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17 August 2000 Dr. Charles Randell P.Eng

EO Satellite Primer. TransCanada Transmission & Colonial Pipeline Company. 17 August 2000 Dr. Charles Randell P.Eng. 2 Main Categories of Satellites. Geostationary satellites: - stationary above a fixed point on the equator - “footprint” does not change

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17 August 2000 Dr. Charles Randell P.Eng

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  1. EO Satellite Primer TransCanada Transmission & Colonial Pipeline Company 17 August 2000 Dr. Charles Randell P.Eng

  2. 2 Main Categories of Satellites Geostationary satellites: - stationary above a fixed point on the equator - “footprint” does not change - orbits very high (1000s of km) above earth - typically communications and weather satellites GOES Image 36000 km orbit 1 - 4 km resolution

  3. 2 Main Categories of Satellites Polar (near polar) orbiting satellites: - lower orbits (100s of km) - orbit follows a pattern that takes it near the poles - “footprint” moving continuously in periodic pattern. Repeats every 25-35 days. - “earth observation” (EO) satellites Celebrating 25 Years of Achievement

  4. Satellite Specifications Spacecraft parameter: orbit period serviceable life Sensor parameters type of sensor temporal resolution (tied to orbit) spatial resolution radiometric resolution spectral resolution

  5. Temporal resolution: Revisit time, or how often you can “see” the same area on earth Many sensor have overlapping swaths so it is possible to see the same spot on earth every 1 - 5 days. Seeing the same spot from the same perspective, or point in space depends on repeat period of the spacecraft. This is important for certain subtle change analyses. Use more than one satellite to increase revisit frequency

  6. Spatial resolution: Minimum spacing between two points for which they can be individually distinguished. Generally accepted “working definition”: area on the ground covered by each pixel

  7. 30 28 27 28 36 40 42 31 28 27 40 36 44 42 31 40 38 17 10 1 Satellite imagery is digital: Numerically it is a matrix where each matrix element contains a number corresponding to the image picture element - pixel The number may be real or complex For optical images, the number represents intensity of the pixel For radar images, the number represents a magnitude and phase

  8. Spatial resolution: Image with 25 m resolution

  9. Spatial resolution: Image with 5 m resolution

  10. Image with 1 m resolution

  11. red + green + blue = 8 bit multispectral image Spectral resolution

  12. Reduced radiometric resolution - 3 bit image

  13. Panchromatic (grayscale) image

  14. Currently 2 Types of Imaging Sensors on Satellites 1. Synthetic Aperture Radar (SAR) 2. Optical - panchromatic - multispectral

  15. SAR Satellites • SAR is an active radar • Penetrates cloud & fog • penetrates darkness • very reliable coverage • RADARSAT Fine Beam Image • (this clip 9 km × 11 km)

  16. SAR Satellites • Radar not optical image • prone to noise • interpretation not • “intuitive” • “complex” data permits • very power techniques • for information extraction

  17. Oil slick in false colored SAR Image

  18. RADARSAT Receiving Stations

  19. SAR Satellites SAR Satellite Mission Date Frequency Resolution ( GHz) (m) Seasat 1978 June – October 1.3 L-band 25 SIR-A 1981 November 1.3 L-band 40 SIR-B 1984 October 1.3 L-band 17–58 Almaz-1 1991 March – 1993 3.0 S-band 15–30 JERS-1 1992 February – 1998 1.3 L-band 18 ERS-1 1991 July – 1996 (1999) 5.3 C-band 20–30 SIR-C/X-SAR 1994 April 1.3 L-band 25–200 5.3 C-band 9.6 X-band SRTM 2000 February 5.3 C-band 30 9.6 X-band ERS-2 1995 April – 5.3 C-band 20–30 RADARSAT-1 1995 November – 5.3 C-band 8–100 ENVISAT 2001 June 5.3 C-band 30–150 2001 Q1 J-band 10–100 PALSAR RADARSAT-2 2002 5.3 C-band 3–100 TerraSAR 2004 L/X-band 1

  20. Optical Satellites IKONOS 4m multispectral image • Optical equipped satellites • are passive imaging systems. • Effectively cameras in space. • Interpretation more intuitive • Subject to usual visibility limitations • Multiple spectral bands permit detection/classification of numerous phenomena • Subject to “usual” visibility limitations • Interpretation more intuitve • Multiple bands permit reliable detection of numerous phenomena

  21. Hyperspectral image of oil from underground pipeline serving Chaulk Point Generating Station, MD. Ruptured April 7, 2000 Multispectral and hyperspectral imagery good for detecting color and anomalous regions such as stressed vegetation, moisture changes, temperature change, and local atmospheric anomolies

  22. Optical Satellites • Optical satellites have recently • passed a milestone in commercial • capability • “Taskable” satellites • with 1 meter resolution • Multiple bands permit reliable detection of numerous phenomena IKONOS 1m panchromatic image Sawmill & lumber yard

  23. Encroachment and Gas DetectionOptical Satellites (1m / 4m resolution) Satellite Revisit Data Launch Time Delivery Date IKONOS-2 2 days 1+ days operational EROS-A1 2-3 days - Q4 ‘00 (1st of 8) Orbview-3 < 3 days - Jan '01 Quickbird 1-5 days - 2001

  24. Summary: • Two types of EO satellites: SAR & optical • Highest resolutions range from 1 m to 30 m • Data can be available within hours • EO satellites where traditionally for scientific and government use • Current and future satellite missions designed with commercial/industrial applications in mind

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