U.S. Department of Commerce

National Oceanic and Atmospheric Administration

National Ocean Service

National Geodetic Survey
U.S. Department of Commerce

National Oceanic and Atmospheric Administration

National Ocean Service

National Geodetic Survey

1999

William M. Daley

Secretary, U.S. Department of Commerce

D. James Baker, Ph.D.

Under Secretary of Commerce for Oceans and Atmosphere

Administrator, National Oceanic and Atmospheric Administration

Terry D. Garcia

Assistant Secretary of Commerce for Oceans and Atmosphere

Deputy Administrator, National Oceanic and Atmospheric Administration

Nancy Foster, Ph.D.

Assistant Administrator for Ocean Services and Coastal Zone Management

NOAA, National Ocean Service

Charles W. Challstrom

Director, National Geodetic Survey

To obtain further information, visit NOAA’s National Geodetic Survey web site at: 

http://www.ngs.noaa.gov 

or write to:

Director, National Geodetic Survey

NOAA, N/NGS

SSMC-3, #8657

1315 East-West Highway

Silver Spring, MD 20910-3282

William M. Daley

Secretary, U.S. Department of Commerce

D. James Baker, Ph.D.

Under Secretary of Commerce for Oceans and Atmosphere

Administrator, National Oceanic and Atmospheric Administration

Terry D. Garcia

Assistant Secretary of Commerce for Oceans and Atmosphere

Deputy Administrator, National Oceanic and Atmospheric Administration

Nancy Foster, Ph.D.

Assistant Administrator for Ocean Services and Coastal Zone Management

NOAA, National Ocean Service

Charles W. Challstrom

Director, National Geodetic Survey

To obtain further information, visit NOAA’s National Geodetic Survey web site at: 

http://www.ngs.noaa.gov 

or write to:

Director, National Geodetic Survey

NOAA, N/NGS

SSMC-3, #8657

1315 East-West Highway

Silver Spring, MD 20910-3282
Imagine bridges not meeting in the middle,

planes landing next to — rather than at — airports,

ships frequently running aground, and the northbound commuter train on the same track at the

same time as a south-bound freight.... And

imagine the Internet forever gridlocked.

This is just a glimpse of what our lives would

be like without geodesy. Geodesy is the science

of measuring the size and shape of the Earth and

precisely locating points, or coordinates, on the

Earth. These geodetic coordinates can tell us

exactly where we were, where we are, and where

we’ll be when we get there.

But the mere application of geodesy alone

doesn’t create order out of chaos. Geodesy

shapes our lives today through a combination of

three innovative tools:

■ the Global Positioning System (GPS), which

supplies the coordinates;

■ NOAA’s National Spatial Reference System

(NSRS), which gives the GPS coordinates

integrity; and

■ Geographic Information Systems (GIS), which

make the coordinates useful.

As our society and economy become increasingly dependent on complex technologies, the

need for precise positioning and consistent, reliable data intensifies. This imaginative trio of GPS,

NSRS, and GIS is providing the order needed for

ensuring public safety, enhancing economic

prosperity, and protecting environmental quality

throughout the nation.

2

“Geography without geodesy is a felony.”

–Gunther Greulich, Past President, 

American Congress on Surveying and Mapping

Life Without Geodesy—

Sheer Chaos! Sheer Chaos!
LEFT: More than 98 percent of the nation’s

tonnage in international commerce moves

by sea. Without accurate geodetic

information, nautical charts would be

fraught with errors, and accidents,

groundings, and spills of hazardous cargo

could become the rule rather than the

exception. (Photo: American President Lines)

BELOW: This dramatization of construction

of a bridge across a large intercoastal

waterway demonstrates how chaotic our

lives would be not only without geodesy

but without NOAA’s National Spatial

Reference System. Geodetic data on the

mainland came from one source, while

the data on the barrier islands came from

another.... And never the twain shall

meet! (Photo: Zurich U.S.)

3
The Global Positioning System (GPS) is a constellation of 24 satellites that transmit signals to

receivers throughout the world. With this system,

it’s possible to assign every point on Earth its own

unique address — its latitude, longitude, and height.

