NON-PHOTOGRAPHIC SYSTEMS: Multispectral Scanners Medium...
Transcript of NON-PHOTOGRAPHIC SYSTEMS: Multispectral Scanners Medium...
NON-PHOTOGRAPHIC SYSTEMS: Multispectral Scanners
Medium and coarse resolution sensor comparisons:
Landsat, SPOT, AVHRR and MODIS
CLASSIFICATION OF NONPHOTOGRAPHIC REMOTE SENSORS
PASSIVE ACTIVE
SAR LASER DIGITAL CAMERA
VIDEO CAMERA
MULTI-SPECTRAL SCANNERS
MICROWAVE
THERMAL (e.g. TIMS)
VISIBLE & NIR HYPERSPECTRAL (e.g. AVIRIS)
ACROSS TRACK (sweep)
e.g. Landsat, AVHRR
ALONG TRACK (push)
e.g. SPOT
ACROSS-TRACK / MULTISPECTRAL SCANNING OPERATION
scan angle (IFOV)
pixel
scan lines
• An oscillating mirror scans across the
terrain at right angles to the flight path • mirrors direct the radiation from the IFOV to spectrum-separating devices which divide the signal into discrete bands or channels • the signal from each band is focused on detector elements that transform the radiation into an electrical signal, which is recorded and stored digitally
ALONG-TRACK SCANNING OPERATION
• linear array of CCDs “scan” perpendicular
to the flight line (no mirrors) • each CCD senses energy from a single ground resolution cell (pixel) • each spectral band (channel) requires its own CCD array • each scan line is viewed by all channel arrays simultaneously
• Advantages of along-track scanners
– linear arrays afford longer residence time for which to measure energy from each ground resolution cell, resulting in a stronger signal
– fixed relationship of CCDs along each scan line results in improved geometric integrity
– CCDs small in size and require less power for operation
– w/o moving parts (e.g. oscillating mirrors), a linear array system has a higher reliability and longer life expectancy
NON-PHOTOGRAPHIC SYSTEMS
• The Landsat Concept (emerged in late 1960s) – Launch a dedicated, unmanned land-observing satellite to
collect, archive and distribute remotely sensed data to users in agriculture, forestry, environmental science, geology, land cover/use, water resources, and marine science.
• History
– Landsat-1 launched in July, 1972
– Landsats 1 - 3 carried RBV and MSS sensor
– Landsat-4, launched 1982, carried new Thematic Mapper (TM) sensor, Landsat 5 also carries TM.
– Landsat 5 recently decommissioned (November 2012)
– Landsat 6 launch failed
– Landsat-7, with Enhanced TM sensor, launched April 1999, but developed a line scan anomaly problem that compromised the data and made it unusable for most users
– Landsat 8 Operational Land Imager (OLI) launched February 2013
LANDSAT PROGRAM (USA)
TM scene: bands 4,5,3
color composite
(Sioux Falls, SD)
• 8 bit data (0-255 DNs)
• data strips “framed” into a
185x185 km scene
• 30m ground resolution per
pixel with non-thermal
detectors
(120m for thermal band 6)
Wavelength (mm)
0.4 0.5 0.6 0.7 0.8 2.0 0.9 1.5 2.5
7 1 2 3 4 5
TM Bands:
Landsat 8 OLI bands are similar to Landsat
TM except two visible blue bands so band 1
TM is band 2 OLI, TM 3 is OLI 4, etc.
