Transcript Remote Sensing Image Acquisition

Remote Sensing Image
Acquisition
Supplement to Lecture 1
material prepared by R. Lathrop 9/99
updated 8/03
includes slides previously prepared by S. Madry
and C. Colvard
Readings:
ERDAS Field Guide 5th Ed. Ch 1, 3:56-82
Digital Image Acquisition
• Digitization of analog aerial photography,
can be very useful for historical studies
and/or for high spatial resolution needs
• Direct acquisition using some form of
digital imaging sensor
Early attempts
• Kite system acquired
aerial photos of the
great San Francisco
earthquake and fire
• Pigeon cameras
• The development of
aircraft
• World Wars I and II
Aerial
Cameras
A large format oblique
camera
Keystone’s Wild RC10 mapping camera
Aerial photos
• Black & White single panchromatic
layer
• Color: 3 layers
B-G-R
• Color IR: 3 layers
G-R-NIR
USGS Aerial Photo Products
Aerial Products
Description
National Aerial Photography Program (NAPP)
Recent,high-quality aerial photos covering the conterminous U.S. on five- to
seven-year cycles (1987 - present).
National High Altitude Photography (NHAP)
altitude aerial photos for the conterminous U.S. (1980 - 1989).
High-
Digital Orthophoto Quadrangles (DOQs)
Digital images of aerial photos which combine the image characteristics of the
photo with the georeferenced qualities of a map (1987 - present).
Space Acquired Photography
Photos taken from the International Space Station (ISS), Shuttle, Skylab, Gemini,
and Apollo missions (1965 - present).
For more info: http://edc.usgs.gov/products/aerial.html
Analog Image Digitization
• Scanning micro-densitometer
• Linear array charge-coupled device
e.g., flat-bed scanners
• Area array charge-coupled device
e.g., digital camera
Remote Sensing Systems Instrumentation
• Radiometer - electro-optical instrument
measuring radiant flux (energy)
• Spectroradiometer - instrument that
measures radiant flux as a function of
wavelength - often as a continuous spectra
• Multispectral scanner - imaging spectroradiometer measuring radiant flux in
specific spectral wavebands
Major Elements of electro-optical
scanners
• Optical system: lenses, mirrors, apertures,
modulators & dispersion devices
• Detectors: provide an electrical signal
proportional to the irradiance on its active
surface, generally some type of
semiconductors
• Signal Processor: performing specified
functions on the electrical signal to provide
the desired output data
Electro-optical scanners
• Elements sensitive to electro
magnetic energy (EME) of
certain wavelengths focus
energy onto a sensor plane.
A prism is used to divide
the energy into specific
wavelengths. The CCD’s
are stimulated and produce
an electrical signal equal to
the energy focused upon it.
These data are recorded.
• Data are converted from an
analog electrical signal to a
digital number
3 different scanner designs
Single detector
CCD-Scan Mirror
TM
Original
Pushbroom scanner
SPOT
Current
Future
Two dimensional
Staring Array
Space Imaging
Important imaging parameters
• The Instantaneous Field of View (IFOV)
subtends an area on the terrain called a
Ground Resolution Cell (GRC)
• The Angular Field of View determines the
width of the Ground Swath
• The Dwell Time, the time required for the
detector IFOV to sweep across the GRC
Airborne Remote Sensing
Aircraft Scanners Digital imagery acquired from several
multispectral scanners on board NASA ER-2, NASA C-130B,
and NASA Learjet aircrafts (1982 - 1995).
For more info: http://edcdaac.usgs.gov/airborne/air_scan.html
Digital Cameras increasingly aerial imagery is being
acquired through digital camera framing systems that can
collect multispectral (VIS-NIR) imagery and be quickly
corrected through GPS-based navigational systems to produce
digital orthophotographic imagery in near-real time
Remote Sensing Satellites in Space:
How do they get there?
http://visibleearth.nasa.gov/cgi-bin/viewrecord?492
MODIS Terra Launches
http://visibleearth.nasa.gov/cgi-bin/viewrecord?135
Types of satellite orbits
• Geostationary
Polar
700-900 km
35,800 km
Polar Orbitting Satellite
http://visibleearth.nasa.gov/cgi-bin/viewrecord?134
Geostationary vs. polar orbiting sensors
Geostationary sensors
orbit with the earth
continually viewing the
same hemispheric area
Polar orbiters,
continually view new
areas of the earth as the
planet rotates underneath
the sensor. Keeps the
same general solar time
as it cross the equator on
each orbit - called sun
synchronous
Polar
orbit
Many different systems - which to choose?
