Remote Sensing II Sensors Konari, Iran Image taken 2/2/2000 The Mand River and the small town of Konari nestle in the Zagros Mountains in western Iran.

Major Satellite Systems High spatial resolution Quickbird, IKONOS, OrbView-3, SPOT-5 PAN, IRS-P6 Medium spatial resolution Landsat-5 TM, Landsat-7 ETM+, ASTER, SPOT Low spatial resolution MODIS, ENVISAT, GOES, AVHRR, MSS

Sensor types Pushbroom (along track) vs. Whiskbroom (across track) SPOT and IKONOS: Pushbroom Landsat: Whiskbroom Pushbroom scanners generally have higher radiometric resolution because they have longer “dwell time” than across-track scanners, which move laterally across landscape as they also move forward

Orbits Most of these satellites are in sun-synchronous orbit The satellite passes over the same part of the Earth at roughly the same local time each day Its “inclination” is about 8 degrees off of polar orbit The fact that the earth is not a perfect sphere makes the orbital plane rotate slowly around the earth (this would not happen if it were perfectly polar)

Orbits Slow motion of orbital plane matches the latitudinal motion of the sun in the sky over the year Maintains similar sun angles along its ground trace for all orbits That means that a given location always gets the same mean sunlight angle, which provides consistent lighting

LANDSAT First started by NASA in 1972; later turned over to NOAA Since 1984 satellite operation and data handling are managed by a commercial company EOSAT LANDSAT-7 launched in 1999; developed scan line error in 2003 Only 5 is still working; outdated

Thematic Mapper spectral resolution LANDSAT Several sensor types Multi-spectral scanner (MSS) – LANDSAT-1 through LANDSAT-5 Thematic Mapper (TM) – LANDSAT-4 and -5 Enhanced Thematic Mapper (ETM+) – LANDSAT-7 Thematic Mapper spectral resolution

LANDSAT ETM+ Slightly different bands than TM; otherwise similar, stressing continuity Check out the movie

LANDSAT TM Applications Band Nominal Spectral location Applications 1 Blue Water body penetration, soil-water discrimination, forest type mapping, cultural feature ID 2 Green Green reflectance peak of veg, for veg ID and assessment of vigor, cultural feature ID 3 Red Chlorophyll absorption region, plant species differentiation, cultural feature ID 4 Near infrared Veg types, vigor and biomass content, delineating water bodies, soil moisture assessment 5 mid infrared (1.55-1.75 mm) Veg moisture, soil moisture, diff of soil from clouds 6 Thermal infrared Veg stress analysis, soil moisture, thermal mapping 7 mid infrared(2.08-2.35 mm) Discriminating mineral and rock types, veg moisture

LANDSAT 16 day repeat cycle Orbit takes about 99 minutes (14.5 per day) Follows earth’s rotation so crosses the equator at the same time (~10 a.m.) 183 km swath width; 170 km data frame 233 orbits per 16 days

LANDSAT Extensive archive distributed by the Earth Resource Observation System (EROS) Data Center of the US Geological Survey Available at http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/ETM

LANDSAT

SPOT Satellite Pour l'Observation de la Terre operated by the French Space Agency, Centre National d'Etudes Spatiales (CNES). 5 satellites launched 1986-2002 (several are still operational) Each has 2 High Resolution Visible (HRV) sensors constructed with multilinear array detectors, or “Pushbroom scanners” that record multispectral data along a wide swath

SPOT The position of each HRV unit can be changed by ground control to observe a region of interest that is at an oblique angle to the satellite—up to ±27º relative to the vertical. Off-nadir viewing allows for acquisition of stereoscopic imagery (because of the parallax created) and provides a shorter revisit interval of 1 to 3 days. Any point on 95% of the Earth can be imaged any day by one of the satellites

