REMOTE SENSING OF NATURAL RESOURCES

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Satellite Imaging
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Remote Sensing Basics

• Many new satellite systems, and continue to
  develop new systems.
• Range in applications from
• - Global Positioning Systems
• - Satellite Radio
• - Atmospheric Conditions
• - Oceanography
• - Land Use

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Remote Sensing Basics

• Types of Remote Sensing
• Active (RADAR) Energy supplied from the source
• Passive Energy supplied from the sun.
• Imaging A raster image is developed. Important
  when spatial relationships are critical.
• Non-Imaging Gathers information without
  locating the object. When spectral information
  is more important than spatial.

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Issues of Resolution

• Can be applied to any type of remote sensing.
• Resolution includes
• Spatial Spectral
• Temporal Radiometric

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Remote Sensing Basics

• Light Energy
• Portions of the spectrum are grouped together and
  referred to as bands

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Remote Sensing Basics

• Spectral resolution refers to the number of
  individual bands used.
• High spectral resolution - Data in many discrete
  wavelengths are collected. These systems are
  referred to as HYPERSPECTRAL.

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Remote Sensing Basics
Low spectral resolution - Bands are designed to
collect data over a wider span of wavelengths.
These systems are often referred to as
MULTISPECTRAL.
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Remote Sensing Basics

• Spectral resolution is important because
• - Reflectance in certain wavelengths may tell
  you something about the object.
• So, you must understand a little bit about light
  physics and a little bit about the objects you
  are trying to find in an image when planning a
  satellite acquisition.

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Remote Sensing Basics

• Measured energy is a function of
• Atmospheric effects
• Object characteristics
• Sun angle
• Wavelength
• Surface geometry

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Remote Sensing Basics

• Sun angle
• Because light is scattered as it approaches or
  leaves the earths surface
• The farther away we are from the sun, the
  greater the amount of scatter, then
• The weaker the correlation between spectral
  signature and the object of interest.
• The distance between the earth and the sun is
  referred to as Path Length.
• This is why most satellite acquisitions occur
  between 10 am and 2 pm.

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Remote Sensing Basics

• Wavelength
• Shorter wavelengths have a greater tendency to
  scatter.
• Example Sunsets are orange and red
• As the sun sets, the path length between the sun
  and the surface increases.
• There is a greater tendency for light to scatter.

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Remote Sensing Basics

• Nearly all the blue and green light is
  scattered away by the time it reaches the earth.
• Leaving behind orange and red.

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Remote Sensing Basics

• Surface Geometry

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Spatial Resolution
(Holle 1997, Stennis Space Center)
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Radiometric Resolution

• This means for each band a digital value will
  be assigned.
• The digital value is dependent upon the amount of
  energy reaching the center and the radiometric
  resolution of the sensor.
• An 8-bit system can assign a DV of 0-255.
• A perfect reflector will receive a DV of 255.

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Radiometric Resolution
(Holle 1997, Stennis Space Center)
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Temporal Resolution

• How often do you require data?
• Yearly
• Monthly
• By Season

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Class Presentations