Photogrammetry Midterm Study Guide
height of camera above the base of the object.
Flying height (H)
The distance from the focal point to the center of a lens
Focal Length
A plane perpendicular to the optical axis passing through the focal point
Focal Plane
Who were balloons invented by?
Joseph-Michel and Jacques-Étienne Montgolfier in 1783 in France.
What term is used to describe the following?: A camera is lifted using a kite and is triggered either remotely or automatically to take aerial photographs.
Kite aerial photography (KAP)
What is the radian flux leaving the surface is constant for any angle of reflectance to the surface?
Lambert surface
What is the End Lap?
Lapping along the flight strip (60%), also known as stereoscopic overlap area.
A simple camera in which an aperture provided by a pinhole in an opaque diaphragm is used in place of a what?
Lens
Causes image positions to be displaced from their ideal locations due to 2 factors.
Lens Distortion
caused by the use of spherical lens elements, resulting in the change of the direction of incoming rays, thus deteriorating the geometric quality.
Lens Distortion
do not degrade image quality but deteriorate the geometric quality (or positional accuracy) of the image.
Lens Distortion
deteriorates the positional accuracy of image points located on the image plane. occurs when light rays passing through the lens are bent, thereby changing directions, and intersecting the image plane at positions deviant from the norm.
Lens distortion
What are classified as either symmetric radial or decentering?
Lens distortions
The Earth's sea surface when the wind, wave, and tidal action ceased, and the oceans were connected through the continents by canals
Mean sea level (geoid)
Major sources of systemic errors remaining in process of reducing photo coordinates to the photo coordinate axis system.
Measurement Errors
consists of making precise measurements from photos and other information sources to determine, in general, the relative locations of points.
Metric photogrammetry
enables finding distances, angles, areas, volumes, elevation, sizes, and shapes of objects.
Metric photogrammetry
What is an electromagnetic wave with a wavelength in the range 0.001-0.3 m, shorter than that of a normal radio wave but longer than those of infrared radiation?
Microwave
What is used in radar, in communications, and for heating in microwave ovens and in various industrial processes?
Microwave
caused by pollen, dust, smoke, water droplets, and other particles in the lower portion of the atmosphere. It occurs when the particles causing the scattering are larger than the wavelengths of radiation in contact with them. responsible for the white appearance of the clouds
Mie scattering
Makes measurements in one photo at a time
Mono-comparator
During what time of the day is most sensor data collected?
Most images are collected within +/- 2 hours of solar noon. In the lecture they mention that this is to prevent extensive shadows in the imagery.
the acquisition of remotely sensed data from more than one time period.
Multi-temporal imaging
a camera with two or more lenses, the axes of the lenses being systematically arranged at a fixed angle in order to cover a widefield by simultaneous exposures in all chambers
Multiple Lens camera
has to do with the use of images from various regions of the EM spectrum (e.g., ultraviolet, visible, infrared, thermal and microwave).
Multispectral
point on Earth directly below the camera. is the point vertically beneath the camera center at the time of exposure.
Nadir
Reverse tone and geometry from original scene.
Negative films
from sea level to the elevation above sea level of an object or a feature.
Object Elevation Above Sea Level(h)
Are exposed with the camera axis intentionally tilted away from the vertical.
Oblique Aerial Photographs
Limitations of Analytical (Numerical) Rectification
Only point features can be rectified, thus the rectified one is not a photo anymore.
Relies on an instrument called rectifier. Uses the photographic process of projection printing.
Optical Mechanical Rectification
What are flat, optically transparent plates that are typically designed to maximize transmission in a specified wavelength range, while minimizing reflection and absorption?
Optical Windows
are often used to protect optical systems and electronic sensors from an outside environment.
Optical Windows
machine designed to fly by the flapping of its wings in imitation of birds.
Ornithopter
An aerial photograph that has been modified so that its scale is uniform throughout.
