Chapter 6 - Aerial + Satellite Images Flashcards
This is the acquisition of surface data from remote distance
Remote sensing
What are two ways images are collected for remote sensing?
Aircraft and satellites
Remote sensing images serve as the basis for these
Maps
What are the two types of data that remote sensing images provide?
Spatial and attribute data
In what year was the first photo taken by balloon?
1858
In what decade were the first wartime aerial photos taken?
1910s
In what decade were the first aerial photography programs?
1940s
In what decade were the first satellites for espionage, weather, and communications?
1960s
In what decade was the first digital imagery for earth mapping?
1970s
In what decade did free web images become available?
2000s
What are the two main types of remote sensing?
Passive and active
This type of remote sensing used electromagnetic energy from the sun
Passive
Passive remote sensing images capture this from the Earth’s surface
Reflected wavelengths
What two types of photos are included in passive remote sensing?
Aerial photos and satellite images
Is passive remote sensing affected by night or clouds?
Yes
In this type of remote sensing, an aerial platform directs an energy beam at the Earth’s surface
Active
In active remote sensing, energy reflected from the Earth’s surface is captured via these
Scanners
What are the two types of active remote sensing?
Radar and lidar
This type of active remote sensing uses radio waves
Radar
This type of active remote sensing uses laser light
Lidar
Is active remote sensing affected by night or clouds?
No
What are four benefits of remote sensing imagery?
- Large area coverage; 2. Extended spectral range; 3. Geometric accuracy; 4. Historical value
What are at least four of six uses for remote sensing imagery?
- Navigation/mapping; 2. Forest inventory; 3. Geologic surveys; 4. Natural hazards; 5. Land use change; 6. Wildlife habitat assessment
This describes the full range of radiation wavelengths
Electromagnetic spectrum
Remote sensing principally detects these two regions of EM wavelengths
Visible light and near infrared
What are three things that can happen to electromagnetic energy?
It can be reflected, absorbed, or transmitted
What can happen with absorbed electromagnetic energy?
It can be emitted
Do different substances absorb and reflect different wavelengths of electromagnetic energy?
Yes
This affects incoming electromagnetic energy from the sun/space
Atmosphere
What are two atmospheric components that affect electromagnetic energy?
Clouds/gasses/dust and water vapor
This atmospheric component reflects and absorbs energy
Clouds/gasses/dust
This atmospheric component absorbs energy and reduces transmittance
Water vapor
Visible light consists of these three colors/wavelengths
Red, yellow, blue
These describe reflectance of surface features to different wavelengths
Spectral reflectance curves
This describes photographs taken by aircraft
Aerial photography
Aerial photographs were first taken from these in the 1850s
Balloons
Aerial photography developed rapidly after the invention of this
Airplane
This is the measurement of photos
Photogrammetry
This is the identification of surface features from aerial photographs
Photo interpretation
What are at least three of four uses of aerial photos in GIS?
- Source of accurate coordinates; 2. Provide spatial location of features; 3. Provide surface attribute data; 4. Serve as background layers in GIS
What are two types of cameras used in aerial photography?
Film and digital cameras
This type of camera used in aerial photography produces an image directed onto film emulsion
Film camera
What are two types of film cameras used in aerial photography?
Small format and large format
What are two sizes of small format cameras used in aerial photography?
35mm and 70mm
Which is more expensive, small format or large format film cameras?
Small format
Which produces higher quality images for aerial photography, small or large format film cameras?
Small format
What is the size of large format film cameras in aerial photography?
240mm
Large format film cameras are used on aircraft designed for this
Precise flight
What are small format aerial photography film camera images used for?
Qualitative surveys
Do large format film cameras for aerial photography have low distortion?
Yes
What are large format aerial photography film cameras used for?
Geometric mapping
These are replacing film cameras for aerial images
Digital cameras
Digital cameras use this to detect different wavelengths
Scanning element
How is data from digital cameras recorded?
