Geog 190 Exam Flashcards
1
Q
Objects also _____ that has been emitted by other objects.
A
Reflect radiation
2
Q
All objects emit __? Except objects at __?
A
Electromagnetic Radiation, Absolute Zero
3
Q
The most familiar form of Electromagnetic Radiation
A
Visible Light
4
Q
Generated by several mechanisms, including changes in the energy levels of electrons, acceleration of electrical charges, decay of radioactive substances, and the thermal motion of atoms and molecules
A
Electromagnetic (EM) energy
5
Q
As this radiation approaches the Earth, it passes through the atmosphere before reaching the Earth’s surface. What happens to it?
A
Some is reflected upward from the Earth’s surface, some is absorbed at the surface of the Earth and is then reradiated as thermal energy.
6
Q
____ Radiation, such as that generated by imaging radars, is also used for remote sensing
A
Man-Made Radiation
7
Q
Electromagnetic Radiation consists of ____ which varies in magnitude in a direction perpendicular to the direction of propagation, and ____ which is oriented at right angles to the electrical field and is propagated in phase with the electrical field.
A
Electrical field (E), Magnetic field (H)
8
Q
The distance from one wave crest to the next
A
Wavelength
9
Q
Measured as the number of crests passing a fixed point in a given period of time.
A
Frequency
10
Q
Equivalent to the height of each peak. Often measured as energy levels (formally known as spectral irradiance), expressed as watts per square meter per micrometer (i.e., as energy level per wavelength interval).
A
Amplitude
11
Q
Specifies the extent to which the peaks of one waveform align with those of another. Measured in angular units, such as degrees or radians.
A
Phase (of a waveform)
12
Q
If two waves are aligned, they oscillate together and are said to be ____? (a phase shift of 0 degrees).
A
In Phase
13
Q
If a pair of waves are aligned such that the crests match with the troughs, they are said to be ____?
A
Out of Phase
14
Q
Which spectrum, from 0.30 to 15 µm, defines those wavelengths that can be reflected and refracted with lenses and mirrors.
A
Optical Spectrum
15
Q
Which spectrum extends from about 0.38 to 3.0 µm; it defines that portion of the solar spectrum used directly for remote sensing.
A
Reflective Spectrum
16
Q
Radiation of significance for remote sensing can be said to begin with the ____ region, a zone of short-wavelength radiation that lies between the X-ray region and the limit of human vision. Means “beyond the violet”. Since it’s easily scattered by the Earth’s atmosphere, it is not generally used for remote sensing of Earth materials.
A
Ultraviolet / Ultraviolet Radiation
17
Q
The ____ of an object is defined by the color of the light that it reflects
A
Color
18
Q
Limits of the ____are defined by the sensitivity of the human visual system
A
Visible Spectrum
19
Q
Primary Colors (Answer based on wavelength): 0.4 to 0.5 µm, 0.5 to 0.6 µm, 0.6 to 0.7 µm
A
Blue, Green, Red
20
Q
Equal proportions of the three additive primaries combine to form what?
A
White / White light
21
Q
Each of the three subtractive primaries absorbs a third of the visible spectrum (Color Absence). Yellow absorbs ____, Cyan absorbs ____, and Magenta absorbs ____?
A
Blue, Red, Green
22
Q
A mixture of equal proportions of pigments of the three subtractive primaries yields ___?
A
Black
23
Q
Wavelengths longer than the red portion of the visible spectrum are designated as the ___? It extends from 0.72 to 15 µm—making it more than ____ times as wide as the visible light spectrum.
A
Infrared / Infrared Region, 40
24
Q
Defined as those regions of the infrared spectrum closest to the visible. Can use films, filters, and cameras with designs similar to those intended for use with visible light. Essentially solar radiation reflected from the Earth’s surface
A
Near Infrared and Mid Infrared radiation
25
Consisting of wavelengths well beyond the visible, extending into regions that border the microwave region, emitted by the Earth. Consists of “heat,” or “thermal energy”.
