Upload
amy-atkinson
View
216
Download
0
Tags:
Embed Size (px)
Citation preview
Landsat
GEO 420Remote Sensing
Quiz #2
• 5_atmosphere.ppt
• 6_spectralsigs.ppt
• 7_sensors.ppt
• Sections 1.5 – 1.8 from Primary text
• Sections 2.1 – 2.6 from Primary text
• L&K2 reading
History
• 1965, director of USGS, proposed idea of
remote sensing satellite program to
gather data about natural resources of
planet.
– Conceived largely as a direct result of the
early Mercury photography of Earth.
• Weather satellites monitoring atmosphere were
considered useful, but no appreciation of terrain
data until mid-1960s.
• When Landsat 1 was proposed, it was met with
intense opposition.
• DoD feared a civilian program like Landsat would
compromise secrecy of reconnaissance
missions.
• 1965 - NASA began R.S. of Earth using sensors on planes.
• 1966 - USGS convinced Secretary of the Interior (Stewart Udall) to
announce that Dept. of the Interior (DOI) was going to proceed with
Earth-observing satellite program.
• This political stunt coerced NASA to expedite the building of
Landsat.
• But, budgetary constraints and sensor disagreements between
agencies (Dept. of Agriculture and DOI) held up satellite
construction.
• Finally, 1970, NASA had green light to build satellite.
• Within only two years, Landsat 1 was launched, heralding a new
age of remote sensing of land from space.
• 1975, NASA Administrator predicted that if one space age
development would save the world, it would be Landsat
and its successor satellites.
– Since the early 1970s, Landsat has continuously and consistently
archived images of Earth
– data archive gives scientist the ability to assess changes in
Earth’s landscape.
• ~40 years - Landsat has collected spectral information
from Earth’s surface, creating a historical archive
unmatched in quality, detail, coverage, and length.
• “It was the granddaddy of them all, as far as starting the trend of
repetitive, calibrated observations of the Earth at a spatial
resolution where one can detect humankind’s interaction with the
environment”
• Landsat sensors have moderate spatial-resolution.
– Can’t see individual houses, but you can see large
objects such as forests or highways.
• important because it is coarse enough for global coverage,
yet detailed enough to characterize human-scale processes
such as urban growth.
Landsat Program• Joint effort of
– USGS
– NASA
• Purpose - Gather Earth resource data using series of satellites.
– repetitive acquisition of observations
– land masses, coastal boundaries, coral reefs
– NASA -responsible for developing and launching spacecrafts.
– USGS -responsible for flight operations, maintenance, data
processing/archiving, product generation, and distribution.
• 1972 – Landsat 1 launched
• 1999 – Launch of Landsat 7
• ~40 years of data - longest continuous record
of the earth's surfaces.
• Critical to land surface monitoring and global
change research.
• No other eos matches Landsat's combination of
synoptic coverage, spatial and spectral
resolution.
Landsat 1: MSS 1972–1978
Landsat 2: MSS 1975–1982
Landsat 3: MSS 1978–1983 added thermal band but it failed
Landsat 4: MSS, TM (7 bands) 1982–2001* data downlink failed in 1993
Landsat 5: MSS, TM 1984–2012 (28 years, 10 months)
Landsat 6: MSS, ETM failed launch, 1993
Landsat 7: ETM+ 1999–still operational
Landsat 8: ETM+ Launch Feb. 11 2013
Landsat-1 & 2
Objective: To demonstrate the
usefulness of remote sensing data for
land and resource applications.
Design life of one year.
Multispectral Scanner
• Measured reflected energy in 4 spectral
bands.
• Landsat 3 - MSS sensor with additional
band in thermal (heat) infrared radiation.
MSS Bands
Band micron resolution
4 0.5-0.6 68 m x 83 m
5 0.6-0.7 68 m x 83 m
6 0.7-0.8 68 m x 83 m
7 0.8-1.1 68 m x 83 m
8 10.41-12.6 68 m x 83 m
Photo: Thematic Mapper
(TM), second-generation
sensor for
monitoring Earth's
resources.
Landsat 4, 5, & 7
Sensors
• MSS and TM sensors primarily detect
reflected radiation from Earth's
surface in vis and IR.
• But the TM sensor with its seven
spectral bands provides more
radiometric information than the MSS
sensor.
Sensors
• Sensors have evolved – MSS, TM,
Enhanced Thematic Mapper Plus (ETM+)
• Primary new features on Landsat 7 are
addition of band 8:
– panchromatic band with 15m spatial
resolution
• Panchromatic: sensitive to all or most of the visible spectrum.
– thermal IR channel with 60m spatial
resolution
• panchromatic band 8 covers 0.52-0.92 µm
– extends over band 2 (0.525-0.605 µm), band 3
(0.630-0.690 µm) and band 4 (0.750-0.900 µm).
– Pixel size 15 m
– Used for high-spatial-resolution analysis.