Orthophoto
The spatial arrangement of certain general forms or relationship. spatial arrangement of objects
Pattern
can be discerned individually
Pattern
the repetitious distribution of single objects in the landscape.
Pattern
Principal point of photo or image
Photo Principal Point
The act of examining photographic images for the purpose of identifying objects and judging their significance.
Photographic Interpretation
usually a coordinate system with its origin in the upper-left corner of the image, the x axis pointing to the right, the y-axis pointing downward, and the units in pixels, as shown by axes c and r in Figure 9. These file coordinates (c, r) can also be thought of as the pixel column and row number, respectively.
Pixel Coordinate System
For a digital image, with origin in the upper-left corner of the image, the x-axis pointing to the right, y-axis pointing downward. P (row, column).
Pixel/File Coordinate System
What is the Exposure Station?
Position of camera at each exposure.
Can use printing paper, plastic film, glass plate. Correct tone & geometry by using negative.
Positive films
is determined by y drawing lines between opposite fiducial marks.
Principal Point
point in the focal plane where the optical axis of the camera pointed during exposure.
Principal Point
the point where the perpendicular projected through the center of the lens intersects the photo image
Principal Point
Describe the phase of plane table photogrammetry
Prior to the invention of the airplane, photographs taken on the ground were used to extract the relationships between objects using geometric principles.
The radiometric quantities are based on the amount of radiant incident to a surface from any angle in a hemisphere (a half of a sphere).
Radiation Budget Equation
mainly consists of scattering from atmospheric gases. This occurs when the particles causing the scattering are smaller in size than the wavelengths of radiation in contact with them. This type of scattering is therefore wavelength dependent. As the wavelength decreases, the amount of scattering increases. Because of Rayleigh scattering, the sky appears blue, as in the picture below. This is because blue light is scattered around four times as much as red light, and UV light is scattered about 16 times as much as red light.
Rayleigh scattering
What are the three types of scattering?
Rayleigh, Mie, Non-selective
What is the process whereby radiation "bounces off" an object like a cloud or the terrain?
Reflectance
What is the bending of light when it passes from one medium to another of different density?
Refraction
Shift in photographic position of image caused by elevation above/below the datum.
Relief Displacement(d)
The measurement or acquisition of information of some property of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object or phenomenon under study.
Remote Sensing
an Earth observation satellite or communications satellite deployed for military or intelligence applications.
Satellite Reconnaissance
Purity / richness of the dominant color components.
Saturation
Represents the boldness of the color.
Saturation
Ratio between photo distance and ground distance
Scale
The electromagnetic radiation to be redirected from its original path when interacting particles or large gas molecules present in the atmosphere.
Scattering
Define Thermal infrared sensors
Sensors that can detect the thermal infrared radiation emitted by surface features can reveal information about the thermal properties of these materials. Like reflected solar sensors, these are passive systems that rely on solar radiation as the ultimate energy source. Because the temperature of surface features changes during the day, thermal infrared sensing systems are sensitive to time of day at which the images are acquired.
The edge of an object, the most fundamental element to identify the object.
Shape
classified as Linear, curvilinear, circular, elliptical, radial, square, rectangular, triangular, hexagonal, pentagonal, star, amorphous, etc.
Shape
The production of what is accomplished in total darkness, by combining silver nitrate and potassium bromide in the presence of gelatin?
Silver Halide Crystals
What are the First Order Elements?
Silver Halide Crystals and Pixels
A camera having only one lens.
Single Lens Mapping Camera
Unique physical and/or socioeconomic characteristics
Site
compares the relationship between an object and its surrounding features.
Site and Situation
Objects are placed, organized in a particular order or orientation relative to one another.
Situation
The adjectives that describe texture
Smooth: Uniform, homogeneous Intermediate. Rough: coarse, heterogeneous
What law states that the sine of the angle of incidence divided by the sine of the angle of refraction equals a constant called the index of refraction when one of the media is air?