LANDSAT TM: sensor applications
TM BandWavelengthRange (mm)
Spectral Region Applications
1 0.45-0.52 Bluewater penetration, coastal mapping,soil/veg. discrimination, culturalfeature ID
2 0.42-0.60 GreenChlorophyll reflection band (peakgreen reflectance of veg.), veg. IDand vigor, cultural feature ID
3 0.63-0.69 RedChlorophyll absorption band(Vegetation discrimination),cultural feature ID
4 0.76-0.90 Near IRVeg. types, plant stress, biomasscontent, soil mositurediscrimination, water delineation
5 1.55-1.75 Mid-IRSoil and veg. moisture content,clouds vs. snow
6 10.4-12.5 Thermal IRVegetation stress, soil mositurediscrimination, thermal mapping
7 2.08- 2.35 Mid-IRVeg. moisture content, rock andmineral discrimination
OLI band
2
3
4
5
6
7
Landsat 8
Operational Land Imager (OLI)
Landsat Data
Continuity
Mission
(LDCM)
Bands Wavelength
(micrometers)
Resolution
(meters)
Band 1 - Coastal aerosol 0.43 - 0.45 30
Band 2 - Blue 0.45 - 0.51 30
Band 3 - Green 0.53 - 0.59 30
Band 4 - Red 0.64 - 0.67 30
Band 5 - Near Infrared (NIR) 0.85 - 0.88 30
Band 6 - SWIR 1 1.57 - 1.65 30
Band 7 - SWIR 2 2.11 - 2.29 30
Band 8 - Panchromatic 0.50 - 0.68 15
Band 9 - Cirrus 1.36 - 1.38 30
Band 10 - Thermal Infrared (TIRS)
1 10.60 - 11.19 100
Band 11 - Thermal Infrared (TIRS)
2 11.50 - 12.51 100 Worldwide Reference System-2 (WRS-2) path/row system
Sun-synchronous orbit at an altitude of 705 km (438 mi) 233 orbit cycle; covers the entire globe every 16 days (except for the highest polar latitudes) Inclined 98.2° (slightly retrograde) Circles the Earth every 98.9 minutes Equatorial crossing time: 10:00 a.m. +/- 15 minutes
LANDSAT TM data acquisition for Maine
• Worldwide Reference
System (WRS)- 8 scenes
• Imagery archived and
catalogued by USGS EROS
Data Center (Sioux Falls)
• Glovis Search archive on
web for available imagery
• Search parameters:
– WRS Path / Row
– date
– maximum cloud cover
– browse images
• Systeme Pour l’Observation de la Terre (SPOT)
– French Space Agency, along-track (pushbroom) scanner – SPOT-1, SPOT-2 and -3 (launched 1986, 90 and 93,
respectively): 3 spectral bands (20m ground resolution) + Panchromatic band (10m)
– SPOT-4 (1998), adds 20m Middle Infrared (MI) or Short Wave Infrared (SWIR) band
– SPOT-5 (2002), 10 m multispectral (3 bands), 20m MI or short wave, 5m panchromatic (2 sensors capable of 2.5 m panchromatic)
– Two identical High Resolution Visible (HRV) imaging systems (using CCD detector arrays): 1 Panchromatic, 1 multispectral
– pointable optics enable nadir and off-nadir scanning for greater repeat coverage and stereo viewing
– used in forestry, agriculture, ecological, land cover/use, and topographic mapping applications
SPOT Sensor System (French)
sun-synchronous orbit
altitude: 822 km
orbital period: 101 minutes (14+
orbits/day)
repeat coverage (nadir): 26 days
however off-nadir:approx. 5 days
swath: 60km at nadir, 80km on
west and east off-nadir
SPOT PROGRAM orbital and sensor characteristics
High Resolution Visual (HRV) sensor
• Advanced Very High Resolution Radiometer (AVHRR) sensor
– National Atmospheric and Oceanic Administration meteorological satellites (7 in series)
– now with 5 spectral bands: 1 visible, 1 near-IR, 3 thermal-IR