Landsat 7 and TM & ETM+ Characteristics:
Band Spectral Range(µm) Resolution(m)
1 .45 to .51 30
2 .525 to .605 30
3 .63 to .690 30
4 .75 to .90 30
5 1.55 to 1.75 30
7 2.09 to 2.35 30
6 10.40 to 12.5 60
8 .52 to .90 15
Landsat 8 (Landsat Data Continuity Mission) – 2013
Landsat Data Continuity Mission – 2013landsat.usgs.gov/L8_band_combos.php – compare Landsat 7 to Landsat 8
Landsat 1: MSS 1972–1978
Landsat 2: MSS 1975–1982
Landsat 3: MSS 1978–1983 added thermal band but it failed
Landsat 4: MSS, TM (7 bands) 1982–2001* data downlink failed in 1993
Landsat 5: MSS, TM 1984–2012 (28 years, 10 months)
Landsat 6: MSS, ETM failed launch, 1993
Landsat 7: ETM+ 1999–still operational
Landsat 8: ETM+ Launch Feb. 11 2013
Near Polar/Sun-synchronous orbits
Repeat coverage interval: 16 days (233 orbits)
Ground System
• Capable of capturing and processing 250
Landsat scenes and delivering 100 scenes
to users each day.
BenefitsMission Continuity: Landsat 7 - latest in long history of land
remote sensing spacecraft, spanning 40 years of
multispectral imaging.
Global Mission: data acquired systematically to build and
periodically refresh a global archive of sun-lit, substantially
cloud-free images of the Earth's landmass.
Benefits
Earth's landmass imaged every 16 days - using
a planning scenario that emphasizes
seasonal changes in vegetation and uses
cloud predictions from the National Weather
Service to avoid imaging cloudy areas, thus
optimizing the data acquisition strategy.
Benefits
Affordable Data Products: Landsat
products available from the EROS Data
Center for free.
Color Composites in Landsat TM Data
• Three-band composites created using the measured
reflected energy three spectral bands.
• The way in which the bands are mapped to the three
colors in the output image depends on what information is
desired to be highlighted in the image.
• For some applications, desirable for landcover classes to
be associated with familiar colors, e.g., grass is green.
• In other cases, contrasting colors are preferred to highlight
objects of interest from the background.
7 TM Bands
Color Composites in Landsat TM Data
True-Color Composite (3,2,1)• approximates range of vision for human eye• images appear as we would expect to see in
photograph. • low in contrast, somewhat hazy - blue light more
susceptible to scattering by atmosphere.• Broad-based analysis of underwater features and
landcover are applications for true-color composites.
• Band 3 (Visible red) = red • Band 2 (Visible green) = green • Band 1 (Visible blue-green) = blue
Color Composites in Landsat TM Data
Near Infrared Composite (4,3,2)• Add near infrared (NIR) band and drop visible
blue band. • Vegetation in the NIR band is highly reflective• NIR composite vividly shows vegetation in
various shades of red. • Water appears dark, almost black, due to the
absorption of energy in the visible red and NIR bands.
Band 4 (NIR) = red
Band 3 (Visible red) = green
Band 2 (Visible green) = blue
Color Composites in Landsat TM Data
• Shortwave Infrared Composite (7,4,3 or 7,4,2)• contains at least one shortwave infrared (SWIR)
band. • Reflectance in the SWIR region is due primarily
to moisture content.• SWIR bands are especially suited for change
detection, disturbed soils, soil type, and vegetation stress.
• Band 7 (SWIR) = red • Band 4 (NIR) = green • Band 3 (red) = blue
Or...• Band 7 (SWIR) = red • Band 4 (NIR) = green
• Band 2 (green) = blue
vegetation - shades of green.
Bare soils and clearcut areas - purplish or magenta.
bright red area is an active fire.
smoke plume originating from active fire site appears faint bluish.
Oil Spill in the Gulf of Mexico - Landsat 7
Station Fire - August 30, 2009 - 140,000 acres burned in Angeles National Forest - Mt. Wilson Observatory threatened. Blue and white haze is smoke, pinkish areas have been burned, active fires appear bright red.
Landsat-7 ETM+
Striping caused by
failure of scan line
corrector in 2003,
introduced major
striping in ETM+
imagery.
Landsat 5 image - Esperanza Fire in San Bernardino National Forest, Oct. 26, 2006. The fire caused a huge smoke plume; reaching ~3.0 miles high. Large image is a natural-color composite, small inset is false-color composite. The active fire fronts in the false-color image appear bright yellow.
Two false-color Landsat 5 images (1984 and 2009). ]dark purple grid of city streets and green of irrigated vegetation.
Images were created using reflected light from the shortwave infrared, near-infrared and green portions of the electromagnetic spectrum (Landsat 5 TM bands 7,4,2)
Venice - Landsat 7 - 2001. pan-sharpened false-color composite of ETM+ bands 7, 5, and 3. Venice can be found on Landsat WRS-2 Path 192 Row 28.
Climate Change - Lake Chad borders Chad, Niger, Nigeria, and Cameroon, as well as on a natural border, the Sahel: a grassland which divides the Sahara Desert to the north and the more humid savannah to the south. Because Lake Chad is a shallow lake, depths of 16 - 26 feet, its surface area fluctuates markedly with changes in climate.
Wisconsin tornado damage - Landsat 2007. natural-color image.
Accessing Landsat Data
Accessing Landsat Data – path 40 row 36