Far Infrared / Far Infrared Region
26
In this region, the longest wavelengths commonly used in remote sensing are those from about 1 mm to 1 µm in wavelength. The shortest wavelengths in this range have much in common with the thermal energy of the far infrared. The longer wavelengths of this region merge into the radio wavelengths used for commercial broadcasts.
Microwave / Microwave Region
27
Planck discovered that electromagnetic energy is absorbed and emitted in discrete units called ____? The size of each unit is directly proportional to the ____ of the energy’s radiation.
Quanta or Photons, Frequency
28
The generation of electric currents by the exposure of certain substances to light, as the effect of the impact of these discrete units of energy (quanta) on surfaces of certain metals, causing the emission of electrons.
Photoelectric Effect
29
Made the wave model of electromagnetic radiation.
James Clerk Maxwell
30
Based on the assumption from classical (mechanical) physics that light and other forms of electromagnetic energy propagate as a series of waves. Best explains some aspects of the observed behavior of electromagnetic energy (e.g., refraction by lenses and prisms and diffraction), whereas quantum theory provides explanations of other phenomena (notably, the photoelectric effect).
Wave Model
31
The rate at which photons (quanta) strike a surface. Measured in Watts (W)
Radiant Flux (Fe)
32
____ measures radiation that strikes a surface, _____ defines the rate at which radiation is emitted from a unit area (also measured in watts per square meter)
Irradiance, Radiant Exitance
33
All objects with temperatures above absolute zero have _____ and ____ energy.
Temperature, Emit
34
The amount of energy and the wavelengths at which it is emitted depend on the ____ of the object.
Temperature
35
As the temperature of an object increases, the total amount of energy emitted also _____, and the wavelength of maximum (peak) emission becomes ______.
Increases, Shorter
36
A _____ is a hypothetical source of energy that behaves in an idealized manner. It absorbs all incident radiation; none is reflected. Emits energy with perfect efficiency. A hypothetical entity because in nature all objects reflect at least a small proportion of the radiation that strikes them and thus do not act as perfect reradiators of absorbed energy.
Blackbody
37
_____ states that the ratio of emitted radiation to absorbed radiation flux is the same for all blackbodies at the same temperature.
Kirchhoff’s Law
38
The emissivity of a true blackbody is __, and that of a perfect reflector (a whitebody) would be ___.
1, 0
39
_____ is a useful measure of their effectiveness as radiators of electromagnetic energy. Those objects that tend to absorb high proportions of incident radiation and then to reradiate this energy will have high ones and vice versa.
Emissivity
40
Defines the relationship between the total emitted radiation (W) (often expressed in watts · cm–2) and temperature (T) (absolute temperature, K).
Stefan–Boltzmann Law
41
S-B law states that ___ blackbodies emit more energy per unit area than do ___ blackbodies.
Hot, Cool
42
Specifies the relationship between the wavelength of radiation emitted and the temperature of a blackbody.
Wien’s Displacement Law
43
According to Wien's Displacement Law, as blackbodies become ____, the wavelength of maximum emittance shifts to _____ wavelengths.
Hotter, Shorter
44
__ passing through the atmosphere undergoes modification through scattering, absorption, and refraction.
Solar Energy
45
The redirection of electromagnetic energy by particles suspended in the atmosphere or by large molecules of atmospheric gases
Scattering
46
The effect of scattering is to redirect ____ so that a portion of the incoming solar beam is directed back toward space, as well as toward the Earth’s surface.
Radiation
47
Occurs when atmospheric particles have diameters that are very small relative to the wavelength of the radiation. It is also ______, meaning that the amount of scattering changes greatly as one examines different regions of the spectrum. Also sometimes referred to as _____
Rayleigh Scattering, Wavelength Dependent, Clear Atmosphere Scattering
48
At sunset, only the _____ wavelengths pass through, hence the sky being color orange or red.
Longer
49
Involves larger atmospheric particles like dust, pollen, smoke, and water droplets.