In long continuous strips
Digital cameras eliminate the need for this
Scanning film into digital format
Large format cameras print these onto photos
Fiducial marks
What are three types of film used in aerial photography?
Panochromatic, color, infrared
This type of film is sensitive to a range of visible light and is commonly used for many purposes
Panochromatic
This type of film is inexpensive and provides good resolution
Panochromatic
This type of film depicts imagery in natural color and is the most common choice for map projects
Color
This type of film detects variation in infrared wavelengths
Infrared
This type of film is high contrast and small differences in reflectivity show up as sharp color differences
Infrared
This type of film is good for vegetation analysis, but must be taken “leaves-on”
Infrared
What are the two types of infrared film?
Black and white and false-color
Aerial films usually include this that records flight and camera info
Data strip
These are used to produce 3D images of surfaces
Stereo photos
Adjacent overlapping images are called this
Stereopairs
Stereo photos are used to draw these
Elevation contour lines
Stereo photos can be used to remove this from photos
Relief distortion
Overlap in this creates stereo photos in aerial photography
Flight path
Onboard computers aid in these for aerial photography
Precise flight patterns
Raw aerial photos contain these
Distortions
What are at least three of four types of aerial photograph distortions?
- Relief displacement; 2. Camera tilt; 3. Camera/film/lens errors; 4. Atmosphere
Raw photos have this view, as they are not orthographic
Perspective view
This creates distortion caused by terrain and buildings
Relief displacement
In photos distorted by relief displacement, tall objects appear to lean outward and radiate from this
Principal point
How does displacement change with distance from a principal point in relief displacement distortion?
Displacement rises
These objects have more displacement in relief displacement distortion
Taller objects
What are two aspects of a photo that relief displacement affects?
Angles and distances
This is not constant in photos distorted by relief displacement
Photo scale
Distortion-corrected aerial images have this view
Orthographic view
This is in line with the camera’s optical axis in an aerial photograph
Principal point
Where are points above the datum displaced?
Outward
Where are points below the datum displaced?
Inward
This type of distortion occurs when the optical axis is not vertical and causes apparent convergence of distant objects
Camera tilt
Photo contracts specify how much tilt?
< 3 degrees
These help reduce camera tilt
Camera stabilizers
Camera tilt data are recorded on this
Data strip
This the effect of terrain and tilt on geometric accuracy
Tilt convergence error
Does tilt convergence error increase or decrease with decreasing map scale?
Increase
Flaws in these can cause displacement
Lenses
This camera part can distort the focal plane
Camera platten
What can happen to film to produce errors?
Shrinking/swelling
Are camera/film/lens errors smaller on large format cameras?
Yes
This source of photo distortions is important for high altitude images
Atmosphere
This process corrects errors of tilt and relief displacement
Photo rectification
What are two things required by the photo rectification process?
Stereopairs and special equipment
Photo rectification produces this, a photo that is geometrically accurate and has uniform scale
Orthophoto
This machine was initially used to produce orthophotos
Orthophotoscope
These are now used to produce orthophotos
Modern photogrammetric workstations
Satellite scanners contain these to image the Earth’s surface
Detector arrays
Satellite detectors convert electromagnetic radiation into this
Recorded signal
In satellite imagery, a detector array is directed toward Earth and a scanner does this
Sweeps surface
Imaging satellites occupy this type of orbit to ensure the field of view is always at the same time of day
Sun-synchronous
Do satellite imaging scanners have a broader electromagnetic range than aerial cameras?
Yes
Why do satellites have a broader range than aerial cameras and produce less relief distortion?
High perspective results in optical axis near vertical
Satellite image data requires this, at higher costs than aerial photography
Special processing
What are at least three of four lower resolution satellite imagery systems?
- Landsat; 2. Moderate Resolution Image Sensor; 3. Vegetation; 4. SPOT
This is the longest running remote sensing system, with over 30 years of continuous coverage
Landsat
In what year did Landsat begin as a NASA system?