– applications: weather and climate; water surface temperature measurement; snow cover mapping; flood monitoring; global vegetation mapping and changes; regional soil moisture, fire, storm, and volcanic monitoring; mapping regional drainage and physiographic features
NOAA SATELLITES (USA)
AVHRR orbital characteristics
• Altitude: 833km
• 2400 km swath width
• 1.1 km ground resolution at nadir
• twice daily coverage
• Daylight and nighttime orbits
SENSOR COMPARISONS spectral resolution (#bands and location)
4
Thermal
Reflected
Mid_infrared
Orbit: 705 km, 10:30 a.m. descending node (Terra) or
1:30 p.m. ascending node (Aqua), sun
synchronous, near-polar, circular
Swath
Dimension
2330 km (cross track) by 10 km (along track at
nadir)
Launch
Dates
TERRA_MODIS December 1999
AQUA_ MODIS May 2002
Spatial
Resolution
250 m (bands 1-2)
500 m (bands 3-7)
1000 m (bands 8-36)
MODIS (USA)
Orbit, swath width and sensor resolution
Multi-resolution (250, 500, 1000m) and hyperspectral at 1000m resolution
MODIS (250m,500m) and Landsat TM and Reflected Bands Comparison
Band/Sensor MODIS Landsat
Red 0.620-0.670µm 0.63-0.69µm
NIR 0.841-0.876µm 0.76-0.90 µm
Blue 0.459-0.479µm 0.45-0.52 µm
Green 0.545-0.565 µm 0.52-0.60 µm
Middle-IR 1.230-1.250µm
Middle-IR 1.628-1.652µm 1.55-1.75µm
Middle-IR 2.105-2.155µm 2.08-2.35µm
Resolution 250m, 500m 30 m
Swath width 2330 km 185 km
Temporal Daily 16 days
Price Free $600/sceneFree as of
2009
Landsat 8 OLI
0.64-0.69
0.85-0.88
0.45-0.51
0.53-0.59
1.57-1.65
2.11-2.29
SENSOR COMPARISONS area covered by one scene
SENSOR COMPARISONS and Data Costs
Cost Update (4/2009)
MSS –free if available
TM/ETM+/OLI(30m) = Free
(ETM+ includes 15m Pan)
SPOT-4(MS or Pan)= $1900?
SPOT-5(10m or 5m)= $3375?
AVHRR/MODIS are
Free- Internet download
Old! Costs
Ecosystem Sensor System Spatial Extent Grain Size Plant ID Level
Biome,
continent
AVHRR,
MODIS 1000m
Hundreds of
thousands sq.
km.
1 km – 500m General land
cover (Level 1)
Regional,
country
MODIS 250m,
Landsat TM
and OLI
Thousands of
sq. km.
500- 30m General land
cover
(level 1-2)
State,
ecoregion,
watersheds
Landsat, TM
and OLI,
SPOT, others,
SAR
Hundreds of sq.
km.
30 – 10 m Forest type
(level 2-3)
Local
landscape ,
forest stands
Spot, IKONOS,
LIDAR, Digital
Cameras,
Aircraft
Hyperspectral
Tens to low
hundreds of sq.
km.
10 – 1m Forest
type/species
group and
detailed land
cover (Level 3-
4)
Forest plot Highest
resolution
sensors, ground
< ten sq. km. to
one-ten ha or
less
1m – 1 ft Tree or canopy
measurement,
some single
species ID
SENSOR COMPARISONS
• Landsat MSS – archival, historical (no longer collected), oldest earth
resource satellite at medium spatial resolution (1972) • Landsat TM, ETM+& Landsat 8 OLI
– improved multispectral resolution (7 bands (more for OLI). – Older TM historical archive than SPOT – Has visible blue & thermal band (SPOT does not) – larger area coverage and less cost (free) /area (than SPOT)
• SPOT HRV – Improved geometric quality (along track scanner, but
Landsat 8 OLI now has along track scanning) – off-nadir viewing (stereo possible) and more frequent revisit
than Landsat – Better spatial (5m -Pan and 10m Multispectral) than Landsat
• NOAA AVHRR and MODIS – Huge area covered, twice daily repeat coverage, better
temporal resolution than Landsat or SPOT – MODIS at 1000m has highest spectral resolution (36 bands) – regional applications and global vegetation monitoring – May be too coarse for many applications but free data