For example, the coordinate counterpart of 18

Poplar Street might be 40 degrees 35 minutes 20

seconds N by 78 degrees 00 minutes 30 seconds

W by 60 meters. NOAA’s National Spatial Reference System provides a consistent framework for

identifying those GPS coordinates. Each feature

of the property at 18 Poplar — the house, the

underground oil tank, the sewer line — has its

own coordinate address. Fortunately, we won’t

have to remember all those coordinates, since

our technologies will do that for us.

Complementing this space-based system is a

growing multi-agency network of Continuously

Operating Reference Stations (CORS). These

ground stations provide real-time navigation

information 24 hours a day, 7 days a week, to

guide our transportation and communications

systems and manage our natural resources. As a

major component of NOAA’s National Spatial

Reference System, the CORS network corrects

GPS satellite signals to accuracies within 1/32 of an

inch, and then distributes the corrected data to

users.

Standard civilian GPS can tell us which field a

football is on. With CORS we can determine

which yard line and, sometimes, which blades of

grass the ball is on. NOAA sets the standards 

for CORS stations, processes the standardized

satellite observations, ensures the quality of the

stations’ positional accuracy and operation, and

makes the data available to users.

4

“The National Geodetic Survey, under NOAA, 

effectively launched our industry.”

– Charles Trimble, Chair, U.S. GPS Industry Council

A Space-Age Address—

For Your Home... 

and Your Mailbox

For Your Home... 
Where we were...

LEFT: Before the advent of satellite

technology, NOAA line-of-sight surveys

were made at night with a theodolite, an

instrument combining a telescope with a

way to measure angles accurately. Temporary towers

were built directly over the geodetic control points,

which were brass disks set in concrete, similar to the one

shown above, to the right. From the top of each tower,

NOAA surveyors would observe lights set on top of the

other towers, and then compute the coordinates of the

control points. (Photos: National Geodetic Survey)

5

...and where we are.

RIGHT: With GPS, a survey that once

took days can now be completed in a

few hours, with 10 to 100 times more

accuracy. GPS satellites beam signals in

real time to GPS receivers, like the one

shown here, revealing their coordinates

— exactly where they are in space at

any given time. With that information,

a microprocessor in the receiver can

calculate the receiver’s position. 

(Photo: William Stone)

INSET: Like calculators, GPS equipment

is becoming less expensive with time.

Hand-held devices are available today

for under $200. (Photo: William Stone)
The World 

at Your Fingertips

America’s 95,000 miles of coastline are subject

to natural and man-made processes that continually alter its shape and character. The accuracy,

consistency, and currency of our national shoreline need to be frequently ensured, especially

during this era of rapid coastal development.

Countless applications depend on NOAA’s

National Spatial Reference System to determine

where the land meets the sea, including:

■ producing state-of-the-art nautical charts for

safe, efficient, and competitive maritime commerce;

■ defining America’s marine territorial limits;

■ constructing safe buildings, roads, and bridges;

and 

■ delineating property lines to minimize boundary disputes.

NOAA has led the way in developing new

applications for GPS. For example, using GPS

with aerial photography, we can locate any point

on the land below to within about a foot.

The remarkable efficiencies made possible by

such precise positioning data can be magnified by

feeding the data into a Geographic Information

System (GIS). A GIS assembles information from a

wide variety of sources, including ground surveys,

existing maps, and aerial photos. In a GIS, specific

information about a place — such as the locations

of utility lines, roads, streams, and buildings — is

layered over a set of geodetic control. With a computer, regional planners can use the layers individually or in various combinations — for example, to

determine how to improve traffic flow, merge construction with existing utility systems, or protect

the public from potential natural disasters. And

because a GIS stores data digitally, information

can be quickly and economically updated, easily

reproduced, and made widely available.

6

“The world is but a canvas to our imagination.” 

–Henry David Thoreau

The World 

at Your Fingertips
7

This high-accuracy NOAA photo, taken in 1997,

clearly shows radical changes in the port’s

shoreline during the 43-year period.

