U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2007-3008

January 2007

The National Map - Orthoimagery Layer

The Nation Needs The National 

Map

Many Federal, State, and local agencies 

use a common set of framework 

geographic information databases as 

a tool for economic and community 

development, land and natural resource 

management, and health and safety 

services. Emergency management and 

homeland security applications rely 

on this information. Private industry, 

nongovernmental organizations, 

and individual citizens use the same 

geographic data. Geographic information 

underpins an increasingly large part of 

the Nation’s economy.

The U.S. Geological Survey (USGS) 

is developing The National Map to be 

a seamless, continually maintained, 

and nationally consistent set of online, 

public domain, framework geographic 

information databases. The National 

Map will serve as a foundation for 

integrating, sharing, and using data 

easily and consistently. The data will be 

the source of revised paper topographic 

maps. The National Map includes 

digital orthorectified imagery; elevation 

data; vector data for hydrography, 

transportation, boundary, and structure 

features; geographic names; and land 

cover information. 

Orthoimagery

Orthorectified digital aerial photographs and satellite images of 1-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 easily:

• Measure distance

• Calculate areas

• Determine shapes of features

• Calculate directions

• Determine accurate coordinates

• Determine land cover & use

• Perform change detection

• Update maps

The traditional digital orthoimage 

is a 1-m resolution, 1:12,000 scale, 

panchromatic, natural color or 

color infra-red, quarter quadrangle 

product. It was initially built to USGS 

specifications, which included an ACSII 

header with descriptive information 

about the data. Many are now produced 

as GeoTIFFs and accompanied by an 

FGDC-compliant metadata file. The 

primary source for 1-m data is the 

National Agriculture Imagery Program 

(NAIP) which is leaf-on imagery. 

However 1-m, leaf-off orthoimagery is 

a common product in the eastern United 

States. 

Applications of Orthoimagery

Orthoimages provide information not easily represented on symbolized 

maps. (Holder, Fla.)

Digital orthoimagery 

is the foundation 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.

• Homeland Security 

• Homeland Defense & Emergency 

Management

• Public Safety Planning, Response, 

& Mitigation

• Tax Parcel Mapping

• Transportation Management

• Operations & Planning

• Economic Development

• Utilities Management, Operations, 

& Planning

• Land Planning and Zoning

• Drainage Planning & Management

• Code & Permit Enforcement

• Agriculture

• Insurance

• Surveying & Mapping
• Environmental Management

• Planning & Regulation

• Education

• Natural Resource Inventories and 

Assessments

Homeland Security Infrastructure 

Program (HSIP)

Many Federal, State, and local agencies 

now require a product with 1-ft or finer 

resolution, especially over densely 

populated urban areas. The USGS, 

National Geospatial Intelligence 

Agency, and Federal Geographic 

Data Committee initiated the HSIP 

which acquires 1-ft resolution digital 

orthoimagery and other data layers for 

selected U.S. cities through contracts and 

partnerships with other organizations. 

Those images cover a 1500m x1500m 

footprint, georeferenced to NAD83 

datum and UTM coordinate system, and 

are true-RGB, GeoTIFF images with 

FGDC-compliant metadata. The HSIP 

has a 2-year acquisition cycle for 50 

selected cities and a 4-year cycle for the 

remaining 83. Security and emergency 

operations over heavily populated urban 

areas provide the context for these 

coverages. 

National Digital Orthophoto 

Program (NDOP)

The NDOP leads the effort to complete 

and maintain national coverage by 

orthoimagery with a resolution that is 

1-m or finer. The NDOP is a consortium 

of Federal and State agencies, principally 

the USGS, Farm Service Agency 

(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, 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.

Data Availability and Plans

The orthoimagery maintenance plan 

consists of two approaches:

Files of 1-m resolution, leaf-on, digital 

orthoimagery are acquired through 

the FSA NAIP; leaf-off orthoimagery 

requirements are acquired through the 

USGS. Both acquisitions focus on 

partnerships with Federal, State, and 

local agencies in order to combine 

resources. Files of 1-m NAIP imagery 

are collected on a 5-year cycle, whereas 

files of 1-m leaf-off imagery are acquired 

as requirements dictate.

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, will be 

available through:

• Geospatial One-Stop (http://gos2.

geodata.gov/wps/portal/gos), a 

web-based portal for one-stop 

access to geospatial data and 

• Seamless Data Distribution Service 

(http://seamless.usgs.gov/website/

Seamless/), a web-based site for 

viewing and downloading no-cost, 

public-domain data. 

Orthoimagery data also are accessible 

from the USGS by contacting any 

Science Information and Library Services 

office. 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 

archiving or disseminating the data is 

part of a cooperative agreement. Rather, 

USGS will rely on those agencies to 

make their orthoimagery accessible on an 

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://www.

nationalmap.gov) 

• The NDOP site (http://www.ndop.

gov/data.html)

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 

“For More Information” at 

geography.usgs.gov/www/partners/

crreps.html.

Information

Further information about The National 

Map and orthoimagery is available from 

the National Geospatial Program, Mail 

Stop 511, USGS National Center, 12201 

Sunrise Valley Drive, Reston, VA 20192. 

For additional information about The 

National Map, visit the nationalmap.gov 

Web site.

For information on other USGS products 

and services, call 1-888-ASK-USGS, or 

visit the USGS Publications Warehouse 

at http://infotrek.er.usgs.gov/pubs/. For 

additional information, visit the USGS 

home page at www.usgs.gov.

Orthoimages are a source of updated feature content for The National Map (Fred, La.).