Snell's Law of Refraction
the largest thing that can be seen on the ground for a particular image
Spatial resolution
used to determine paper color, brightness, and whiteness, important optical properties that dramatically affect the quality of material printed on the paper surface.
Spectral reflectance curves
What occurs if the average surface profile height is much smaller than the radiation wavelength, all the energy is directed away in a single direction?
Specular Reflection
Describe analog photogrammetry
Starting with stereo measurement in 1901, optical or mechanical instruments were used to reconstruct three-dimensional geometry from two overlapping photographs.
Image positions measured by simultaneous view of overlapping stereo pair of photographs.
Stereo-comparator
Based on the use of pigments or dyes, but not light, caused by subtracting (absorbing) some wavelength of light and reflecting the others
Subtractive Color Theory
gives the direction of the tilt on the photo (0~360 degrees or -180 degrees ~ 180 degrees)
Swing(s)
Unavoidable product of lens manufacture, now is generally very small
Symmetric Radial Distortion
unavoidable, distorted along radial lines from the optical axis
Symmetric Radial Distortion
both occur if light rays are bent, or change directions, so that after they pass through the lens, they do not emerge parallel to their incoming directions.
Symmetric radial and decentering
causes imaged points to be distorted along radial lines from the optical axis
Symmetric radial distortion
Used to make coordinate measurements by mounting the photos and converting from x,y digitizer axes to image axis system
Tablet Digitizer
Taken with ground-based cameras Position and orientation often measured
Terrestrial (close range photogrammetry)
are commonly used for applications involved with archeology, geomorphology, civil engineering, architecture, and industry.
Terrestrial and close-range photographs and images
are taken with the camera stationed on or close to the Earth's surface.
Terrestrial or ground-based photographs and images
The repetition of tonal change that causes the visual impression of roughness and smoothness.
Texture
a function of Scale
Texture
is produced by an aggregate of characteristics too small to be discerned individually
Texture
the frequency of change and arrangement of tones
Texture
What is the Flying Height?
The Altitude of the camera at exposure time.
a horizontal line as the line perpendicular to the principal line. A line through the perspective center perpendicular to the principal plane. The term is arbitrarily restricted to this definition to avoid confusion in usage.
The Axis of Tilt
What can range from the extremely simple, consisting of a trigger mechanism with a disposable camera, to complex apparatus using radio control and digital camera?
The camera rigs
Define Wavelength
The distance between any wave and the next succeeding one.
Define Object Distance
The distance between the point of incidence and the object placed in front of a mirror
a set of cylindrical coordinates in which the height, angle, and radius represent intensity, hue, and saturation.
The intensity-hue-saturation (IHS) system
Define Amplitude
The measure of the height of the crest or depth of the trough.
Define Frequency
The number of waves that pass a given point in a unit of time.
is defined at the perspective center S as shown in Figure 10.
The origin of the image space coordinate system
Define Stereo-pair
The overlapping pair of photos.
What camera is the simplest camera?
The pinhole camera
Define Index of Refraction
The ratio of the speed of light in a vacuum, c, to the speed of light in the substance, Cn The index of refraction can also be explained as the ratio of the velocity of light in one medium to that in another.
Define Velocity
The speed with which a wave moves from a light source.
provide information about surface temperatures and the thermal properties of surface materials.
Thermal infrared images
However, we often can see a horizon in an oblique air photo. What is this horizon called?
This is the apparent horizon.
How does an aerial photograph become tilted?
Tilt is caused by the rotation of the platform away from the vertical. This type of displacement typically occurs along the axis of the wings or the flight line.
When the camera axis is unintentionally tilted slightly from vertical, the resulting photograph is called a
Tilted Aerial Photograph
classified as Bright, dark, and intermediate
Tone
the Degree of lightness or darkness of an object.