This aerial photo of the Port of Long Beach was

taken in 1954 as the basis for depicting the land

features on NOAA’s nautical charts.

The first step in assembling

a GIS involves creating a

foundation “layer” of

virtual geodetic control,

shown above as . These

reference points serve as

the basis — the “brass

tacks” —for successive data

layers, such as land and

water boundaries.

In a stepwise fashion, additional layers are each referenced to NOAA’s National

Spatial Reference System.

Here, the base geodetic

control layer, plus the land

and water demarcations,

are used as a “backdrop” for

additional features, such as

roadways.

A bathymetric layer

depicting the contours of

the ocean bottom serves a

variety of purposes, such as

showing ships’ captains the

location of the deepest

waters and indicating where

marine life and habitats

may need special protection.
A Seamless System for 

America’s Infrastructure

Most of the nation’s infrastructure — our

transportation, utility, energy, and communications

systems — depends on the teamwork provided 

by GPS, GIS, and the National Spatial Reference

System.

Transportation

New-age geodesy is helping many U.S. transportation sectors to simultaneously reduce their

operational costs and increase their safety and

reliability. For example, this trio of tools:

■ Provides the essential foundation for our air

navigation and traffic management systems,

reduces fuel consumption by shortening flight

paths, and ensures smooth, safe take-offs and

landings.

■ Serves as a common reference between a

ship’s electronic chart and the real-time position of its keel in relation to the bottom of the

channel, thus promoting safe navigation and

reducing the idle time ships spend outside

ports waiting for ideal conditions.

■ Allows railroads to route cars seamlessly and

accurately in crowded shipping yards and to

maintain a safe distance between trains on the

same track.

■ Helps companies calculate the most direct

routes to their destinations for just-in-time

delivery.

Receivers connected to electronic map displays

are available to new car buyers today, and some

rental car companies are offering this technology

to their customers. In the not-too-distant future,

GIS will be a standard feature in automobiles.

Utilities and Energy Systems

Utility companies are using geodetic coordinates to compile maintenance data bases on ser8

“If you can dream it, you can do it.”

– Walt Disney

A Seamless System for 

America’s Infrastructure
9

ABOVE: The National Spatial Reference

System and GPS have made possible the

development of an improved air traffic

control system. Work is under way on

developing highly accurate zero-visibility

landing systems.

RIGHT: Some vessels today draw up to 60

feet of water — the equivalent of a fivestory building plunging toward the ocean

floor. Accurate spatial data can alert ships’

captains to shoals or other obstructions

they may find in their course. (Photo:

American Petroleum Institute)
vice equipment, such as underground pipes and

manholes. When a piece of equipment needs service, maintenance personnel can return to its

exact location, even if it’s below the street or

obscured by ground cover. If equipment is

changed or moved, its new location can be easily

updated in a GIS.

GPS, GIS, and the National Spatial Reference

System team up in all phases of coal, oil, and gas

exploration, extraction, and delivery. This trio of

tools is indispensable in designing, constructing,

and mapping pipelines and utility lines — especially gas lines, which can save lives as well as

millions of dollars.

In earth moving, mineral extraction, and construction projects, these tools help to simultaneously dispatch and route vehicles and to excavate

according to precise specifications and environmental regulations. They also aid in documenting

the land’s condition and topography before

excavation begins, so the area may be restored as

naturally as possible.

As groundwater is withdrawn from below the

Earth’s surface, the ground above settles. This

sinking, known as subsidence, can fracture roads

and building foundations and can burst water,

sewer, and gas lines. Through partnerships with

local agencies, NOAA is using GPS to measure

subsidence at a fraction of the cost of traditional

surveying methods.

Communications Systems

Automated teller machine (ATM) banking and

other financial transactions, voice communication, high-speed computing, and the Internet all

depend on precise timing.

Without the extremely accurate clocks within

the GPS satellites, the Internet would have gridlocked years ago and would never have achieved

anywhere near the utility it has today. The GPS

clocks, in turn, depend on the precise positioning

derived from NOAA’s National Spatial Reference

System.