• AVHRR-Advanced Very High Resolution
Radiometer
• Polar orbit, coarse spatial resolution: 1 and 4 km
cells, broad 2400 km ground swath width
• 2 operational now-1 day and 1 night pass for each
AVHRR
• Thermal
AVHRR
provides
water
temperature
data
• 3 bands in
TIR
Gulf Stream
Remote Sensing of the Earth:
Clues to a Living Planet
• Scientists at the NASA Goddard Space Flight
Center have used the AVHRR to create maps of
vegetation greenness for the entire globe
• The NASA scientists have combined numbers of
satellite images to create a composite picture of
the earth at approximately biweekly intervals over
a number of years
For more info and images, go to:
http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/BRS_SRVR/avh
rrbrs_main.html
Global AVHRR composite
• 1 band in the Red:
.58-.6 um
• 1 band in the NIR:
.72-1.1 um
• Vegetation Index
to map vegetation
amount and
productivity
Remote Sensing of the Earth:
Clues to a Living Planet
• You can access these images over the INTERNET
• http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/LA
ND_BIO/GLBDST_Images.html
• You can either browse through individual images
or watch an animation
• First, click on the Global 1 degree 1986 NDVI
(Climate Data Set) (1.5 MB Quicktime)
animation. Open it, and click on the > button. You
can go more slowly by clicking on the |> button.
Remote Sensing of the Earth:
Clues to a Living Planet
• First, click on the Global 1 degree 1986 NDVI
(Climate Data Set) (1.5 MB Quicktime)
animation. Open it, and click on the > button.
• Watch closely, can you observe the Green Wave
in the northern hemisphere?
• What about the Brown Wave?
• Now look at the southern hemisphere. What do
you observe?
Can you see the Green Wave?
http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/LAND_BIO/GLBDST_Images.html
Remote Sensing of the Earth:
Clues to a Living Planet
• Now take a look at the Northern hemisphere
in greater detail.
• Click on the North America 1986 NDVI
(750K quicktime) Animation.
• Can you find where you live? How long
does it stay green?
• Compare Florida with Maine or Minnesota.
North America: Close-up
http://daac.gsfc.nasa.gov/CAMPAIGN_DOC
S/LAND_BIO/GLBDST_Images.html
Remote Sensing of the Earth:
Clues to a Living Planet
• To access more recently acquired AVHRR
imagery go to the National Oceanographic
& Atmospheric Administration (NOAA)
Satellite Active Archive
http://www.saa.noaa.gov/
After a picture-perfect launch into space December 1999, Terra
Began releasing images April 2000. Terra includes MODIS, a 2nd
generation “AVHRR-like” instrument, with a number of potential
applications in regional to global scale environmental monitoring
of the land, ocean and atmosphere. Also includes ASTER,
CERES, MISR and MOPITT.
For more info go to:
http://terra.nasa.gov/
MODIS TERRA in Orbit
http://visibleearth.nasa.gov/cgi-bin/viewrecord?133
•36 discrete bands between 0.4 and 14.5 µm
•spatial resolutions of 250, 500, or 1,000 m at nadir.
•Signal-to-noise ratios are greater than 500 at 1-km resolution (at a solar zenith angle of
70°), and absolute irradiance accuracies are < ±5% from 0.4 to 3 µm (2% relative to the
sun) and 1 percent or better in the thermal infrared (3.7 to 14.5 µm).
•MODIS instruments will provide daylight reflection and day/night emission spectral
imaging of any point on the Earth at least every 2 days, operating continuously.