Tone
the only information used by digital image classification
Tone
the shades of gray displayed ranging from black to white on a black and white photo
Tone
map depicting terrain relief showing ground elevation, usually through either contour lines or spot elevations.
Topographic Map
includes spot height information, contour lines, and elevation data
Topographic information
graphic representation delineating natural and man-made features of an area or region in a way that shows their relative positions and elevations.
Topographic map
represents the horizontal and vertical positions of the features represented.
Topographic map
Finds coordinates by mathematical calculation; measure distance from the point to 2 fiducials and calculate based on equation. Different measured fiducial distances give different results so compute photo coordinates in more than one independent solution and then average the results.
Trilaterative Method
Because windows introduce no optical power into a system, windows should be selected based on the material transmission properties, optical surface specifications, and the mechanical properties that match your application.
True
Distortion from atmospheric refraction increases when flying altitude increases.
True
If a low order of accuracy is acceptable, an ordinary engineer's scale may prove satisfactory.
True
Intensities of three-color guns (RGB) of the monitors are modulated by the digital number of each pixel.
True
Inward radial distortion is considered negative.
True
Kite aerial photography (KAP) is a hobby and a type of photography.
True
Often because of atmosphere haze or other types of obscuration, the true horizon of a photo cannot really be seen.
True
Outward radial distortion is considered positive.
True
When an area is covered by vertical aerial photography, the photographs are usually taken along a series of parallel passes.
True
When greater accuracy is desired, a device such as the glass scale may be used.
True
photogrammetry has continued to develop over the last 150 years.
True
Using flying height above ground and camera focal length
Variable Terrain
NGVD29, NAVD88
Vertical datum
What are the main atmospheric constituents which absorb radiation?
Water (H20), carbon dioxide (CO2), oxygen (O2), ozone (O3), and nitrous oxide (N2O)
a theory in physics where light is transmitted from luminous bodies to the eye and other objects by an undulatory movement.
Wave theory
line on photo between opposite fiducials which most nearly parallels the direction of flight.
X-axis of the photograph
elevation above mean sea level for a given vertical datum
Z value
What is a topographic map?
a map indicating both horizontal and vertical positions.
the computer replaced some expensive optical and mechanical components.
analytical photogrammetry
What are the units for Speed of Light?
c, which is 3 x 10^8 meters per second (here after referred to as meters per second^-1 ) or 186,282.03 miles s^-1
In a what, the apparent horizon is shown?
high angle oblique
identical to an image coordinate system, except that it adds a third axis (z) to indicate elevation.
image space coordinate system
Define Hot Air Balloon
lighter-than-air aircraft consisting of a bag, called an envelope, which contains heated air.
In a what, the apparent horizon is not shown?
low angle oblique
What does not include the horizon?
low oblique photograph
What are the applications of thermal infrared images?
mapping rock types, soils, and soil moisture variations, and monitoring vegetation condition, sea ice, and ocean current patterns.
Engineer's scales are available in both____________ units and have several different graduation intervals so as to accommodate various nominal scales.
metric and English units
Making precise measurements (Distance, angles, areas, volumes, elevation, sizes, and shapes) from photos and other sources to determine relative location.
metric photogrammetry
occurs in the lower portion of the atmosphere when the particles are much larger than the incident radiation. This type of scattering is not wavelength dependent and is the primary cause of haze.
non-selective scattering
line joining centers of curvature of spherical surfaces of lens.
optical axis
1) aerial photograph that is geometrically corrected. 2) An aerial photograph that has been modified so that its scale is uniform throughout.
orthophoto
A model that describes the arrangement and movement of particles in a substance. The model is used to explain the physical properties of solids, liquids, and gases.
particle theory of matter
The art, science, and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring, and interpreting photographic images and patterns of electromagnetic radiant imagery and other phenomena.
photogrammetry
A particle representing a quantum of light or other electromagnetic radiation. Carries energy proportional to the radiation frequency but has zero rest mass.