Those particles that cause this scattering have diameters that are roughly equivalent to the wavelength of the scattered radiation. It is also _______, but it tends to be greatest in the lower atmosphere (0 to 5 km), where larger particles are abundant.
Mie Scattering, Wavelength Dependent
50
Caused by particles that are much larger than the wavelength of the scattered radiation. For radiation in and near the visible spectrum, such particles might be larger water droplets or large particles of airborne dust. It is ________, meaning that it is not wavelength dependent hence we observe it as a whitish or grayish haze because all visible wavelengths are scattered ____.
Nonselective Scattering, Nonselective, Equally
51
Atmosphere has its own ____ due to scattering.
Brightness
52
Alters colors and brightness of objects in landscapes based on distance from the observer called ______
Atmospheric Perspective
53
Scattering affects remote sensing by excluding ______ wavelengths because it is greatly affected by scattering (Short-Wave Radiations)
Blue and Ultraviolet
54
Scattering makes dark objects appear brighter and bright objects appear darker, reducing _____.
Contrast
55
Bending of light rays at the contact area between two media that transmit light.
Refraction
56
Defined as the ratio between the velocity of light (c) in a vacuum and its velocity in the medium (cn). Assuming uniform media, light passing into a denser medium is deflected toward the surface normal.
Index of Refraction (n)
57
Defines the angle that the refracted ray follows as it passes from one medium to another.
Snell's Law
58
_____ of radiation occurs when the atmosphere hinders/prevents transmission of radiation or its energy through the atmosphere.
Absorption
59
______ is formed by the interaction of high-energy ultraviolet radiation with oxygen molecules (O2) high in the atmosphere. Absorption of UV (mainly less than 0.24 μm) prevents transmission of this radiation to the lower atmosphere.
Ozone
60
______ absorbs in the mid and far infrared regions. Also occurs in low concentrations (about 0.03% by volume of a dry atmosphere), mainly in the lower atmosphere. Its strongest absorption occurs in the region from about (13 to 17.5 μm) in the mid infrared.
Carbon Dioxide
61
____ is several times more effective in absorbing radiation than the other two gases combined. Commonly present in the lower atmosphere (below about 100 km) in amounts that vary from 0 to about 3% by volume.
Water Vapor
62
Atmosphere is not completely transparent due to gases because these gases together form important barriers to transmission of electromagnetic radiation through the atmosphere. The atmosphere selectively transmits energy of certain wavelengths and those wavelengths that are relatively easily transmitted through the atmosphere are referred to as _____.
Atmospheric Windows
63
Atmospheric Windows defines the wavelengths that can be used for forming ____.
Images
64
______ occurs within atmospheric processes.
Remote Sensing
65
Sun emits maximum intensity at approximately ____ µm
0.5
66
_______, with wavelengths longer than 10 μm, represents sensible heat or thermal radiation. Earth's atmosphere absorbs much of the radiation emitted by Earth
Only wavelengths passing through atmospheric windows can be used for remote sensing
Terrestrial Radiation
67
Heating of the lower atmosphere by the ground surface, which causes upward movement of air, then movement of cooler air to replace the original air.
Turbulent Transfer
68
Occurs when a ray of light is redirected as it strikes a nontransparent surface.
It depends on surface nature (roughness or smoothness), wavelength, and angle of illumination
Reflection
69
______ reflection for smooth surfaces.
Redirects all, or almost all, of the incident radiation in a single direction.
Specular Reflection
70
For specular surfaces, the angle of incidence is _____ to the angle of reflection
Equal
71
_______ reflection for rough surfaces
Also known as _______.
Energy is scattered more or less equally in all directions.
Diffuse Reflection, Isotropic Reflector
72
Lambert's cosine law and inverse square law govern _________
Reflection Brightness
73
Reflection characteristics of a surface are described by the ______, a mathematical description of the optical behavior of a surface with respect to angles of illumination and observation, given that it has been illuminated with a parallel beam of light at a specified azimuth and elevation.
