ENR 3700 Final Exam Study Guide
Non imaging systems - ANSWER acquire the intensity/strength of signals over the field
of view of the sensors, generally not visualized as spatially - continuous images (Ex.
sonar, lidar)
imaging systems - ANSWER acquire a digital image of the field of view, with some
information about how the strength of signal varies in space continuously
active sensors - ANSWER transmit man made electromagnetic energy and then record
the amount of radiation that returns/ reflects to the sensor system (e.g. lidar, radar, and
sonar)
passive sensors - ANSWER record naturally occurring energy (electromagnetic
radiation) that is reflected or emitted from the terrain of interest (e.g. optical, thermal)
polar orbits - ANSWER an orbit that passes above or nearly above both poles of the
planet on each revolution
it allows for lower altitudes and more image resolution
take multiple passes of the earth before returning to the same location
almost all earth mapping satellites use polar or near polar orbits
geostationary orbits - ANSWER give the best temporal resolution
are able to view earth from above
as they move in synchronicity with earths rotation, they can provide regular coverage
for a region and help in forecasting
Why are orbits important factors for determining temporal resolution? - ANSWER
satellite orbits/attitude directly determine temporal resolution
they are able to view the earth from above
environmental remote sensing - ANSWER the practice of deriving information about the
earths land and water surfaces using images acquired from an overhead perspective,
using electromagnetic radiation in one or more regions of the electromagnetic
spectrum, reflected or emitted from the earths surface
why is the atmosphere noise rather than signal to us? - ANSWER
the three dimensions of an image - ANSWER x, y, & z
the spectral signature for each pixel is simple a Z profile of digital numbers
, hyperspectral - ANSWER spectral dimensions or spectral bands:
>100 bands
offers fine characterization of reflectance spectra
multispectral - ANSWER < 15 bands
space is covered with cells
each cell has one number indicating the amount of energy received from the cell
the cell is called pixel (picture element)
the size of the pixel is the spatial resolution
each band will generate a layer of remotely sensed data, usually with the same cell
(pixel) size
for landsat satellite, we will have 6 layers of data corresponding to the 6 bands
landsat spatial resolution - ANSWER 30m
digital number - ANSWER each pixel has a geographic coordinate and
reflectance/intensity value, or digital number (DN)
pixels are spatial footprints captured by sensors: circular in nature, but always
displayed on-screen as squares
radiometric correction (DN - reflectance or DN - temperature) - ANSWER is needed to
convert DN to meaningful physical quantities such as reflectance and temperature
The RGB color model - ANSWER visualize digital numbers: RGB color model for image
display
image to red channel, image to green channel, image to blue channel
the color at each channel is represented by a number from 0 to 255
the RGB color model is an additive color model in which red, green, and blue light are
added together in various ways to reproduce a broad array of colors
Why does the RGB model work for human eyes? - ANSWER Eyes photoreceptors (rods
and cones) which respond to particular wavelengths of light to give animals/humans
their sense of sight
Di chromatic - dogs
Tri - chromatic - human
False color composite - ANSWER false color (b4 (nir) R, b3 (red) G, b2(green) B)
Non imaging systems - ANSWER acquire the intensity/strength of signals over the field
of view of the sensors, generally not visualized as spatially - continuous images (Ex.
sonar, lidar)
imaging systems - ANSWER acquire a digital image of the field of view, with some
information about how the strength of signal varies in space continuously
active sensors - ANSWER transmit man made electromagnetic energy and then record
the amount of radiation that returns/ reflects to the sensor system (e.g. lidar, radar, and
sonar)
passive sensors - ANSWER record naturally occurring energy (electromagnetic
radiation) that is reflected or emitted from the terrain of interest (e.g. optical, thermal)
polar orbits - ANSWER an orbit that passes above or nearly above both poles of the
planet on each revolution
it allows for lower altitudes and more image resolution
take multiple passes of the earth before returning to the same location
almost all earth mapping satellites use polar or near polar orbits
geostationary orbits - ANSWER give the best temporal resolution
are able to view earth from above
as they move in synchronicity with earths rotation, they can provide regular coverage
for a region and help in forecasting
Why are orbits important factors for determining temporal resolution? - ANSWER
satellite orbits/attitude directly determine temporal resolution
they are able to view the earth from above
environmental remote sensing - ANSWER the practice of deriving information about the
earths land and water surfaces using images acquired from an overhead perspective,
using electromagnetic radiation in one or more regions of the electromagnetic
spectrum, reflected or emitted from the earths surface
why is the atmosphere noise rather than signal to us? - ANSWER
the three dimensions of an image - ANSWER x, y, & z
the spectral signature for each pixel is simple a Z profile of digital numbers
, hyperspectral - ANSWER spectral dimensions or spectral bands:
>100 bands
offers fine characterization of reflectance spectra
multispectral - ANSWER < 15 bands
space is covered with cells
each cell has one number indicating the amount of energy received from the cell
the cell is called pixel (picture element)
the size of the pixel is the spatial resolution
each band will generate a layer of remotely sensed data, usually with the same cell
(pixel) size
for landsat satellite, we will have 6 layers of data corresponding to the 6 bands
landsat spatial resolution - ANSWER 30m
digital number - ANSWER each pixel has a geographic coordinate and
reflectance/intensity value, or digital number (DN)
pixels are spatial footprints captured by sensors: circular in nature, but always
displayed on-screen as squares
radiometric correction (DN - reflectance or DN - temperature) - ANSWER is needed to
convert DN to meaningful physical quantities such as reflectance and temperature
The RGB color model - ANSWER visualize digital numbers: RGB color model for image
display
image to red channel, image to green channel, image to blue channel
the color at each channel is represented by a number from 0 to 255
the RGB color model is an additive color model in which red, green, and blue light are
added together in various ways to reproduce a broad array of colors
Why does the RGB model work for human eyes? - ANSWER Eyes photoreceptors (rods
and cones) which respond to particular wavelengths of light to give animals/humans
their sense of sight
Di chromatic - dogs
Tri - chromatic - human
False color composite - ANSWER false color (b4 (nir) R, b3 (red) G, b2(green) B)
