Midterm Flashcards
better term for in situ data than “ground truth”
in situ ground reference data (since it also contains error)
remote sensing is both a ___ and a ___
art, science
the EMR reflected, emitted, or back-scattered from an object or geographic area is used as a ____ for the actual property under investigation
surrogate
3 active remote sensing techniques
LIDAR, RADAR, SONAR
most expensive part of a remote sensing system
people
way radiometric resolution is measured
EMR may be used as a ___ for the actual property under investigation
surrogate
remote sensing is both a ___ and an ____
science, art
Radiometric resolution
color depth or number of values that can be used for a single pixel (1 bit = 2^1 = 2 possible color values….8 bit = 2^8 = 256 possible color values)
rows
sideways (i), y-axis
columns
up and down (j), x-axis
aproximate wavelengths of landsat 8 bands (just B,G,R, NIR) in micrometers
B = 0.45 - 0.51
G = 0.53 - 0.59
R = 0.64 - 0.67
NIR = 0.85 - 0.88
BIP, BIL, and BSQ
population
infinate or finite set of elements
sample
subset of the elements taken from a population used to make inferences about certain characteristics of the population
sampling error
the difference between the true value of a population characteristic and the value of that characteristic inferred from a sample
median
value midway in the frequency distribution. one-half of the area below the ditribution curve is to the right fo the median, and one-half is to the left
relationship between variance and standard deviation
The square root of variance is called the standard deviation.
a high kurtosis value means a high _____ compared to a normal distribution
peak
covariance
joint variation of two variables about their common mean
Kriging
weights the surrounding measured values to derive a prediction fro each new location
variography
process whereby a spatially depended model is fit to the data and the spatial structure is quantified
semivariance
provides an unbiased description of the scale and pattern of spatial variability throughout a region
two distinct tasks involved in kriging
- quantifiying the spatial structure of the surrounding data points
- producing a prediction at a new location
standard deviation
the standard deviation is found by taking the square root of the average of the squared differences of the values from their average value
difference between scientific visualization and presentation graphics
The difference between scientific visualization and presentation graphics is that the latter are primarily concerned with the communication of information and results that are already understood. During scientific visualization we are seeking to understand the data and gain insight.
bitmapped
The digital image processing industry refers to all raster images that have a pixel brightness value at each row and column in a matrix as being bitmapped images.
For example, the simplest bitmapped image is a binary image consisting of just ones (1) and zeros (0).
color theory used with light
additive color theory (For example, in additive color theory a pixel having RGB values of 255, 255, 255 produces a bright white pixel)
color theory used with pigment
subtractive color theory (mixing more pigments produces darker images)
optimum index factor
The largest OIF will generally have the most information (as measured by variance) with the least amount of duplication (as measured by correlation)
two most common types of error encountered in remotely sensed data
radiometric and geometric
radiometric correction attempts to…
improve the accuracy of spectral reflectance, emittance, or back-scattered measurements obtained using a remote sensing
geometric correction is concerned with …
Geometric correction is concerned with placing the reflected, emitted, or back-scattered measurements or derivative products in their proper planimetric (map) location so they can be associated with other spatial information in a geographic information system (GIS) or spatial decision support system (SDSS).
Radiometric and geometric correction of remotely sensed data are normally referred to as
preprocessing
internal errors (those produced by the remote sensing system) are generally ____ in nature
systematic, predictable
external errors are introduced by
phenomena that vary in nature through space and time
three basic ways energy is transferred
conduction (one transfers its kinetic energy to another by colliding with it)
convection (transfer through liquids or gasses)
radiation (tranfer through a vacuum)
some of the sun’s energy is reflected as ____ wave energy and some is absorbed and later emmitted as ____ wave energy
short, long
as the temperature of an object increases, its dominant wavelength…
…shifts toward the shorter wavelenths of the spectrum (thus it’s possible to determine the temperature of an object based on its dominant wavelenth!)
wien’s displacement law simplified with sun used as example
dominant wavelenth = wein’s constant (2898 um K) / absolute temperature
e.g. the sun’s dominant wavelegth is .483 micrometers (green!) so
.483 um = 2898 um K / 6000 K
% of sun’s energy that is ultraviolet, visible, and infrared
ultraviolet = 9%
visibit = 41%
infrared = 50%
wavelength range of visible light
.4 to .7 micrometers
or 400 to 700 nanometers
Stefan-boltzmann law
the total emitted radiation from a blackbody is proportional to the fourth power of its absolute temperature
or
total emmitted radiation = 5.666 x 10^-8 W m^-2 x Temperature^-4
4 step remote sensing process
statement of the problem
data collection
data-to information conversion
information presentation
collateral data
digital elevation models
soil maps
surficial geology maps
population density, etc
3 types of transformation
RGB to IHS transformation and back again
Chromaticity Color Coordinates system
Brovey Transformation
IHS stands for
intensity, hue, saturation
chromaticity color coordinate system
color space consisting of two independant parameters, often specified as hue and colorfulness
the coordinates of the chromaticity diagram represent the relative fractions of each of the primary colors (RGB) present in a given color.
intensity, hue, saturation
intensity varies from black (0) to white (255) and is not associated with any color.
hue represents the circumference of the sphere, which is the dominant wavelength of color
saturation represents the purity of the color and ranges from 0 at the center of the color space to 255 at the circumference. a saturation of 0 represents a completely impure color which will appear as a shade of grey.
Brovey transform
may be used to merge (fuse) images with different spatial and spectral characteristics. It is based on the chromaticity transform and is a much simpler technique than the RGB-to-IHS transformation. The Brovey transform also can be applied to individual bands if desired.
basically a resolution merge
Relative vs. absolute correction
Empirical line calibration can be relative or absolute. Relative correction matches 2 images. Absolute ends up with radiance values.
