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1
Q

what is the two passes of the chain method and what do they collect

A

1st pass spectral building- program reads through dataset and builds clusters.
the analysis provides 4 things radius, space dust par, number of pixels and max number of clusters.

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2
Q

what is remote sensing

A

remote sensing is the science of aQURINGING INFORMATION ABOUT THE EARTHS surface without actually being in contact with it. This is done by sensing and recording reflected or emitted energy and processing, analysing and applying that information.

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3
Q

what are the threee remote sensing detectors

A

RADAR radio detection and ranging
LIDAR light “ “
SONAR sound navigation “ “

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4
Q
A

often cheaper than in place sensing and collects data consistently and synoptically

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5
Q

what are some advantages of remote sensing

A

passive sensors are unobtrusive
no sampling bias and collect data systematically
only tech that can provide data over a very large area of geographic land

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6
Q

what are some limitations of remote sensing

A

often oversold
humans may select the wrong sensors
can become uncalibrated
often very expensive

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7
Q

what is ancillary/collateral data

A

additional information that is added to data and transported using the same form as the original. e.g. datasoil maps, dems, political boundaries

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8
Q

what is in-situ data

A

data not collected by the satellites
often necessary field techniques
calibrations accuracy with gps
often includes the use of transducers

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9
Q

what are sources of error for insitu data

A

intrusive error-shadow soil compactions, trampling
baised sampling design
improper operation of device
instrument not calibrated

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10
Q

what is the difference of passive and active sensors

A

active sensors emit energy passive receive reflected energy

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11
Q

what are the 4 different types of resolution

A

temporal
radiometric
spatial
spectral

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12
Q

what is spectral resolution

A

ability of a sensor to define fine wavelength intervals (bands)
multispectral- 8 bands
hyper spectral- 288 bands
ultra spectral- over hundreds

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13
Q

what is spatial resolution

A

size of area on the ground represented by one pixel worth of energy measurement.
defined in m
IFOV- instantaneous field of view

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14
Q

what is radiometric resolution

A

ability to discriminate very slight differences in energy
how many shades there are
2 vs 8 bit

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15
Q

what is temporal resolution

A

how often it records imagery of a particular area.

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16
Q

what are 4 examples of sensor platforms

A

insitu- cherry picker
airborne- AVIRIS
UAV- fly under clouds on demand but expensive, government restrictions
satelites

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17
Q

what is a analogue conversion

A

image- any pictorial representation
photograph- images recorded on film
pixel-smallest- 2-D element that is the smallest non-divisable element of digital image

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18
Q

what are digital numbers

A

the amount of radiance being measured at the sensor for that section of ground.
each pixel has its own digital number
8 bit os 255 range
aka brightness value

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19
Q

what is a scanning system

A

sensor with narrow swath for that sweeps over terrain to produce 2D image of surface

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20
Q

what are the two types of scanning systems and what are the main differences

A

across track/descrete detectors
rotating mirror to scan the Earth in lines perpendicular to the sensor’s motion.better quality but slower

along track/linear array
use forward motion of platform to record successive

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21
Q

what is an orbit

A

path followed by a satellite they can vary by altitude orientation and rotation relative to earth

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22
Q

what is a geospatial orbit

A

high altitude and matches earths orbit. collect data continuously over an area
mostly for camps and weather

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23
Q

what is a near polar orbit

A

north south in conjunction with earths orbit
northward has ascending shadows southward has sunlit side imaging
sun synchronis- cover each area at constant local time

