Duck Keys in the Florida Keys along Overseas Highway. Source imagery is Monroe County, 

Florida, March 2006.

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2009–3055

Reprinted April 2010

The National Map—Orthoimagery

Printed on recycled paper

Orthoimagery

Orthorectified digital aerial photographs and satellite 

images of 1-meter (m) pixel resolution or finer make up the 

orthoimagery component of The National Map. The process 

of orthorectification removes feature displacements and scale 

variations caused by terrain relief and sensor geometry. The 

result is a combination of the image characteristics of an aerial 

photograph or satellite image and the geometric qualities of a 

map. These attributes allow users to:

• Measure distance

• Calculate areas

• Determine shapes of features

• Calculate directions

• Determine accurate coordinates

• Determine land cover and use

• Perform change detection

• Update maps

The standard digital orthoimage is 

a 1-m or finer resolution, natural color 

or color infra-red product. Most are now 

produced as GeoTIFFs and accompanied 

by a Federal Geographic Data Committee (FGDC)-compliant metadata file. 

The primary source for 1-m data is the 

National Agriculture Imagery Program 

(NAIP) leaf-on imagery. The U.S. Geological Survey (USGS) utilizes NAIP 

imagery as the image layer on its “Digital-Map”—a new generation of USGS 

topographic maps (http://nationalmap.

gov/digital_map/). However, many Federal, State, and local governments and 

organizations require finer resolutions to 

meet a myriad of needs. Most of these 

images are leaf-off, natural-color products at resolutions of 1-foot (ft) or finer.

Applications of Orthoimagery

Digital orthoimagery is one of the 

base layers for most public and private 

Geographic Information Systems (GIS) 

and supports various geographic information analysis and mapping applications. 

These data are used to develop and revise vector files of 

transportation, cadastral, and land-use/land-cover information. 

Federal, State, and local agencies use orthoimagery for base 

maps for wetlands, soil, land parcel, farm-field boundary, forest 

inventory, and other natural-resource mapping, analysis, and 

planning applications. Local governments rely on orthoimagery 

to map land-property boundaries and to manage their streets and 

other infrastructure assets. Orthoimagery serves as a seamless 

base map layer to which many other layers are registered, can 

be combined with digital elevation data for 3-D modeling and 

slope and terrain analyses, and is easily mosaicked to create 

seamless images of larger areas. Digital orthoimagery provides 

visual information for the following partial list of applications.

• Image layer for topographic maps

• Homeland Security

• Homeland Defense and Emergency Management

• Public Safety Planning, Response, and Mitigation
Niagara Falls, along the border of New York and Ontario, 

Canada. Source imagery is New York State, April 2005.

Hoover Dam in the Black Canyon on the Colorado River, 

September 2006.

• Tax Parcel Mapping

• Transportation Management

• Operations and Planning

• Economic Development

• Utilities Management, Operations, and Planning

• Land Planning and Zoning

• Drainage Planning and Management

• Code and Permit Enforcement

• Agriculture

• Insurance

• Surveying and Mapping

• Environmental Management

• Planning and Regulation

• Education

• Natural Resource Inventories and Assessments

Orthoimagery Plans and Data Availability

The orthoimagery maintenance plan consists of two 

parts: 1) 1-m resolution, leaf-on, NAIP digital orthoimagery 

are acquired through the Farm Service Agency (FSA) (http://

www.fsa.usda.gov/FSA/apfoapp?area=home&subject=maps&

topic=landing). Files of 1-m NAIP imagery will be collected 

on a 3-year cycle beginning in 2009, whereas files of leafoff imagery are acquired as partnership requirements dictate. 

The USGS will partner with FSA for NAIP imagery for the 

2009–2011 cycle. 2) 1-ft leaf-off orthoimagery over 133 urban 

areas are acquired by the USGS in partnership with the National 

Geospatial-Intelligence Agency (NGA) and State and local 

governments under the Homeland Security Infrastructure 

Program (HSIP). This program initially was created to collect 

imagery and other geospatial data layers over densely populated 

urban areas for homeland security and emergency operation 

purposes, but has expanded beyond its Federal scope to become 

one of the primary mechanisms available to Federal, State, and 

local governments and organizations for partnering to collect 

high-resolution imagery. This effort leverages the resources of 

multiple partners to achieve significant cost savings through 

economies of scale while meeting imagery requirements beyond 

the basic needs of the Federal government—larger collection 

areas, finer resolutions, and 4-band imagery are common “buyups” to the standard urban area product. The standard images 

are 1-ft, leaf-off orthoimages that cover a 1,500-m x 1,500-m 

footprint, georeferenced to the North American Datum of 1983 

(NAD 83) datum and the Universal Transverse Mercator (UTM) 

coordinate system, and are true-RGB, GeoTIFF images with 

FGDC-compliant metadata. The largest 50 cities are acquired on 

a 2-year cycle with the remaining cities on a 3- to 4-year acquisition cycle. Both maintenance programs focus on partnerships 

with Federal, State, and local agencies to leverage resources and 

expand collection coverage.