Bidirectional Reflectance
Distribution Function (BRDF)
74
_______ occurs when radiation passes through a substance without significant attenuation. Measured as transmitted radiation over incident radiation
Transmission
75
Occurs when an object illuminated with radiation of one wavelength emits radiation at a different wavelength.
It can reveal differences between healthy and stressed leaves through contrasting surfaces
Fluorescence
76
Denotes the orientation of oscillations within the electric field of electromagnetic energy. _____ sunglasses reduce glare by absorbing horizontally polarized bright radiation.
Polarization, Polarizing
77
Within the atmosphere, polarization of light is related to the nature and ________ of atmospheric aerosols and atmospheric clarity.
Abundance
78
_______ is the relative brightness of a surface expressed as a ratio of observed brightness to irradiance. As a ratio, it is a dimensionless number (between 0 and 1). It is commonly expressed as a percentage and is crucial in remote sensing applications.
Reflectance
79
In the instance of emitted (far infrared) radiation, the ______is the immediate source of radiation. For reflected radiation, _____ may be the source.
Object itself, The sun
80
______ patterns help identify features based on unique spectral characteristics.
Using cameras and other remote sensing instruments, we can observe the brightnesses of objects over a range of wavelengths, so that there are numerous points of comparison between brightnesses of separate objects.
Spectral Response
81
A set of such observations or measurements constitutes a spectral response pattern, sometimes called the ________ of an object.
Spectral Signature
82
Remote sensing strategies
recording the reflection of solar radiation from Earth's surface, record radiation emitted from the Earth's surface
83
Belonging to a third class of remote sensing instruments generate their own energy, then record the reflection of that energy from the Earth’s surface.
Sensors
84
These sensors generate their own energy, transmit energy toward Earth's surface and record reflected energy.
Best represented by imaging radars and lidars
Active Remote Sensing
85
Instruments sense energy emitted by the Earth, reveals information about thermal properties of materials, patterns of moisture, vegetation, surface materials, and man-made structures
Passive Remote Sensing
86
Sources of Emitted Radiation: Give like 2 idk
Emitted radiation from Earth's surface such as Geothermal energy, heat from steam pipes, power plants, buildings, and forest fires
87
Systems for acquiring _____? rely on the basic components common to the familiar handheld cameras we all have used for everyday photography. These systems include:
Aerial Images,
1. Lens
2. Light-sensitive surface
3. Shutter
4. Camera body
88
System; to gather light to form an image
Lens
89
System; To record the image
Light-sensitive surface
90
System; Controls entry of light
Shutter
91
System; A light-tight enclosure that holds the other components together in their correct positions
Camera Body
92
Aerial Cameras (Analog) include these components in a structure that differs from that encountered in our everyday experience with cameras:
Film Magazine
Drive Mechanism
Lens Cone
93
Whereas other cameras may have been designed to acquire images (for example) of very large areas or under unfavorable operational conditions, the design of the ______? is optimized to acquire high-quality imagery of high positional fidelity; it is the ______? that forms the current standard for aerial photography.
Metric Camera
94
A ______? design differs from an analog camera because the image is captured by digital technology, _____? do not require the film and the complex mechanisms for manipulating the film.
Digital Camera
95
The _____? gathers reflected light and focuses it on the focal plane to form an image. In its simplest form, a _____? is a glass disk carefully ground into a shape with nonparallel curved surfaces
Lens
96
The change in optical densities as light rays pass from the atmosphere to the lens and back to the atmosphere causes _____? of light rays
Refraction
97
Optical characteristics of lenses are determined largely by the _________? and the ______?
Refractive index of the glass, The degree of curvature
98
Imperfections in lens shape contribute to _______?, a source of error that distorts images and causes loss of image clarity.
Spherical Aberration
99
Most aerial cameras use ________?, formed from many separate lenses of varied sizes, shapes, and optical properties.
Compound Lenses
100
The ______? joins the centers of curvature of the two sides of the lens.