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24
Q

what is a swath

A

the area imaged on the surface

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25
what are the two main satellites
landsat and spot spot is French and has a better spatial resolution
26
what are some univariate image stats
mode, median, mean, range, variance, std dev, skewness (asymmetry of histogram) kurtosis (weakness of curve)
27
what are some example of multivariate stats
covariance (joint variation of two variables) Pearsons product moment correlation coefficient.
28
what is density slicing
conversion of the continuous tone of an image to a series of discrete class intervals or slices can be either natural breaks, equal size or equal area intervals
29
what is a false colour composite
when the rib bands are replaced with different bands and looks different to irl also colour infrared 4,3,2
30
what are the two main geoprocessing techniques
geometric correction radiometric correction
31
what is geometric correction
placing the reflected, emitted or backscatter measurements in their proper map locationh
32
what is radiometric correction
improving the accuracy of surface specular reflectance, emittance or backscatter measurements obtained using a RS system
33
what are the two types of errors that come from imagery
internal- sensor itself predictable and constant external- atmosphere and scene changes. use GCP
34
how does radiometric correction correct the sensor system detection error
random bad pixels (randomly distributed pixels with no value. to fix use mean of pixels around it partial line or column dropouts (LANDSAT 7) line start problems failed to correct pixel at beginning of the scan line n-line striping sensor out of adjustment
35
radiometric correction atmospheric correction methods of correction
model atmosphere model with in-situ data-local characteristics (absolute) minimisation-using multiple looks at the same object (relative)
36
what is target and path radiance
path 1 very little attenuation path 2 never reaches the surface path 3 Rayleigh or mie scattering path 4 reflected and scattered into IFOV path 5 adjacent area reflected up and bounced back to study area
37
what is the equation for radiance
Ls(total radiance at sensor)=Lt(total radiance from target + Lp(path radiance 9TRY TO REMOVE THIS))
38
what are the three types of scattering
Rayleigh- gas molecules mie- aerosols non selective- closest to surface
39
what is the empirical approach to radiometric normalisation
using targets that do not change between dates
40
what is the main use feature of geometric correction
ground control points
41
what is spatial interpolation
geometric relationship between input pixel location (row/column) and associative map coordinate of same point (x,y) then relocate every pixel in original (x,y) to proper position in output image
42
what are the three methods of intensity interpolation
nearest neighbour bilinear interpolation (looks at 4 nearest pixels and gives BV based on weighted distances) cubic convolution (same as above but uses 16 surrounding pixels
43
what is an enhancement
The alteration of the appearance of an image in a way that the info is easily interpreted by the viewer
44
what are the two different operations in relation to enhancements
point operations (modify each pixels BV independently local operations (modify each pixel in context of the surrounding BV more fuzzy)
45
difference between image reductions and magnifications
reductions zoom out 36 square to 9 square modifications zoom in multiple pixels form from the same original pixel
46
what is a contrast enhancement
alters the range of BV shows greater difference in small BV differences
47
what is a linear contrast enhancement
only considers max and min best for normal distribution start of rise happens at start of bell curve then at end of bell curve all numbers are 255
48
what are the two non linear enhancements
histogram equalization logarithmic (greatest impact on darker BV values)
49
what is spatial filtering
method for selectively emphasising or suppressing info at different spatial scales
50
what is low frequency filtering
local sharp fluctuations are removed. de-emphases the high frequency details.
51
what are the types of low frequency filtering
moving average filter (box the outliers) median filter(create a box around number and pick median of that box
52
what is high frequency filtering
enhance high frequency local variations
53
what is band ratioing
reduces the effect of BV's from identical surface material
54
what is a vegetation indexes
measure vegetation amount and condition
55
types of vegetation indices
SR NDVI Sr is better than NDVI for separating high end biomass but not as good for low end biomass
56
what are the 5 types of classification
hard crisp classification (create a map with descrete categories) Fuzzy set (soft) classification (considers heterogeneity and imprecise nature of the world) Geographic object based image analysis (GEOBIA) not a per pixel classification Numeric methods- Numeral networks Hybrid with ancillary data
57
what is a training site
homogeneous area representing a specific land cover or land use class of interest
58
what is feature selection
select the bands that best asssist in discriminating classes
59
what is the difference between commission and omission error
commission- pixel assigned to a class to which it does not belong omission error pixel not assigned to a class to its appropriate class
60
what is parallelepiped classification
boolean logic cream mean vectors for each class in each band then use std dev for class selection
61
what is minimum distance to means classification
euclidean distance to the closest class
62
nearest neighbour classification
use actual training data BV in each band and nearest neighbour distance measures aka kmeans
63
max likelihood classification algorithm
assumes norm distance based on probabilities determines probabilities for each class then assigns them
64
what is the isolate classification method
self organised select c max clusters numbers t max, M number of times it classifies pixel
65
what is fuzzy classification
based on imprecise geographic info. hard classifier (yes=1, no=0)
66
what is GEOBIA
2 procedures first is object oriented image segmentation second is traditional classification to the objects

remote sensing (1 decks)

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