1972
In what year did Landsat switch from a NASA system to NOAA system?
1979
How many Landsat satellites have there been?
7
How many Landsat satellites are currently operating?
2
What is Landsat’s return time for mid-latitudes?
17 days
What are the two Landsat satellites?
Multispectral scanner and thematic mapper
This was the first satellite land scanner
Landsat’s multispectral scanner
How many bands does Landsat’s multispectral scanner have?
5
What is the resolution of Landsat’s multispectral scanner?
80 m
What two types of electromagnetic radiation does Landsat’s multispectral scanner detect?
Visible and near infrared
How many bands does Landsat’s thematic mapper have?
7
What three types of electromagnetic radiation does Landsat’s thematic mapper detect?
Visible, near-infrared, mid-infrared
What is the resolution of Landsat’s thematic mapper?
30 m
What resolution scanner does the newest Landsat thematic mapper add?
15 m panochromatic
Satellite images are catalogued using these
Scene index maps
This satellite imaging system is a NASA system with a wide range of electromagnetic radiation, from visible to thermal
Moderate Resolution Image Sensor (MODIS)
What is the resolution range of MODIS?
250-1000 m
What is the return time for MODIS at 1000 m resolution?
2 days
This imaging satellite was developed by the French government
Vegetation
What two wavelength bands does the Vegetation satellite collect?
Visible and infrared
What is the resolution of the Vegetation satellite?
1150 m
How many kilometers does the Vegetation satellite cover?
2400 km
This imaging satellite was developed by the French government and started in 1986
SPOT
What two types of images are taken by SPOT’s scanners?
Panochromatic and multispectral
What is the panochromatic resolution of SPOT’s scanners?
2.5-10 m
What is the image extant of SPOT?
60 x 60 km
Can SPOT take stereophotographs?
Yes
What resolution is required for a satellite imagery system to be considered high resolution?
<1 m
High resolution satellite systems can record these two types of data
Panochromatic and multispectral
What are three reasons why high resolution satellite systems are replacing aerial photos for many needs?
- Resolution is now close to aerial imagery; 2. Wider electromagnetic range/extent; 3. Easier distortion correction
Are all high resolution satellite imagery systems commercial?
Yes
What are four examples of high resolution satellite systems?
IKONOS, QuickBird, Worldview, GeoEye
What are two types of active remote sensing?
RADAR and LIDAR
In this type of active remote sensing, satellites send radio waves to the Earth’s surface and record reflection
RADAR
RADAR is carried on these
Airplanes
These two regions have RADAR satellites in operation
US and Europe
What two types of mapping is RADAR used for?
Topography and cover type mapping
This obtained full global elevation data in 2000
Shuttle Radar Topography Mission
In this type of active remote sensing, satellites direct a laser light to the Earth’s surface and record reflection
LIDAR
What is the resolution of LIDAR?
10 cm
What are commercial LIDAR systems used for?
Elevation data
What two applications are LIDAR systems being tested for?
Vegetation typing and water quality
Most LIDAR are carried on these, though satellite systems are in development
Aircraft
Which form of remote sensing traditionally had higher resolution: aerial imaging or satellite imaging?
Aerial imaging
Which form of remote sensing can provide electromagnetic data not available to the other?
Satellite imaging
Which form of remote sensing has the advantage of using digital data?
Satellite imaging
These are eliminating the digital advantage of satellite imaging
Digital aerial cameras
Do remote sensing images often require interpretation?
Yes
This is the science of identifying objects in images
Photo interpretation
Photo interpretation often requires this
Ground truthing
What are at least five of eight types of photo elements that aid in identification?
- Tone brightness/color; 2. Relative size; 3. General object shape/outline; 4. Texture; 5. Spatial arrangement patterns; 6. Light/shadows; 7. Geographic location patterns; 8. Association of neighboring objects