Optical Axis
101
Although refraction occurs throughout a lens, a plane passing through the center of the lens, known as the ________?, is considered to be the _______? within the lens cameras.
Image Principal Plane, Center of Refraction
102
The image principal plane intersects the optical axis at the ________?
Nodal Point
103
Parallel light rays reflected from an object at a great distance (at an “infinite” distance) pass through the lens and are brought to focus at the principal _____? — the point at which the lens forms an image of the distant object.
Focal Point
104
The ______? passes through the nodal point without changing direction; the paths of all other rays are deflected by the lens.
Chief Ray
105
A plane passing through the focal point parallel to the image principal plane is known as the _______?
Focal Plane
106
In a simple positive lens, the ______? is defined as the distance from the center of the lens to the focal point, usually measured in inches or millimeters.
Focal Length
107
For a given lens, the focal length is not identical for all wavelengths.
E.g. blue light brought to a focal point with a shorter distance than red light.
This effect is the source of ______?
Chromatic Aberration
108
The field of view of a lens can be controlled by a ____?, a mask positioned just in front of the focal plane.
Field Stop
109
An _______? is usually positioned near the center of a compound lens; it consists of a mask with a circular opening of adjustable diameter.
Aperture Stop
110
_____? is measured as the diameter of the adjustable opening that admits light to the camera.
Aperture Size
111
A ______? f number means that the aperture opening is small relative to focal length; a _____? f number means that the opening is large relative to focal length.
Large, Small
112
Why use f numbers rather than direct measurements of aperture?
One reason is that standardization of aperture with respect to focal length permits _________? using a value that is independent of camera size.
Specification of Aperture Size
113
Lenses for aerial cameras typically have rather ____?. As a result, light reaching the focal plane from the edges of the field of view is typically dimmer than light reflected from objects positioned near the center of the field of view. This effect creates a dark rim around the center of the aerial photograph—an effect known as _____?
Wide FOV, Vignetting
114
It is possible to employ an ________?, darker at the center and clearer at the periphery, that can be partially effective in evening brightnesses across the photograph.
Antivignetting Filter
115
The _____? controls the length of time that the film is exposed to light. The simplest shutters are often metal blades positioned between elements of the lens, forming _______? or “between-the-lens,” shutters.
Shutter, Intralens
116
An alternative form of shutter is the ______?, consisting of a metal or fabric curtain positioned just in front of the detector array, near the focal plane.
Focal Plane Shutter
117
The ______? shutter subjects the entire focal plane to illumination simultaneously and presents a clearly defined perspective that permits use of the image as the basis for precise measurements.
Intralens/Between-the-lens
118
High-quality aerial cameras usually include a capability known as _________? (or forward motion compensation) to acquire high-quality images.
Image Motion Compensation
119
_______? can be classified according to the orientation of the camera in relation to the ground at the time of exposure
Aerial Photographs
120
________? have been acquired by cameras oriented toward the side of the aircraft
Oblique Aerial Photographs
121
________? show the horizon; _________? are acquired with the camera aimed more directly toward the ground surface and do not show the horizon.
High Oblique Aerial Photographs, Low Oblique Aerial Photographs
122
______? are acquired by a camera aimed directly at the ground surface from above
Vertical Photographs
123
The science of making accurate measurements from aerial photographs (or from any photograph) is known as __________?
Photogrammetry
124
Analog aerial cameras are manufactured to include _________? attached rigidly to the camera so that the positions of the index marks are recorded on the photograph during exposure.
Adjustable Index Marks
125
These ________? (usually four or eight in number) appear as silhouettes at the edges and/or corners of the photograph
Fiducial Marks
126
Lines that connect opposite pairs of fiducial marks intersect to identify the __________?, defined as the intersection of the optical axis with the focal plane, which forms the optical center of the image.
Principal Point
127
The _________? is defined as the point on the ground vertically beneath the center of the camera lens at the time the photograph was taken
Ground Nadir
128
The ____________? is defined by the intersection with the photograph of the vertical line that intersects the ground nadir and the center of the lens (i.e., the image of the ground nadir).