Although GPS satellites broadcast correct timing information, the signal becomes susceptible

to errors during the eight-hundredths of a second it takes to travel up to 15,000 miles to the

receiver. Any error in the position of the receiver

causes errors in timing.

A packet of information on a fiber-optic cable

or a radio transmission will travel one foot in a

nanosecond, or a billionth of a second. Every foot

of error in the positions of the electronic message

transmission and receiving sites equals one

nanosecond of error in timing, increasing the

probability of collision and jamming.

As our communications become more

sophisticated and the use of new technologies

grows exponentially, nanosecond — even subnanosecond — timing dependent upon accurate

positioning becomes ever more critical.

10
11

RIGHT: Real-time GPS, an

on-board GIS, and

positions referenced to

the National Spatial

Reference System enhance

the efficiency of heavy

equipment and provide

enormous savings in time

and money in many

applications in mining,

construction, forestry,

agriculture, and public

services.

ABOVE: The cost of transporting goods across state lines would

increase significantly without the quality control inherent in

NOAA’s National Spatial Reference System. Because reliable

maps wouldn’t exist, truckers couldn’t determine the shortest

route to their destination — or worse, would frequently get lost.

LEFT: Using the tools provided by GPS, GIS, and NOAA’s

National Spatial Reference System, utility companies can

pinpoint the location of every piece of service equipment in an

area, even if it’s below the street or obscured by ground cover.
New Heights,

New Opportunities

NOAA’s leadership in establishing the National Spatial Reference System has been

key to the imaginative application of myriad new-age technologies. Its recently

launched Height Modernization effort, which will accelerate NOAA’s completion of the system’s network of vertical (height) coordinates, is setting the

stage for applications of tomorrow’s technologies. This NOAA aerial

photo of the San Francisco Bay area highlights how access to accurate, reliable, real-time height information can save time and

money and protect lives, property, and the environment.
Knowing the vertical

distance between a ship’s

bottom and the channel

floor minimizes ship

groundings, environmental damage, and

the time spent waiting for

ideal conditions to enter

or leave a port.

Knowing how

high an aircraft’s

landing gear is

above the

runway ensures

safe, smooth

landing, even in

zero-visibility

weather.

Knowing the vertical

distance between the

bottom of a bridge

and the top of a ship

allows captains to

navigate safely and

precisely and avoid

damaging the ship

and the bridge.

Knowing the changes

in heights of elevated

infrastructure can

help trigger warning

systems, alerting

motorists to the

potential collapse 

of roadways in an

earthquake.

Knowing the height of

the bulldozer blade with

respect to the coal pile

and loading equipment

helps prevent damage to

the conveyor belt and

costly delays in loading,

which are ultimately

paid for by consumers.
A Place in Space...

For Saving Lives

Local 911 emergency response systems are

relying on positioning derived from GPS and

NOAA’s National Spatial Reference System. Using

geodetic coordinates in a GIS, dispatchers can

quickly guide vehicles to their destination. GPS

receivers connected to map displays mounted on

the dashboards of emergency vehicles can guide

drivers to a specific address. Centralized routing

GIS displays depict evacuation routes and show

emergency response managers how their

resources are deployed.

One of several imaginative uses of GPS positioning technologies is in an automobile accidentalert system. When the system senses the vehicle’s

impact with an object, it automatically calls for

help and transmits the vehicle’s precise coordinates to emergency service providers.

Mayors, city planners, and community leaders

can consult information fed into a GIS — for example, to determine what areas are prone to fires and

whether several fires in an area might signal arson.

A GIS can tell police where a high number of accidents occur, suggesting potential problems with

the roads, lights, signs, or speed limits.

Measuring water vapor is essential for accurately forecasting storms. GPS provides the measurements needed for updating forecasts, works

continuously under all weather conditions,

doesn’t require calibration, and is inexpensive

when compared to other monitoring systems.

Flooding is by far the costliest of U.S. natural

disasters. The National Spatial Reference System

provides reliable elevation information for Flood

Insurance Rate Maps, which cover about 9 million

flood-prone buildings across the nation. GPS surveys enable models to accurately predict future

flood damages in or near a community’s designated flood hazard area.

