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2023RemoteSensingSensors-Spot-IkonosRevV2.ppt
2023RemoteSensingSensors-Spot-IkonosRevV2.ppt
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slide-01
Introduction to Remote Sensing Types of Remote Sensing Systems (optical) Multispectral remote sensing The collection of reflected, emitted energy from an object or area of interest in multiple bands of the electromagnetic spectrum (Jensen, 2000). Thermal remote sensing Data collection only in the thermal portion of the electromagnetic spectrum (in one or more bands). Hyperspectral remote sensing Data collection in hundreds of very narrow spectral bands.
slide-02
Multispectral remote sensing systems Multispectral remote sensing systems sense the electromagnetic range from 0.3 to 14.0 µm using discrete detectors and scanning mirrors (across track) Landsat MSS, Landsat TM, Landsat ETM+ linear arrays (along track) SPOT HRV, SPOT HRVI, IRS LISS, IKONOS, Quickbird
slide-03
SPOT series satellites Launched by France Stands for Satellite Pour l'Observation de la Terre Operated by the French Space Agency, Centre National d'Etudes Spatiales (CNES) SPOT 1 launched 1986, retired in 1990 SPOT 2 launched 1990, still going SPOT 3 launched 1993 and stopped functioning 1996 SPOT 4 launched in 1998, still going SPOT 5 launched in May 2002 SPOT 6 launched in Sept 2012 SPOT 7 launched in Sept 2014 similar to SPOT 6 https://earth.esa.int/eogateway/missions/spot
slide-04
SPOT image What features can you distinguish by observation? Oxbow Lake Urban Agric.
slide-05
SPOT circular orbits (1-3) SPOT satellites are in sun-synchronous orbit (10:30 am) Its “inclination” is about 8 degrees off of polar orbit Has an altitude of 832 km Revisit rates: 26 days Radiometric resolution is 8-bit Swath width: 60 km under nadir viewing conditions
slide-06
SPOT bands (1-3) Panchromatic band, corresponding to the visible part of the EM spectrum without the blue, from 0.51 to 0.73 µm, yields black and white images. Resolution is 10 m, Pixels per line is 6,000 Good for fine geometrical detail Multispectral bands: • XS1 covering 0.50 to 0.59 µm (green), • XS2 covering 0.61 to 0.68 µ m (red) and • XS3 covering 0.79 to 0.89 µm (near infrared). Spatial resolution is 20 m with multispectral bands. Pixels per line is 3,000.
slide-07
Geographic Coverage of the SPOT HRV and Landsat Thematic Mapper Remote Sensing Systems Jensen, 2000
slide-08
SPOT HRV Each SPOT satellite carries two identical HRV (high- resolution visible) sensors
slide-09
SPOT off-nadir viewing 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. Advantage? Off-nadir viewing allows for: • acquisition of stereoscopic imagery (because of the parallax created) and • provides a shorter revisit interval of 1 to 4 (5) days.
slide-10
SPOT off-nadir viewing Oblique viewing capacity allows it to image any area within a 900 kilometer swath; can be used to increase the viewing frequency for a given point during a given cycle. The frequency varies with latitude: at the equator, a given area can be imaged 7 times during the same 26-day orbital cycle. At latitude 45 degrees, a given area can be imaged 11 times during the orbital cycle, i.e. 157 times yearly and an average of 2.4 days, with an interval ranging from a maximum of 4 days to a minimum of 1 day. Any point on 95% of the earth may be imaged any day by one of the three satellites.
slide-11
SPOT 4 2 identical HR-VIR (high resolution visible and infrared) sensors • addition of a mid-IR band (1.58-1.75 µm), 20 m spatial resolution Vegetation sensor • swath width: 2,250 km • blue band (0.43-0.47 µm), red, near IR, mid IR • 1 km spatial resolution at nadir • global coverage on a daily basis
slide-12
SPOT 5 2 identical HRG (high resolution geometric) sensors • High spatial resolution, 2.5 or 5 m panchromatic band (0.48-0.71 µm) • 10 m with green, red, and near-IR bands • 20 m with mid IR band HRS (high resolution stereoscopic) • facilitate the preparation of DEM at a resolution of 10 m • swath width: 120 km Vegetation sensor • swath width: 2250 km • blue band (0.43-0.47 µm), red, near IR, mid IR • 1 km spatial resolution at nadir • global coverage on a daily basis
slide-13
IKONOS sensor High resolution satellite developed by Space Imaging, launched September 1999. Has sun-synchronous orbit and crosses equator at 10:30 AM Has an altitude of 682 km. Ground track repeats every 11 days. At its nadir it has 11 km swath width. 11 km by 11 km image size
slide-14
IKONOS image Can collect data at angles of up to 45° from vertical both in the along track and across track directions. This allows for: •frequently covering a given area •side by side and fore and aft stereoscopic imaging 1 m IKONOS pan image of Rome Source: spaceimaging.com
slide-15
IKONOS bands IKONOS collects panchromatic band (0.45 to 0.90 um) at 1m resolution Collects four multispectral bands at 4 m resolution •blue (0.45 to 0.52 mm) •green (0.51 to 0.60 mm) •red (0.63 to 0.70 mm) •near IR (0.76 to 0.85 mm) Radiometric resolution is 11 bits, How many values? or 2048 values
slide-16
IKONOS data 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 11 km by 11 km image size, but user specified strips and mosaics can be ordered.
slide-17
2011/7/17 IKONOS Images, Traverse Bay Regions Overview How Large is this Image File? 13,000 MB = 13 GB 19
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Advantages and Disadvantages of High Resolution Imagery • What can be viewed? • Urban/Built-up • Agriculture • Forest • What is the difference between the regular patterns and the other forest plots? Why? 20
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2011/7/17 Old Mission Pt. Orchards, 1 m/4 m Panchromatic Sharpened/Enhanced: What can you see? What can one detect? 21