Photographic Nadir
129
Accurate evaluation of these features depends on systematic and regular _______? of aerial cameras—the camera’s internal optics and positioning of fiducial marks are assessed and adjusted to ensure the optical and positional accuracy of imagery for photogrammetric applications. ________? can be achieved by using the cameras to photograph a standardized target designed to evaluate the quality of the imagery, as well as by internal measurements of the camera’s internal geometry
Calibration
130
The _____? can be defined informally as the focus of tilt.
Imagine a truly vertical photograph that was taken at the same instant as the real, almost vertical, image. The almost vertical image would intersect with the (hypothetical) perfect image along a line that would form a “hinge”; the _________? is a point on this hinge.
Isocenter
131
_______? are errors caused by an inferior camera lens, camera malfunction, or similar problems.
These distortions are probably of minor significance in most modern photography flown by professional aerial survey firms.
Optical Distortions
132
______? is caused by displacement of the focal plane from a truly horizontal position by aircraft motion (Figure 3.8). The focus of tilt, the _______?, is located at or near the principal point.
Tilt, Isocenter
133
Because of routine use of high-quality cameras and careful inspection of photography to monitor image quality, today the most important source of positional error in vertical aerial photography is probably ____________?
Relief Displacement
134
__________? can form the basis of measurements of heights of objects, but its greatest significance is its role as a source of positional error.
Relief Displacement
135
_______? is acquired using a family of instruments that can systematically view portions of the Earth’s surface, recording photons reflected or emitted from individual patches of ground, known as ________? (“picture elements”), that together compose the array of discrete brightnesses that form an ______?
Digital Imagery, Pixels, Image
136
_________? are light-sensitive substances that generate minute electrical currents when they intercept photons from the lens, thereby creating an image from the matrix of brightnesses that is proportional to the strengths of the electrical charges that reach the focal plane.
Detectors
137
Digital Cameras have 2 alternative designs of Detectors:
Charged-coupled devices (CCDs)
Complementary metal oxide semiconductor (CMOS) chips.
138
A _____? is formed from light-sensitive material embedded in a silicon chip.
The ______? receives photons from the scene through an optical system designed to collect, filter, and focus radiation.
CCD, Potential Well
139
These elements can be combined using microcircuits to form _____?
Detectors arranged in a single line form a _____?
Detectors arranged in multiple rows and columns form _____?
Arrays, Linear Arrays, 2D Arrays
140
At a specified interval, charges accumulated at each detector pass through a ______?, which controls the flow of data from the detectors.
Transfer Gate
141
Microcircuits connect detectors within an array to form ____?
These permit charges received at each detector to be passed to adjacent elements (in a manner analogous to a bucket brigade), temporarily recording the information until it is convenient to transfer it to another portion of the instrument.
Shift Registers
142
Whereas _____? expose all pixels at the same instant, then read these values as the next image is acquired, _____?instruments expose a single line at a time, then expose the next line in the image while data for the previous line is transferred.
CCDs, CMOS
143
_____? captured images frame by frame, meaning that each image was acquired as a single image corresponding to the single image projected into the focal plane at the time the shutter closed.
Analog Cameras
144
This photographic frame, acquired at a single instant, forms the fundamental unit for the image—every such image is a frame, a portion of a frame, or a composite of several frames. Such cameras are therefore designated as ________? or ____________? which have formed the standard for analog aerial camera designs.
Framing Cameras or Frame-Array Cameras
145
Another design solution for a digital aerial camera is to employ linear rather than area arrays.
One such design employs a camera with separate lens systems to view:
The nadir
The forward-looking
The aft-looking position.
146
A large-format-frame digital camera.
It uses four high-resolution panchromatic camera heads (focal length 120 mm) in the center and four multispectral camera heads (focal length 25 mm) on the periphery.
The Intergraph Digital Modular Camera (DMC)
147
The _______? employs multiple lens systems and CCDs positioned in the same plane, but with timing of the exposures to offset exposures slightly such that they view the scene from the same perspective center.