SPOT Two modes: panchromatic and multispectral

SPOT

IKONOS Developed by Space Imaging, launched 1999 Has sun-synchronous orbit and crosses equator at 10:30 AM Highly maneuverable: can point at a new target and stabilize itself in seconds, enabling it to follow meandering features The entire spacecraft moves, not just the sensors, allowing data collection at angles of up to 45°from nadir (allows for side-by-side and fore-aft stereo imaging) Employs a linear array scanner (“pushbroom”) 11 km swath width; customizable

IKONOS 1m multispectral image of Dubai

Worldview-2 DigitalGlobe satellite launched in October, 2009 Very agile, and has increased on-board storage High altitude (770 km), sun synchronous orbit Short revisit time 8 spectral bands 16.4 km swath width

Worldview-2 1m multispectral image of Dubai

Panchromatic Film Source VT Orthophotos Sensor Film Spatial Resolution Spectral Coverage Radiometric Resolution 8-bit 1

Color Film Source Duchess County Orthophotos Sensor Film Spatial Resolution 0.62ft Spectral Coverage Radiometric Resolution 8-bit 1 1 1

CIR Digital Source Emerge Orthophotos Sensor Digital Camera Spatial Resolution 0.6m Spectral Coverage Radiometric Resolution 8-bit 1 1 1

Oblique Imagery 64ft 38ft Imagery © Pictometery, 2007

Tsang Po River, Tibet – 1m Panchromatic IKONOS-2 www.spaceimaging.com Spatial Resolution Pan: 1m MS: 4m Spectral Coverage Radiometric Resolution 11-bit Temporal Resolution 3-4 days Scene Size 13 x 13km 1 1 1 1 1 Source: Space Imaging Tsang Po River, Tibet – 1m Panchromatic

Woodstock, VT– 1m Panchromatic Waitsfield, VT– 4m Multispectral IKONOS-2 © Space Imaging © Space Imaging Woodstock, VT– 1m Panchromatic Waitsfield, VT– 4m Multispectral

Manhattan, NY – 0.61m Multispectral Quickbird-2 www.digitalglobe.com Spatial Resolution Pan: 61cm - 72cm MS: 2.44m – 2.88m Spectral Coverage Radiometric Resolution 11-bit Temporal Resolution 3-4 days Scene Size 32 x 32km 1 1 1 1 1 Source: DigitalGlobe Manhattan, NY – 0.61m Multispectral

Mauritius – 2.44m Multispectral Boston, MA – 0.61m Panchromatic Quickbird-2 Source: DigitalGlobe Mauritius – 2.44m Multispectral Source: DigitalGlobe Boston, MA – 0.61m Panchromatic

Deepwater Horizon clean up– 0.5m Multispectral Worldview-2 Spatial Resolution Pan: 50cm MS: 1.8m – 2.4m Spectral Coverage Radiometric Resolution 11-bit Temporal Resolution 1.1-3.7 days Scene Size 16 x 16km 1 1 1 1 1 1 1 1 Source: DigitalGlobe Deepwater Horizon clean up– 0.5m Multispectral

Worldview-2 Boulder, CO – 0.5m Multispectral Source: DigitalGlobe Source: DigitalGlobe Boulder, CO – 0.5m Multispectral Deepwater Horizon – 0.5m Multispectral

Brattleboro, VT – 30m Multispectral Landsat-7 Spatial Resolution Pan: 15m MS: 30m/60m Spectral Coverage Radiometric Resolution 8-bit Temporal Resolution 16 days Scene Size 185 x 185km 1 1 1 1 1 2 1 Brattleboro, VT – 30m Multispectral

Landsat-7 Harriman Reservoir, VT – 30m Multispectral St. Albans Bay, VT – 30m Multispectral

ASTER Spatial Resolution MS: 15m/30m/90m Spectral Coverage Radiometric Resolution 8-bit/12-bit Temporal Resolution Varies Scene Size 60x 60km 1 1 1 6 5 Boston, MA – 90m Thermal

ASTER Winooski River, VT – 15m Multispectral Otter Creek, VT – 15m Multispectral