•For more info:
http://eospso.gsfc.nasa.gov/eos_homepage/mission_profiles/instruments/MODIS.php
•3 visible/NIR(VNIR: 0.5 and 0.9 µm) with 15-m resolution
•3 mid IR (SWIR: 1.6 and 2.43 µm) with 30-m res.
•5 TIR (8 and 12 µm) with 90-m resolution
•60- km swath whose center is pointable cross-track ±8.55° in the SWIR and TIR,
with the VNIR pointable out to ±24°. An additional VNIR telescope (aft pointing)
covers the wavelength range of Channel 3. By combining these data with those for
Channel 3, stereo views can be created, with a base-to-height ratio of 0.6.
•Overpass every 16 days in all 14 bands and once every 5 days in the three VNIR
channels.
For more info:
http://eospso.gsfc.nasa.gov/eos_homepage/mission_profiles/instruments/ASTER.php
“Aqua,” Latin for “water,” is a NASA Earth
Science satellite mission named for the
large amount of information that the
mission will be collecting about the Earth’s
water cycle, including evaporation from the
oceans, water vapor in the atmosphere,
clouds, precipitation, soil moisture, sea ice,
land ice, and snow cover on the land and
ice.
Additional variables also being measured by Aqua include
radiative energy fluxes, aerosols, vegetation cover on the land,
phytoplankton and dissolved organic matter in the oceans, and
air, land, and water temperatures.
The AQUA Platform includes the MODIS, CERES and AMSR_E
instruments. Aqua was formerly named EOS PM, signifying its
afternoon equatorial crossing time. AQUA was launched May
2002. For more info: http://aqua.nasa.gov/
ERTS-1
• Earth Resources
Technology
Satellite-1
• Renamed Landsat
Multispectral
scanner (MSS)
• First images in late
1972
• Was the first civil
remote sensing
satellite
Landsat MSS bands 4 and 5
GREEN
RED
Landsat MSS bands 6 and 7
Note: water absorbs IR energy-no return=black
INFRARED 1
INFRARED 2
MSS color composite
Manhattan
Rutgers
• combining bands
creates a false color
composite
• red=vegetation
• light blue=urban
• black=water Philadelphia
Pine barrens
Chesapeake
Bay
Delaware River
• pink=agriculture
Landsat 4-5 Thematic Mapper (TM)
Cross-track scanning system
Landsat TM-7 bands-8 bit data
Spectral
Landsat TM BAND
(where we look)
Radiometric
(how finely can we
measure the return)
0-63, 0-255, 0-1023
1
2
3
4
5 7
6
Spectral wavebands of Landsat TM
Landsat TM: each waveband provides
different information
about earth surface features
Thermal imagery-temperature
Water analysis-nuclear power cooling ponds)
Commercialization of Landsat
• Landsat was
commercialized
by Pres. Reagan
• EOSAT formed
• sales dropped
Landsat 7
• 15 m ETM+ (enhanced TM) sensor
• April 1999 launch
• Oct.’92 Land remote sensing policy
act
• a panchromatic band with 15m spatial
resolution-fully coregistered w/30m
• on-board, full aperture, 5% absolute
radiometric calibration
• a thermal IR channel with 60m
spatial resolution
•for more info go to: http://landsat.gsfc.nasa.gov/
• French commercial
remote sensing system
• First launch in 1986
• 10 and 20 m spatial
resolution
• 60 km swath width
• Stereo viewing ability
• Will have 2.5 m in
1999
Panchromatic (PAN) sensor: 10 m GRC
Pan 0.51-.73 um
High Resolution Visible (HRV) sensor: 20m GRC
G (.5-.59), R (.61-.68), NIR (.79-.89)
Ground Swath Width of 60 km
For more info go to: http://www.spotimage.fr/home/home.htm
SPOT before launch
SPOT ground stations
SPOT 4
1st images taken March 31, 1998
Polar Sun synchronous orbit
2 side-by-side
HRV sensors
SPOT has steerable mirror
Stereo imaging
Indian Remote Sensing (IRS)
satellite
•
•
•
•
•
IRS-1C launched in December 1995
IRS1D launched in September 1997
Panchromatic: 0.5-0.75 um
5.8 m GRC, 30 km ground swath
22 day repeat cycle with off-nadir
pointability
Space Imaging IKONOS
• Panchromatic (045-0.9 um): 1 m
• Multispectral: 4 m
Blue (445-516nm), Green(506-595nm)
Red (632-698nm) NIR (757-853nm)
• 11 km swath width
• Pointable to 45o for daily viewing
• For more info go to:
http://www.spaceimage.com/index.htm
IKONOS SAMPLE IMAGERY
Multispectral
4m GRC
Panchromatic
1m GRC
Space Imaging IKONOS Imagery
Sample: Bound Brook NJ
1 m panchromatic
4 m multi-spectral
OrbView-3
•Panchromatic: 1 m
•Multispectral (color): 4 m
• Pointable: anywhere on globe within 3 days
•Additional hyperspectral sensor
•For more info go to:
http://www.orbimage.com/index.html
Quickbird
•DigitalGlobe™ successfully launched its QuickBird
satellite on the Boeing Delta II launch vehicle on October
18, 2001.
