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Remote sensing presentation explanation pptx
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- 2. • Remote sensingis the acquiring of information from a distance. • NASA observes Earth and other planetary bodies via remote sensors on satellites and aircraft that detect and record reflected or emitted energy. • Orbits • Observing with the Electromagnetic Spectrum • Sensors • Resolution • Data Processing, Interpretation, and • Analysis
- 3. Orbits • Satellites canbe placed in several types of orbits around Earth. • Low-Earth orbit (approximately 160 to 2,000 km above Earth), • Medium-Earth orbit (approximately 2,000 to 35,500 km above Earth), and • High-Earth orbit (above 35,500 km above Earth). • Satellites orbiting at 35,786 km are at an altitude at which their orbital speed matches the planet's rotation, and are in what is called geosynchronous orbit (GSO). • In addition, a satellite in GSO directly over the equator will have a geostationary orbit. • A geostationary orbit enables a satellite to maintain its position directly over the same place on Earth’s surface. • Sun-synchronous; the satellite passes over the same location at the same solar time each cycle, e.g. NASA’s Aqua satellite
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- 5. Observing with theElectromagnetic Spectrum • Visible light sits in the middle of that range of long to shortwave radiation. • human eye is able to detect a small portion. • Instrumentation is needed to detect all other forms
- 6. • The primarysource of the energy observed by satellites, is the Sun. • Snow has a very high albedo and reflects up to 90% of incoming solar radiation. • The ocean, on the other hand, reflects only about 6%.
- 7. Sensors • Sensors thatuse natural energy from the Sun are called passive sensors. • Those that provide their own source of energy are called active sensors.
- 8. Resolution • Radiometric resolutionis the amount of information in each pixel, that is, the number of bits representing the energy recorded.
- 9. • Spatial resolutionis defined by the size of each pixel within a digital image and the area on Earth’s surface represented by that pixel.
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- 11. • Spectral resolutionis the ability of a sensor to discern finer wavelengths, or • the ability of a sensor to define fine wavelength intervals. or • The range of wavelengths that a single band in an imaging system can detect.
- 12. • Temporal resolutionis the time it takes for a satellite to complete an orbit and revisit the same observation area. • This resolution depends on the orbit, the sensor’s characteristics, and the swath width. • Because geostationary satellites match the rate at which Earth is rotating, the temporal resolution is much finer. • Polar orbiting satellites have a temporal resolution that can vary from 1 day to 16 days.
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- 14. Interpretation of imagery Lookfor a Scale • One of the first things people want to do when they look at a satellite image is identify the places that are familiar to them:
- 15. • Look forpatterns, shapes, and textures
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- 18. • Water • Plants •Bare ground • Cities • Atmosphere • Ground truthing