Photogrammetry and Remote Sensing University of Montana Test 1
Question
Answer
Passive Remote Sensing
The sun is the primary source of energy. Detector makes sensing data.
Name two types of passive remote sensing.
Solar and terrestrial.
Active Remote Sensing
Sensor has its own source of energy.
Name two types of active remote sensing.
RADAR and LIDAR
What role does physics play in remote sensing?
It helps us understand inputs into the system.
What three things happen when energy reacts with the target?
It's absorbed, transmitted, and reflected.
Kirkov's Law states that
absorbed + transmitted + reflected = 1
At the sensor
reflection = 1 - absorbed
How do we take into account energy matter interactions when we collect our data?
We collect our data when these things are normalized.
the science and art of obtaining information about an object through analysis of data acquired by a device not in contact with the object.
Remote sensing
What are six advantages of remote sensing?
Improved synoptic vantage point, Provides 3D views, Capability to stop action, Provides a permanent record, enhanced spectral sensitivity, variable resolutions.
Name three types of information that can be sensed?
Planimetric location, topo elevation, and color.
What is electromagnetic energy (EMR)?
Energy flowing as a wave at the speed of light.
What wavelength is ultraviolet light?
10nm - 1000nm
What wavelength is visible light?
400nm - 700nm
What wavelength is infrared light?
1000nm - .01cm
What wavelength is microwave/radar?
1cm - 1m
What are two problems that are associated with the earth's atmospheres? (remote sensing)
Scattering and absorption.
What is an ideal remote sensing system?
A uniform energy source, a non-interfering atmosphere, unique energy / matter interactions, a super sensor, a real time data handling system, and multiple data users.
What are the errors associated with maps?
"DADS", distance, direction, area, and shape.
What are the three families of mapping projections?
Planar / Azimuthal, Conic, Cylindrical, and hybrid.
Map
A 2-D graphic of points, lines and polygons. That portrays spatial relationships of earth features at a reduced scale according to systematic rules.
What are four properties of an ideally projected map?
Conformality, equivalence, equidistant, and true direction.
Conformality
true shape
Equivalence
equal area
Equidistant
true distance measuring
True direction
thumb lines or loxidromes exist, lines of constant bearing
What maps are best suited to contain all ideal projected map properties?
Very large scale maps, or maps of small areas.
What causes map distortion?
The geometric relationships on the sphere cannot be entirely duplicated on a plane.
Topology
spatial relationships between mapped entities or features.
Graticule
a set of longitude and latitude lines.
Loxidrome
any straight line.
Conformal
true shape, cylindrical projection.
An example of a conformal projection is
mercader
Developeable
something that can be changed from 3D to 2D
Planar
pie shaped squares
Cylindracal
squares and rectangles
Conic
kind of like planar but different
Transverse
tangent to equador
When is distortion minimized?
when projection is tangent to the globe
Equivalence preserves areal relationships but not
shapes
When making maps you generally need to choose
ellipsoids, datums, and projection types.
Coordinate system
used to define location on a sphere or plane.
Datum
a geodetic reference system that specifies the size and shape of the earth, and the base point from which the latitude and longitude of all other points on the earth's surface are referenced.
Nomic
earth centered
DMS
Degrees Minutes Seconds (LAT/LONG)
LAT/LONG of (0,0) represents what place?
Greenwich Meridian (AKA Prime Meridian) -- Goes through Greenwich, England.
Universal Transverse Mecader
60 zones, square grid, false origins, metric base 10 system, cuts 6 degree strips out for each zone.
Township
designates north / south of baseline (prime meridian)
Range
designates east / west of baseline (prime meridian)
What is included in a full legal description?
State, prime meridian name, township, range, section and subsection.
PLSS is what kind of mapping system?
Cartesian
What is the problem associated with PLSS?
It is a flat Cartesian system on a curved surface.
What are the three north references?
True, grid, and magnetic.
True North
The direction to the north pole of the axis of the earth rotation.
True North Baseline
A line from any point on the earth to the north pole.
Grid North
The grid orientation direction on a map (up).
Magnetic North
Utilizes earths magnetic field, is the direction a compass points to.
Declination
The difference between true north and magnetic north.
Agonic line
The line of no declination
Mil
1/6400 of a circle
False origin
Prevents negative X and Y values.
Wavelength
Distance from peak to peak on SIN function.
Amplitude
Distance from bottom of wave trough to top of wave peak on a SIN function.
Frequency
the number of wave peaks passing a fixed point in unit time.
How are frequency and wavelength related?
Speed of Light = Wavelength X Frequency
What are the three regions of IR?
Near IR, Mid IR, and Thermal IR
What is the relationship between energy and wavelength?
The greater the wavelength the less the energy.
Photon
A pulse of energy
How is photon energy related to wavelength?
Energy in a photon is inversely proportional to its wavelength.
Why are energy relationships important to remote sensing?
At long wavelengths there is little energy to sense. We have to "sense" large areas to have sufficient energy. Sensing a large area results in lower spatial resolutions. In the VIS region of the EM, we can sense areas < 10M, MICRO >10M.
Black Body
Perfect emitters and absorbers of radiation and radiate the maximum amount of energy for their temperature. (Theoretical)
What is the emissivity of a gray body?
E < 1
What is the emissivity of a black body?
E = 1
Emissivity
The ability of a material to emit radiant energy and it's efficiency in radiating energy.
Planck's Law
This function represents the emitted power per unit area of emitting surface, per unit solid angle, and per unit frequency.
Stefan-Boltzman Law
states that the total energy radiated per unit surface area of a black body in unit time is directly proportional to the fourth power of the black body's thermodynamic temperature.
HHS Shrek