photon
In one of the sides of the what is a small hole which, via the rectilinear propagation of light, creates an image of the outside space on the opposite side of the box?
pinhole camera
The file coordinates of a digital image are defined in a
pixel coordinate system.
a map indicating only the horizontal positions of features, without regard to elevation.
planimetric map
The origin of the image coordinate system is referred to as the
principal point
What are the two types of lens distortion?
radial and tangential lens distortion.
also commonly referred to as symmetric lens distortion.
radial lens distortion
causes imaged points to be distorted along radial lines from the principal point o.
radial lens distortion
a curve that illustrates the reflectance of light from a surface, such as paper, wavelength-by-wavelength throughout the visible spectrum, as a means of determining the color of that surface.
spectral curve
Adjectives that describe pattern
systematic or random Linear, curvilinear, rectangular, circular, elliptical, parallel, centripetal, serrated, striated, braided
occurs at right angles to the radial lines from the principal point.
tangential lens distortion.
Define Stereoscopic Overlap Area
the area of coverage common to an adjacent pair of photographs in a flight strip
What is visible light?
the portion of electro-magnetic (E-M) radiation (EMR) that is visible to the human eye
On aerial photographs, what point is defined as the intersection of opposite fiducial marks as illustrated by axes x and y in Figure 9?
the principal point
The shorter the object distance, the larger
the scale.
Primary function of Lenses
to focus light while allowing more radiation through than pinhole, thus allowing photography; gather light rays from object space and bring them to focus on an image plane Employs principles of refraction.
Outputs of analytical photogrammetry
topographic maps, but also can be digital products, such as digital maps and Digital Elevation Models
Band-pass Filter.
used to pass (transmit) a range of wavelengths and to block (reflect) other wavelength on either side of the bandpass.
Image coordinate units
usually millimeters or microns.
If the image is zero, the image must be
vertical
line on photo normal to x-axis with positive being 90 degrees counterclockwise from +x
y-axis
Physical site characteristics
· Elevation · Slope · Aspect · Exposure
socioeconomic site characteristics
· Value of Land · Land Tenure System · Adjacency to Water · Transportation · Utilities adjacent to Water
Define Emulsion
1) Contains light-sensitive silver halide crystals. These are placed on the backing or support in a thin coat. 2)The support material is usually paper, plastic film, or glass.
What are the advantages of an oblique aerial photograph?
1) Given a constant altitude and camera you can cover a much larger area on a single photo. 2) The view of some objects is more familiar to the interpreter. 3) Some objects not visible on vertical photos may be seen on oblique.
What are the Two components of a pinhole camera?
1) Light 2) Dark room (camera)
What are the two branches of Interpretative Photogrammetry?
1) Photographic interpretation: study of photographic images. 2) Remote sensing: analysis of images and use of the data gathered from wide range of sensors.
Define Photo Block
1) photos of 2 or more side lapping strips used to cover an area. 2) The photographs of two or more side-lapping strips are used to cover an area.
What are the most common applications of metric photogrammetry?
1) the preparation of planimetric and topographic maps from photographs 2) the production of orthophotos from digital imagery.
What is the Side Lap?
1)Adjacent flight strips overlap (15%). 2)Adjacent flight strips are photographed so that there is also a lateral overlapping of ground coverage between strips.
Define Camera Obscura
1)a box-shaped device used as an aid for drawing or entertainment. 2)Also referred to as a pinhole image, it lets light in through a small opening on one side and projects a reversed and inverted image on the other.
Define Pinhole Camera
1)also known as Camera obscura, or "dark chamber", 2)is a simple optical imaging device in the shape of a closed box or chamber.
What are the basic applications of metric photogrammetry?
1. The Preparation of planimetric and topographic maps 2. The Production of orthophotos
How many Fiducial Marks represent the corners or center of sides?
4 marks
How many Fiducial Marks represent the corners and center of sides?