14

“Reason can answer questions, 

but imagination has to ask them.”

– Ralph Gerard, American Physiologist

A Place in Space...

For Saving Lives
LEFT: Firefighters have

traditionally relied on street

addresses and landmarks to

report their positions. But in a

major disaster, these landmarks

may be destroyed or obscured

by smoke. Real-time geodetic

data can guide emergency

crews to disaster areas quickly,

accurately, and efficiently.

BELOW: GPS is a reliable, low-cost

technology for measuring water vapor,

which is essential to predicting storms.

LEFT: The extensive resurveying necessitated

by the 1994 earthquake in Northridge,

California, cost over $1 million. NOAA is

working with other federal agencies to

replace traditional labor-intensive, highcost line-of-sight survey procedures with

new cost-efficient GPS technology. 

(Photo: U.S. Geological Survey)

15
Producing More ...

Paying Less

NOAA’s National Spatial Reference System is

critical to our nation’s productivity and to the

conservation of our rich natural resources.

Following the 1989 EXXON Valdez spill, Congress mandated that response plans be practiced

by the entire oil spill response community. Central

to an exercise — and a real spill — are tracking and

predicting the movement of the waterborne oil

and estimating the likely environmental impacts.

NOAA’s coastal mapping, whose foundation is

the National Spatial Reference System, provides

information for managing cleanup activities,

characterizing marine habitats, and assessing

environmental damage.

Wetlands are disappearing at an alarming

rate, placing our ocean and coastal resources at

serious risk. By analyzing digital chart data using

the National Spatial Reference System, GPS, and

GIS, coastal managers can develop maps that

identify wetlands, local sources of pollution, and

other data critical to sustaining healthy coasts.

Some farms have 20 or more different soil

types within one field. Until recently, farmers have

addressed this variability by applying high rates

of chemicals to entire fields — a “one size fits all"

approach — because they couldn’t determine the

optimal application precisely enough on an acreby-acre basis. Precision farming uses NOAA’s

National Spatial Reference System, GPS, and GIS

to tailor applications of seed and chemicals to

small areas of land, decreasing both production

costs and the runoff of contaminants.

16

“We are harnessing power in the sky to chart a

prosperous new course on the ground.”

– Vice President Al Gore

Producing More ...

Paying Less
LEFT: Estuarine and coastal wetlands are

decreasing nationwide by an average of 31

square miles a year. GPS and GIS technologies

are helping coastal managers make more

informed decisions about fisheries programs,

stock assessment, algal blooms, and other

issues affecting the health and vitality of coastal

ecosystems. (Photos: Stephen C. Delaney, U.S.

Environmental Protection Agency)

LEFT: Using precision

farming techniques

based on geodetic

coordinates, farmers

can farm by the foot —

not by the field.

Computers in huge

spreader machines

guided by GPS

regulate the precise

amount and mix of

chemicals for every

square foot. (Inset

photo: U.S. Agricultural

Research Service)

RIGHT: Environmental sensitivity maps and spillresponse models help cleanup managers identify

the most vulnerable ecological areas near a spill

and predict how the spill will respond to weather,

current, and tide conditions. (Photo: U.S. Fish and

Wildlife Service)

17
Endless Possibilities 

for the 21st Century

NOAA’s National Geodetic Survey is working

to make what is only imagined today tomorrow’s

reality. Automatic construction equipment, selfguided automobiles, robotic cranes — these are

only a few of the endless possibilities awaiting us,

thanks to the reliable accuracy of GPS and

NOAA’s National Spatial Reference System.

NOAA’s plan for the new century is to work

closely with its partners to develop technologies

that advance the smart, efficient growth of our

economy, the prudent development of our natural resources, and the long-term sustainability

of our communities. NOAA’s National Geodetic

Survey will continue to imagine — and make real

— the possibilities of exciting new technologies

that will dramatically enhance our everyday lives

and our nation’s competitiveness in today’s

global economy.

18

“Anything one man can imagine, 

other men can make real.”

– Jules Verne

Endless Possibilities 

for the 21st Century
19