Transcript Remote Sensing

Remote Sensing
Hyperspectral Imaging
AUTO3160 – Optics
Staffan Järn
Introduction
• Measurement of object properties on the earth’s surface
using data acuired from aircraft and satellites
• Passive remote sensing
– Natural radiation that is emitted or reflected by the object or
surrounding areas
– Reflected sunlight is the most common radiation measured
• Active remote sensing
– Emits energy
– Detects and measures the radiation that is reflected or
backscattered from the target.
– RADAR and LiDAR systems measures time delay to establish the
location, height, speed and direction of an object.
History
• 1858 - Photographs of Paris from balloon
• 1972 - Landsat Multispectral Scanner System (MSS)
satellite.
– High resolution earth images with 4 spectral bands. Each about
100 nm wide.
– 80 m pixel size. 185 x 185 km
• Today
– Hundreds of images of the same area in 10nm spectral bands
– Spectrum from 400 to 2400 nm
• Advanced Visible/InfraredRed Imaging Spectrometer (AVIRIS),
airborne
• HyMap, airborne
• Hyperion, satellite
Applications
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Environmental monitoring (urban growth, hazardous waste)
Global change (global warming, deforestation)
Agriculture (crop condition, yield prediction)
Nonrenewable natural resources (wetlands, soils, forests,
oceans)
Meteorology (atmosphere dynamics, weather prediction)
Mapping (topography, land use, civil engineering)
Military surveillance (strategic policy, tactical assessment)
News media (illustrations, analysis)
Multispectral & Hyperspectral Imaging
• Both are related
• Difference in number of
bands
• Depending on what is
appropriate to the purpose
• Multispectral
– Discrete and narrow bands
– Spectrum from visible to
longwave infrared
• Hyperspectral
– Imaging narrow spectral
bands over a continuous
spectral range, and produce
the spectra of all pixels in the
scene
Hyperspectral Imaging
• Collect image data in
multiple narrow
spectral bands
• Possible to derive a
continuous spectrum
for each image cell
Hyperspectral Imaging
• In reflected-light spectroscopy the property wanted to obtain
is called Spectral Reflectance.
– The ratio of reflected energy as a function of wavelength
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Reflectance varies with wavelength for most materials
because energy at certain wavelengths is scattered or
absorbed to different degrees.
Absorption bands
Result
• Image cube for spatial-spectra data
Table of Remote Sensing systems
Sources
• Remote Sensing, Models and Methods for Image
Processing – R.A. Schowengerdt
• Introduction to Hyperspectral Imaging, pdf
document from AUTO3090 Chemometrics course
• Wikipedia – Remote Sensing http://en.wikipedia.org/wiki/Remote_sensing
• Wikipedia - Hyperspectral Imaging http://en.wikipedia.org/wiki/Hyperspectral_imag
ing