8 marks
can be influenced by the image scale, i.e., coarse texture on a large-scale photo might be a smooth texture on a small-scale photo.
A Feature's texture
an information system designed to provide the decision maker with the most current, accurate and complete data about phenomenon or events within an area.
A GIS
includes the horizon
A high oblique photograph
what are Flight Strips?
A series of parallel passes followed when taking photographs.
What is Radian energy at various wavelengths that is consumed and converted into other form of energy in the atmosphere or terrain?
Absorption
What is a range of wavelengths in the spectrum within which radiant energy is absorbed by a substance?
Absorption band
Haze Filter
Absorb wavelengths shorter than 400 nanometers. Eliminate the scattering of ultraviolet radiation caused by atmospheric haze. Useful for collecting natural color aerial photography.
What is Used to display images on TV and computer monitors?
Additive Color Theory
based on what happens when light is mixed and a pixel having RGB values of 255, 255, 255 produces a bright white pixel.
Additive Color Theory
A camera specially designed for use in aircraft. The prefix aerial is not essential where the context clearly indicates the use of an aerial camera rather than a ground camera.
Aerial Camera
The making of photographs of the ground surface from an aircraft, spacecraft, or rocket.
Aerial Photography
Platforms for aerial photography include fixed-wing aircraft, helicopters, unmanned aerial vehicles (UAVs or "drones"), balloons, blimps and dirigibles, rockets, pigeons, kites, parachutes, stand-alone telescoping and vehicle-mounted poles. Mounted cameras may be triggered remotely or automatically; hand-held photographs may be taken by a photographer.
Aerial platform
Who patented a rocket camera in 1903?
Albert Maul
Magnitude of Relief Displacement
Amount of relief increases the farther the point is with respect to the principal point. Greater the elevation the greater the amount of relief displacement. Increasing flying height decreases the amount of relief displacement.
Is a tilted aerial photograph good or bad?
An aerial photo becomes tilted due to unavoidable aircraft tilts. While it is not a good thing, precise photogrammetric instruments and procedures have been developed that make it possible to rigorously account for tilt with no loss of accuracy.
defined as a two-dimensional (2D) coordinate system occurring on the image plane with its origin at the image center.
An image coordinate system or an image plane coordinate system
Point by point rectification. Need ground control point. 2-D projective transformation where X, Y are the ground coordinates, x, y are image coordinates.
Analytical (Numerical) Rectification
Used to perform the function of both mono-comparators and stereo-comparators when working directly with film.
Analytical Stereo-plotter
As what increases, f-stop numbers decrease and illuminance increases, thus requiring less exposure time, i.e., faster shutter speeds?
Aperture
What is the opening in a lens through which light passes to enter the camera?
Aperture
Related phenomena are usually present if you find a certain phenomenon
Associations
Caused by changing density of atmosphere.
Atmospheric Refraction
Causes all image points to be displaced outward from their correct positions.
Atmospheric Refraction
Light rays coming from the surface are bent as they travel through the atmosphere and causes all imaged points to be displaced outward from their correct positions. The higher the flying distance, the greater the distortion.
Atmospheric Refraction
Magnitude increases with increasing flying height and increasing α angle.
Atmospheric Refraction
What is the cumulative effect of the absorption by the various constituents can cause the atmosphere to close down in certain regions of the spectrum?
Atmospheric close down
What is caused by the scattering of ultraviolet and short blue wavelengths?
Atmospheric haze
gives the orientation of the principal plane with respect to the ground reference (0~360 degrees or - 180 degrees ~ 180 degrees)
Azimuth
What problems does correcting for this distortion cause?
Because of the nature of map projection coordinates, correcting photo coordinates for the curvature of the earth will degrade the accuracy of either the X or Y object space coordinates, depending on the projection.
Ancillary information about the subject and the study area
Collateral information
May be defined as each distinguishable variation on an image produced by a multitude of combinations of hue, value and chroma.
