chapter 3 sensors and platforms part 2 p2 Flashcards
Passive microwave systems are based on a ………………….. that detects wavelengths in the ……………… region of the spectrum
type of radiometer
microwave
Passive microwave systems are based on a type of radiometer that detects wavelengths in the microwave region of the spectrum. Because of the nature of microwave radiation
optical systems cannot be used for the detection of this range of wavelengths
Passive microwave systems are based on a type of radiometer that detects wavelengths in the microwave region of the spectrum. Because of the nature of microwave radiation, optical systems cannot be used for the detection of this range of wavelengths. As with optical systems though, both …………………… systems are available
nonimaging and imaging
The components of a microwave radiometer are
an antenna, receiver, and recording device
Microwave energy emitted from Earth’s surface is collected by
an antenna
Microwave energy emitted from Earth’s surface is collected by an antenna, converted by…………………… into a ……………………
a receiver into a signal
Microwave energy emitted from Earth’s surface is collected by an antenna, converted by a receiver into a signal, and
recorded.
The features of electromagnetic energy measured by microwave radiometers are
polarity, wavelength, and intensity
The features of electromagnetic energy measured by microwave radiometers are polarity, wavelength, and intensity. These properties provide useful information about
the structure and composition of an object
Most of the applications of passive microwave radiometers have been in
the fields of atmospheric and oceanographic research
Most of the applications of passive microwave radiometers have been in the fields of atmospheric and oceanographic research. It has also proven to be an effective tool for the measurement of
soil moisture, an important parameter in studying vegetation
By combining a number of detectors or radiometers into ………………….., it is possible to create a sensor that
detector arrays
can acquire a 2D image of an area
There are three basic designs for imaging sensors
frame, pushbroom, and mechanical scanner.
The first two designs are
similar.
The frame sensor is a 2D array of detectors that acquires an entire image in
one exposure
The first two designs are similar. The frame sensor is a ………… array of detectors that acquires an entire image in one exposure similar to the way
2D
a camera captures an image on film
A pushbroom sensor is a ……….. . array that obtains
1D
an image one line at a time
A pushbroom sensor is a 1D array that obtains an image one line at a time. Each new data line is added as the platform
moves forward
Each new data line is added as the platform moves forward, building up
an image over time
. A pushbroom sensor is a 1D array that obtains an image one line at a time. Each new data line is added as the platform moves forward, building up an image over time. In a mechanical scanner system the sensor acquires
only one or several pixels in any given instant
In a mechanical scanner system the sensor acquires only one or several pixels in any given instant, but since the scanner
physically sweeps or rotates the sensor (a radiometer) or a mirror back and forth, an image is produced.
This category of sensor (………………………)
passive visible, infrared and thermal imaging systems
This category of sensor (passive visible, infrared and thermal imaging systems) contains ………………………..that have been deployed on
numerous instruments
a wide variety of platforms
This category of sensor (passive visible, infrared and thermal imaging systems) contains numerous instruments that have been deployed on a wide variety of platforms and used for
many applications
Most modern imaging systems are
multispectral (acquiring data for more than one limited spectral area)
The recording of each discrete spectral sampling is referred to as
an image band or channel.
Using image processing techniques, multiple (usually …………) bands selected from a
three
multispectral image database
Using image processing techniques, multiple (usually three) bands selected from a multispectral image database can be combined to make
a single color composite image
Active systems supply their own illumination energy which can be
controlled
Some advantages active systems have over passive sensors are they
do not require solar illumination of surfaces or perfect weather conditions to collect useful data
Some advantages active systems have over passive sensors are they do not require solar illumination of surfaces or perfect weather conditions to collect useful data. Consequently they can be deployed……………………. depending on
at night or in conditions of haze, clouds, or light rain (depending on the wavelength of the system).