Vexcel UltraCamX
148
The _____? (Figure 3.15) views the Earth with several linear arrays, each oriented to collect imagery line by line, separately from forward-viewing, nadir-viewing, and aft-viewing orientations.
Leica ADS 40
149
The usual digital sensors have ____? that encompass the visible spectrum (with a maximum in the green region) and extend into the near infrared. Although arrays used for consumer electronics specifically filter to exclude the near infrared (NIR) radiation, aerial cameras can use this sensitivity to good advantage.
Spectral Sensitivity
150
______? use emulsions that are sensitive over a range of wavelengths, so even if their maximum sensitivity lies in the red, green, or blue regions, they are sensitive to radiation beyond the desired limits.
Color Films
151
In contrast, ______? can be designed to have spectral sensitivities cleanly focused in a narrow range of wavelengths and to provide high precision in measurement of color brightness.
Digital Sensors
152
One alternative strategy uses a single array to acquire data in the three primaries using a specialized filter, known as a ________?, to select the wavelengths that reach each pixel. It is specifically designed to allocate 50% of the pixels in an array to receive the green primary and 25% each to the red and blue primaries
Bayer Filter
153
Peak radiation in the visible region lies in the ___? region.
Green
154
______? is the term that remote sensing practitioners use to refer to the assignment of colors to represent brightnesses in different regions of the spectrum.
Band Combinations
155
_______? means “across the colors,” indicating that the visible spectrum is represented as a single channel (without distinguishing between the three primary colors).
Panchromatic
156
False in the sense that the colors on the image do not match their true colors in nature
False-Color Images
157
_______? region of the spectrum is subject to atmospheric scattering, thereby limiting the utility of natural color images acquired at high altitudes.
Blue
158
Characterized by wavelengths just longer than the longest region of the visible spectrum. Carries important information about vegetation and is not subject to atmospheric scattering
Near-Infrared Region (NIR)
159
Creates a three-band color image by discarding the blue band from the visible spectrum and adding a channel in the NIR
Color-Infrared Region (CIR)
160
Calls for acquisition of vertical aerial photographs by flying a series of parallel flight lines that together build up complete coverage of a specific region.
Flight Plan
161
For framing cameras, each flight line consists of _____?, usually numbered in sequence
Individual Frames
162
The ______? can view the area to be photographed through a viewfinder and can manually trigger the shutter as aircraft motion brings predesignated landmarks into the field of view or can set controls to automatically acquire photographs at intervals tailored to provide the desired coverage
Camera Operator
163
If the plane’s course is deflected by a crosswind, the positions of ground areas shown by successive photographs form the pattern shown known as _____?
Drift
164
_______? is caused by correction of the flight path to compensate for drift without a change in the orientation of the camera.
Crab
165
Usually flight plans call for a certain amount of ________? to duplicate coverage by successive frames in a flight line, usually by about 50–60% of each frame.
Forward Overlap
166
If forward overlap is 50% or more, then the image of the principal point of one photograph is visible on the next photograph in the flight line. These are known as ______?
Conjugate Principal Points
167
When it is necessary to photograph large areas, coverage is built up by means of several parallel strips of photography;
each strip is called a ______?
Flight Line
168
_____? between adjacent flight lines may vary from about 5 to 15%, in an effort to prevent gaps in coverage of adjacent flight lines.
Sidelap
169
However, as pilots collect complete photographic coverage of a region, there may still be gaps (known as _____?) in coverage due to equipment malfunction, navigation errors, or cloud cover.
Holidays
170
Difference in appearances of objects due to change in perspective. If we have two photographs of the same area taken from different perspectives (i.e., from different camera positions), we observe a displacement of images of objects from one image to the other
Stereoscopic Parallax
171
The amount of parallax _______? as objects increase in distance from the observer
Decreases
172
Overlapping aerial photographs record parallax due to the shift in position of the camera as aircraft motion carries the camera forward between successive exposures. If forward overlap is 50% or more, then the entire ground area shown on a given frame can be viewed in _____? using ______?
