Remote Sensing Image Acquisition

1
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, 356-82

2
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

3
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

4
Aerial Cameras
Keystones Wild RC-10 mapping camera
A large format oblique camera
5
Aerial photos

• Black White - single panchromatic layer
• Color 3 layers B-G-R
• Color IR 3 layers G-R-NIR

6
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)
High-altitude aerial photos
for the conterminous U.S. (1980 - 1989). 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
7
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

8
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
  spectro-radiometer measuring radiant flux in
  specific spectral wavebands

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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

10
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 CCDs 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

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3 different scanner designs
Single detector CCD-Scan Mirror TM
Pushbroom scanner SPOT
Two dimensional Staring Array Space Imaging
Original Current
Future
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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

13
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
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Remote Sensing Satellites in Space How do they
get there?
http//visibleearth.nasa.gov/cgi-bin/viewrecord?49
2
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MODIS Terra Launches
http//visibleearth.nasa.gov/cgi-bin/viewrecord?13
5
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Types of satellite orbits

• Geostationary Polar

700-900 km
35,800 km
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Polar Orbitting Satellite
http//visibleearth.nasa.gov/cgi-bin/viewrecord?13
4
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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
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Many different systems - which to choose?
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• 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

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AVHRR

• Thermal AVHRR provides water temperature data
• 3 bands in TIR

Gulf Stream
22
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/a
vhrrbrs_main.html
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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

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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/LAND_BIO/G
  LBDST_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 gt button. You can go
  more slowly by clicking on the gt button.

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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 gt 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?

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Can you see the Green Wave?
http//daac.gsfc.nasa.gov/CAMPAIGN_DOCS/LAND_BIO/G
LBDST_Images.html
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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.

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North America Close-up
http//daac.gsfc.nasa.gov/CAMPAIGN_DOCS/LAND_BIO/G
LBDST_Images.html
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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/

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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/
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MODIS TERRA in Orbit
http//visibleearth.nasa.gov/cgi-bin/viewrecord?13
3
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• 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 lt 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_hom
  epage/mission_profiles/instruments/MODIS.php

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• 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_homepag
  e/mission_profiles/instruments/ASTER.php

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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 Earths 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/
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ERTS-1

• Earth Resources Technology Satellite-1
• Renamed Landsat Multispectral scanner (MSS)
• First images in late 1972
• Was the first civil remote sensing satellite

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Landsat MSS bands 4 and 5
GREEN
RED
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Landsat MSS bands 6 and 7
Note water absorbs IR energy-no returnblack
INFRARED 2
INFRARED 1
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MSS color composite
Manhattan
Rutgers

• combining bands creates a false color composite
• redvegetation
• light blueurban
• blackwater
• pinkagriculture

Philadelphia Pine barrens Chesapeake
Bay Delaware River
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Landsat 4-5 Thematic Mapper (TM)
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Cross-track scanning system
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Landsat TM-7 bands-8 bit data
Spectral (where we look) Radiometric (how finely
can we measure the return) 0-63, 0-255, 0-1023
Landsat TM BAND 1 2 3 4 5
7 6
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Spectral wavebands of Landsat TM
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Landsat TM each waveband provides different
information about earth surface features
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Thermal imagery-temperature
Water analysis-nuclear power cooling ponds)
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Commercialization of Landsat

• Landsat was commercialized by Pres. Reagan
• EOSAT formed
• sales dropped

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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/
  

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• 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

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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
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SPOT before launch
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SPOT ground stations
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SPOT 41st images taken March 31, 1998
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Polar Sun synchronous orbit
2 side-by-side HRV sensors
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SPOT has steerable mirror
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Stereo imaging
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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

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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/ind
  ex.htm

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IKONOS SAMPLE IMAGERY
Multi-spectral 4m GRC
Pan-chromatic 1m GRC
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Space Imaging IKONOS Imagery Sample Bound Brook
NJ
1 m panchromatic
4 m multi-spectral
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• 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

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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 2.5-meter resolution.
• The satellite will operate in a 450-km 98-degree
  sun-synchronous orbit, with each orbit taking
  93.4 minutes
• http//www.digitalglobe.com/index.shtml

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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 7
bands 8 bit 14
days 185 Km .45-.52,
.52-.6, .63-.69, (0-255)
.76-.9, 1.55-1.75,
10.4-12.5, 2.08-2.3 um SPOT P
10 meters 1 band
8 bit 26 days
60 Km .51-.73 um
(0-255) (2 out of 5) SPOT X 20
meters 3 bands 8 bit
26 days 60 Km
.5-.59, .61-.68, .79-.89 um (0-255)
(2 out of 5) IKONOS 1 and 4 meters
1 and 4 bands 10
bit 1-2 days
11 km .45-.9, .44-.51,
.52-.60, (0-1023)
.63-.70, .76-.85
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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 (lt20) ETM image for
Middlesex County, NJ. What is the Scene ID,
Path/Row and date?
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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?
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Good Bye from Planet Earth
Source http//visibleearth.nasa.gov/