landsat geo 420 remote sensing. quiz #2 5_atmosphere.ppt 6_spectralsigs.ppt 7_sensors.ppt sections...

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