Dissemination of 1-m or finer resolution digital orthoimagery acquired by USGS through contracts, agreements with 

other Federal, State, Tribal, or regional organizations, or direct 

purchases from private industry data vendors, are available 

through The National Map Seamless Data Distribution Service 

(http://seamless.usgs.gov/), a USGS Internet site for viewing 

and downloading no-cost, public-domain data.

Other Federal, State, and local agencies have their own 

programs for disseminating data independent of the USGS. The 

USGS will not duplicate orthoimagery data holdings unless 
Falls Park on the Big Sioux River, Sioux Falls, South Dakota. 

Source imagery is Minnehaha County, South Dakota, April 2008.

archiving or disseminating the data is part of a cooperative 

agreement; rather, the USGS will rely on those agencies to 

make their orthoimagery accessible on a National Spatial Data 

Infrastructure (NSDI) Clearinghouse node in the public domain. 

Whenever possible, USGS will link to other sites and services 

for orthoimagery data. Selected Internet sites to search for 

orthoimagery data distribution and web image services are:

• Geospatial One-Stop (http://gos2.geodata.gov/wps/portal/

gos/) 

• The National Map (http://nationalmap.gov/) 

• The National Digital Orthophoto Program (NDOP) site 

(http://www.ndop.gov/data.html)

National Digital Orthophoto Program (NDOP)

The NDOP leads the effort to complete and maintain 

national orthoimagery coverage with a resolution that is 1-m or 

finer. The NDOP is a consortium of Federal and State agencies, 

principally the USGS, FSA, Natural Resources Conservation 

Service, U.S. Forest Service, Bureau of Land Management, 

Federal Emergency Management Agency, Bureau of the Census, National Oceanic and Atmospheric Administration, and 

National States Geographic Information Council (NSGIC), 

committed to providing national orthoimagery coverage by 

combining funding resources and creating partnerships to 

coordinate requirements and costs with Federal, State, other 

government agencies, and the private sector.

The Nation Needs The National Map

As one of the cornerstones of the U.S. 

Geological Survey’s (USGS) National 

Geospatial Program, The National Map is 

a collaborative effort among the USGS and 

other Federal, State, local, and Tribal partners 

to improve and deliver topographic information for the Nation. The National Map has 

many uses ranging from recreation to scientific 

analysis to emergency response. The National 

Map is easily accessible for display on the 

Web, as products and services, and as downloadable data. The geographic information 

available from The National Map includes 

orthoimagery (aerial photographs), elevation, 

geographic names, hydrography, boundaries, transportation, structures, and land cover. 

Other types of geographic information can be 

added within the viewer or brought in with 

The National Map data into a Geographic 

Information System to create specific types of 

maps or map views. 

The National Map is a significant 

contribution to the National Spatial Data 

Infrastructure (NSDI) and provides high quality, integrated geospatial data and improved 

products and services including new generation digital topographic maps. The National 

Map also is foundational to implementation of 

the Department of the Interior (DOI) Geospatial Modernization Blueprint and meeting the 

DOI mission. The National Map underpins 

the USGS Science Strategy, which is based 

on a systems approach to help address multifaceted issues, provide better understanding of 

earth processes, and evaluate broad causes and 

consequences of the use and management of 

natural resources. The National Map promotes 

interdisciplinary science by providing nationally consistent, trusted geospatial data, and 

establishing a consistent national geographic 

context.
Journey to Atlantis ride, Sea World, San Diego, California, March 2005.

Partnership Opportunities

Organizations interested in partnering with the USGS to develop orthoimagery data for The National Map can contact 

the USGS geospatial liaison in their State. The list of liaisons is available at http://www.usgs.gov/ngpo/ngp_liaisons.html

Further Information

Further information about The National Map and orthoimagery is available from the National Geospatial Program at 

http://www.usgs.gov/ngpo/.

For information on other USGS products and services, call 1-888-ASK-USGS, or visit the USGS Publications Warehouse at http://www.usgs.gov/pubprod/. For additional information, visit the USGS home page at http://www.usgs.gov/.

Publishing support provided by:

Rolla Publishing Service Center