•Panchromatic: 0.61-1m
•Multispectral (color): 2.5-4 m
•Can increase the resolution system by adjusting the
orbit in which the satellite is flown. As a result,
panchromatic resolution increases from 1 meter to 61
centimeters and multi-spectral increases from 4- to 2.5meter resolution.
•The satellite will operate in a 450-km 98-degree sunsynchronous orbit, with each orbit taking 93.4 minutes
http://www.digitalglobe.com/index.shtml
Different sensors and resolutions
sensor
spatial
spectral
radiometric temporal
---------------------------------------------------------------------------------------------------------------AVHRR
1.1 and 4 KM 4 or 5 bands
10 bit
12 hours
2400 Km
.58-.68, .725-1.1, 3.55-3.93 (0-1023) (1 day, 1 night)
10.3-11.3, 11.5-12.5 (micrometers)
Landsat MSS
80 meters
4 bands
6 bit
16 days
185 Km
.5-.6, .6-.7, .7-.8, .8-1.1
(0-63)
Landsat TM
30 meters
185 Km
SPOT P
10 meters
60 Km
7 bands
.45-.52, .52-.6, .63-.69,
.76-.9, 1.55-1.75,
10.4-12.5, 2.08-2.3 um
1 band
.51-.73 um
SPOT X
20 meters
60 Km
IKONOS
1 and 4 meters
11 km
8 bit
(0-255)
14 days
8 bit
(0-255)
26 days
(2 out of 5)
3 bands
.5-.59, .61-.68, .79-.89 um
8 bit
(0-255)
26 days
(2 out of 5)
1 and 4 bands
.45-.9, .44-.51, .52-.60,
.63-.70, .76-.85
10 bit
(0-1023)
1-2 days
Homework 1: Selecting and Ordering Imagery
1. Enhanced Landsat Thematic Mapper 7 (ETM+) imagery is
available through the U.S. Geological Survey. Go to the USGS’
Earth Explorer web site (http://edcsns17.cr.usgs.gov/EarthExplorer/)
or their newer, better web browser (http://glovis.usgs.gov).
A. How many Landsat TM scenes are needed to image the entire
state of New Jersey?
B. What are the Path/Row numbers?
C. What is the cost per square km for the ETM+ Level 1G image?
Hint: 1st determine the area of the scene in km2, then divide scene
cost by area
D. Using the Search Archive capabilities, determine the date of the
most recent cloud-free (<20%) ETM+ image for Middlesex County,
NJ. What is the Scene ID, Path/Row and date?
Homework 1: Selecting and Ordering Imagery
2. The OrbImage Corporation (www.orbimage.com/) markets
OrbView and other high resolution imagery. Access the
OrbImage site to get up-to-date information on pricing and
availability.
A. What is the spatial accuracy and cost per square kilometer for
the standard OrbView Cities product? OrbView Cities Plus?
3. DigitalGlobe (www.digitalglobe.com) markets Quickbird
imagery. Access the DigitalGlobe site to get up-to-date
information on pricing and availability?
A. What types of Quickbird image products are offered?
Good Bye from Planet Earth
Source http://visibleearth.nasa.gov/