAIP orthoimagery has been collected...

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There are several imagery services for The National Map. A complete list of service URLs is at The National Map-Service Endpoints . Go to imagery service URLs to view service parameters, formats, and contact information. Some imagery services are cached and some are dynamic: USGSImageryOnly (under Base Maps), for example, is a tile cache base map...

How can I download orthoimagery in bulk?

Orthoimagery is offered through a bulk data application in EarthExplorer . Go to the EarthExplorer Help page and select "Bulk Download Tutorial". To receive bulk data via external hard drive, you must supply the hard drive(s) within our specifications, pay for shipping the drive(s), and provide a paid return label or a carrier account number. Send...

Why does my orthoimagery search on The National Map return multiple tiles for downloading?

Orthoimagery is usually very large in file size, so we stage the data in "tiles" that can be reasonably transported over the Internet. Orthoimagery from the National Agriculture Imagery Program (NAIP) that is distributed via The National Map Data Download is in compressed 10:1, JPEG2000 format in 3.75 minute x 3.75 minute tile extents. A larger...

How do I download orthoimagery products and what are the available formats?

Download orthoimagery (georectified aerial photographs) using EarthExplorer , which has the full catalog of USGS orthoimagery and aerial photography, or The National Map download client , which has NAIP orthoimagery only. EarthExplorer : Products Overview Format varies by type of orthoimagery: Native format, Georeferenced Tagged Image File Format...
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Air photo showing distorted path of pipeline as it crosses hills and valley, and orthophoto showing the true, straight path

Aerial Photograph vs. Orthoimage

Comparison of an aerial photograph and an orthophoto (orthoimage) from the Tenth Legion quadrangle in Virginia near the town of Arkton. The aerial photo shows a straight pipeline that is distorted by displacements caused by camera tilting and terrain relief (topography). The orthophoto removes the effects of tilt and relief and shows the true, straight path of the pipeline

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