Color
What are the Second Order Elements?
Color and Tone
For direct measurement of film giving the ultimate in photo coordinate measurement accuracy.
Comparator
used primarily to obtain precise photo coordinates necessary for camera calibration and for analytical photogrammetry. Their accuracy capability is typically in the range of from 2 to 3 micrometers (μm).
Comparators
Principal Point (PP) from adjacent photo in flight line
Conjugate Principal Point
are the locations of principal points on adjacent overlapping photos.
Conjugate Principal Point
Work from known to unknown
Convergence of Evidence
What is another word for Conjugate Principal Point?
Corresponding principal point
A reference from which the measurements are made
Datum
Due to an imperfect assembly of lens elements, not actual lens design
Decentering Distortion
What causes an off-center distortion pattern?
Decentering distortion
Degree of lightness or darkness of an object.
Degree of Tone
It is the shades of gray displayed ranging from black to white on a black and white photo.
Degree of Tone
What occurs if the surface height is larger relative to size of the wavelength, the reflected rays go in many directions?
Diffuse Reflection
Senses light energy using semiconductor electronics instead of film.
Digital Camera
Computer processing. Ground control points. Transformation from image coordinates to ground coordinates (several models).
Digital Rectification(geo-referencing)
Elevation of exposure station above sea level or datum The Altitude of the camera at exposure time
Flying Height(H)
employ sophisticated software to automate the tasks associated with conventional photogrammetry, thereby minimizing the extent of manual interaction required to perform photogrammetric operations.
Digital photogrammetric systems
The output products are in digital form, such as digital maps, DEMs, and digital orthoimages saved on computer storage media.
Digital photogrammetry
photogrammetry applied to digital images that are stored and processed on a computer.
Digital photogrammetry
sometimes called softcopy photogrammetry
Digital photogrammetry
Define Image Distance
Distance from lens center to image plane.
Corrections applied to photo coordinates to compensate for the effects of earth curvature. However, it may degrade accuracy of object space coordinates depending on underlying map projection used.
Earth's Curvature
What is the transmission of energy in the form of waves having both an electric and a magnetic component?
Electromagnetic Radiation
a form of energy exhibiting wave like behavior as it travels through space.
Electromagnetic Radiation
has both electric and magnetic field components, which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation.
Electromagnetic Radiation
X, Y location; tone/color; size; shape; texture; pattern; height/depth/volume/slope/aspect; site/situation/association
Elements of Image Interpretation
Used for lower accuracy measuring requirements and have several different graduation intervals to accommodate various nominal scales.
Engineer Scale
space position of the front nodal point at the instant of exposure Position of camera at each exposure
Exposure Station(L)
What is the ratio of focal length to the diameter of the lens opening, or aperture?
F-stop
This intersection actually rarely happens; manufacturers attempt to mount the lens and the fiducial marks so that these 2 elements coincide but they are always off by some amount that must be corrected for
Failure of Fiducial Axes to Intersect at PP
rigidly fixed marks that define the frame of reference for mapping cameras.
Fiducial Marks
What are some ways to obtain x, y coordinates?
Field Surveying, such as Traditional field survey and/or the Global positioning system. Rectified Image, where the user Extracts x, y coordinates information directly from the rectified image.
Due to expansion or contraction of photographic film and the resulting lack of flatness
Film Distortion Error
What allows only certain wavelengths of light through lens and "subtracts" some of the light reflected from a scene before it reaches the lens?
Filters
Terrain where topographic variation ≤ 5% flying height.
Flat Terrain
Light rays that are parallel to the optical axis as they enter a lens come to focus
Focal Point
A framework that is used for the observation and mathematical description of physical phenomena and the formulation of physical laws, usually consisting of an observer, a coordinate system, and a clock or clocks assigning times at positions with respect to the coordinate system.
Frame of Reference
a set of coordinates that can be used to determine positions and velocities of objects in that frame; different frames of reference move relative to one another.