Stereo, Stereo Triplet
173
Displacement due to stereo parallax is always_____? to the flight line.
Parallel
174
_______? are not planimetric maps because they have geometric errors, most notably the effects of tilts and relief displacement, in the representations of the features they show.
Aerial Photographs
175
Corrected form of an aerial photograph that shows photographic detail without the errors caused by tilt and relief displacement.
Orthophoto
176
Instead of exposing an entire image from a central perspective (i.e., through a single lens), systematically exposes a small section of an image individually in a manner that corrects for the elevation of that small section.
Orthophotoscope
177
Show the fine detail of an aerial photograph without the geometric errors that are normally present and because they can be compiled much more quickly and cheaply than the usual topographic maps.
Orthophotomaps
178
______? are orthophotos prepared in a digital format designed to correspond to the 7.5-minute quadrangles of the U.S. Geological Survey (USGS).
Digital Orthophoto Quadrangles (DOQs)
179
The ________? is based on the use of digital elevation models (DEMs) to represent variations in terrain elevation. The final product is presented (as either panchromatic or CIR imagery) to correspond to the matching USGS 7.5-minute quadrangle, with a supplementary border of imagery representing 50–300 m beyond the limits of the quadrangle, to facilitate matching and mosaicking with adjacent sheets.
Rectification Process
180
A related product, the _______?, formatted to provide a more convenient unit, represents one-fourth of the area of a DOQ at a finer level of detail, is available for some areas.
Digital orthophoto Quarterquadrangle (DOQQ)
181
Science of making accurate measurements from photographs.
Photogrammetry
182
_______? used for analog photogrammetry have traditionally been prepared on glass plates or other dimensionally stable materials (i.e., materials that do not change in size as temperature and humidity change).
Photographs
183
The most frequent application of photogrammetry is the ____? to derive estimates of topographic elevation for topographic mapping.
Analysis of Stereo Aerial Photography
184
Photogrammetrists estimate _______? using ______? for an array of points within a region.
Topographic Relief, Stereo Parallax
185
______?, now the standard for photogrammetric production, offers advantages of speed and accuracy and generates output data that are easily integrated into other production and analytical systems, including GIS..
Soft-copy Photogrammetry
186
Because these systems each collect so many independent views of the same features (due to the use of several lenses, or several linear arrays, as outlined previously), it is possible to apply _______?, which can exploit these redundancies to extract highly detailed positional and elevation data beyond that which was possible using analog photography.
Multi-ray Photogrammetry
187
____? often use prisms and filters to separate light into spectral regions.
Optical Sensors
188
____? are pieces of specialized glass that selectively pass certain wavelengths and block or absorb those that the designer desired to exclude
Filters
189
Most precise (most expensive) filters are manufactured by adding ____? to glass during manufacture. On the other hand,
Less precise, and less durable, filters are manufactured by coating the surface of glass with a ____? that absorbs the desired wavelengths.
Dyes, Film
190
Electronic sensors often use _____?, considered more efficient because of their effectiveness, small size, and light weight than filters. They are closely spaced transmitting slits cut into a flat surface (a transmission grating) or grooves cut into a polished surface (a reflection grating).
Diffraction Gratings
191
Experiences both interference as wavefronts interact with the grating.
_______? causes some wavelengths to be suppressed
______? causes others to be reinforced.
Destructive Interference, Constructive Interference
192
Varies across a specific defined interval because the various filters and diffraction gratings that instruments use to define the spectral limits (i.e., the “colors” that they record) do not define discrete limits,
Spectral Sensitivity
193
The spectral interval measured at the level at which the instrument’s response reaches one-half of its maximum value
Full width, Half maximum (FWHM)
194
Forms a definition of ______?, the narrowest spectral interval that can be resolved by an instrument
Spectral Resolution
195
Specifies the spectral interval used to record brightness in relation to wavelength.
Spectral Sampling Interval / Spectral Bandwidth