Frame of Reference
Greater accuracy than the engineer scale; readings can be estimated to 1/10th of the smallest division but these scales cannot be used to lay out distances.
Glass Scale
What can be obtained in either 6- or 12-inch length with either millimeter graduations (least graduations of 0.1 millimeter) or inch graduations (least graduations of 0.005 inches)?
Glass scales
What has fine graduations etched on the bottom surface and are equipped with magnifying eyepieces which can slide along the scale?
Glass scales
A location on the surface of the Earth (e.g., a road intersection) that can be identified on the imagery and located accurately on a map.
Ground Control Point (GCP)
usually expressed in feet or meters.
Ground coordinates (X, Y, Z)
3-D coordinate system that utilizes a known geographic map projection.
Ground/Object Space Coordinate System
NAD27, NAD83, WGS84
Horizontal datum
Color determined by the dominant wavelength.
Hue
Represents the specific mixture of wavelengths that define the color.
Hue
The examination of images for the purpose of identifying objects and judging their meaning or significance - not just photo reading.
Image Interpretation
the process making vertical photographs from tilted photos.
Image Rectification
3-D coordinate system. The origin is defined the perspective center.
Image Space/Sensor Coordinate System
used to describe positions on the film plane
Image coordinates
Two distinct sets of coordinates associated with each GCP need to be obtained
Image coordinates Ground coordinates
include not only the analysis of photography, but also the use of the data gathered from a wide variety of sensing instruments, including multispectral cameras, infrared sensors, thermal scanners, and side-looking airborne radar.
Image interpretation and remote sensing
Defined as a two-dimensional (2D) coordinate system occurring on the image plane with its origin at the image center (PP).
Image/photographic (plane) coordinate system
When was photogrammetry invented?
In 1851 by Colonel Aimé Laussedat
Who found that when light interacts with matter, it behaves as a stream of many individual bodies called PHOTONS, which carry such particle-like properties as energy and momentum?
In 1905 Albert Einstein
What is the difference between a vertical and oblique aerial photograph?
In a vertical aerial photograph, the camera axis is as nearly vertical as possible, less than 3 degrees. Practically, the camera axis is rarely perfectly vertically, leading to tilted photographs. In an oblique aerial photograph, the camera axis is intentionally tilted.
Define Reflected Infrared
In remote sensing, infrared which is solar-generated electromagnetic radiation that has been reflected from an object. Characteristically, reflected infrared radiation has a wavelength between 0.7 μm and 3 μm and is therefore near-infrared.
Who conceptualized Electromagnetic Radiation (EMR) as an electromagnetic wave that travels through space at the speed of light?
In the 1860s, James Clerk Maxwell (1831-1879)
Define Thermal Infrared
Infrared radiation which has a wavelength between 3.0 μm and 100 μm. At normal environmental temperatures objects emit infrared between these wavelengths; hotter objects, such as fires, emit infrared at wavelengths shorter than thermal infrared.
Lightness and darkness of the color (i.e., tone).
Intensity
Represents overall brightness irrespective of color.
Intensity
deals principally in recognizing and identifying objects and judging their significance through careful and systematic analysis.
Interpretative Photogrammetry
has to do with Recognizing and identifying objects and judging their significance through careful and systematic analysis.
Interpretative Photogrammetry
is included in the branches of image interpretation and remote sensing.
Interpretative Photogrammetry
The point on the photo that falls on a line half- way between the principal point and the Nadir point
Isocenter
Is a tilted aerial photograph common?
It is common since the camera axis is rarely perfectly vertical at time of exposure.
Why is correcting for the Earth's curvature controversial?
It is controversial because horizontal coordinate systems such as state plane systems are curved only in one direction, meaning that the practice of making curvature corrections is not theoretically correct; however, these results were felt to be more accurate than ignoring the curvature, especially in determining elevations.
