11/13/23, 1:55 AM GEOS2161 Final Exam Weeks 1 to 11
GEOS2161 Final Exam Weeks 1 to 11 | 117 Questions And
Answers updated graded A
unsupervised classification
Digital information extraction technique in which the computer assigns pixels to categories with no
instructions from the operator.
Unsupervised classification advantages and disadvantages
advantages:
- no extensive prior knowledge of the area is required
- opportunity for human error is minimised
- unique classes are recognised as distinct units
disadvantages:
- analyst has little control of the classes and their specific identities
- spectral properties may change over time
- requires the analyst to match spectral classes generated to the land use categories of interest
Supervised classification
- Digital-information extraction technique in which the operator provides training-site information that
the computer uses to assign pixels to categories.
- analyst uses knowledge of the area to guide the classification
Classification Method: minimum distance to means
classifies each pixel of unknown land cover class to the category whose mean brightness value lies
closest
Classification Method: maximum likelihood
classifies each pixel of unknown land cover class to a land cover category on the basis of probability.
Assumes training data are normally distributed
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,11/13/23, 1:55 AM GEOS2161 Final Exam Weeks 1 to 11
drones
- 'third generation source of remote sensing'
- agriculture, emergency services, atmospheric sciences
Big Data
refers to spatial data sets exceeding the capacity of current computing systems
Thematic maps
- a map of a theme or topic (rainfall stations, land use, geology)
Dot maps
- used to represent discrete phenomenon or themes that vary smoothly over space
- example: livestock farms, population distribution in a region
Choropleth maps
- shows regions or ranges which have the same characteristics represented with colours example:
population density
Proportional symbol map
A map that uses symbol in proportion to the value of the phenomenon it is representing.
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, 11/13/23, 1:55 AM GEOS2161 Final Exam Weeks 1 to 11
Dasymetric maps
Usually used to show population distribution using boundaries that divide the area into zones.
Isopleth maps
maps that have lines that connect points of equal intervals, often used for temperature, dew point etc
(isotherms/isobars/etc.)
three methods of division
1. equal interval
2. equal count or percentile
3. natural breaks
Equal interval method
Divides attribute values into equal size ranges. Often used to depict population on a choropleth map
density, crime rates, etc.
Equal Count or Percentile Method
data is divided percentiles, and are generally unequal
Natural Breaks Method
data is divided into classes based on natural breaks observed in data histogram
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GEOS2161 Final Exam Weeks 1 to 11 | 117 Questions And
Answers updated graded A
unsupervised classification
Digital information extraction technique in which the computer assigns pixels to categories with no
instructions from the operator.
Unsupervised classification advantages and disadvantages
advantages:
- no extensive prior knowledge of the area is required
- opportunity for human error is minimised
- unique classes are recognised as distinct units
disadvantages:
- analyst has little control of the classes and their specific identities
- spectral properties may change over time
- requires the analyst to match spectral classes generated to the land use categories of interest
Supervised classification
- Digital-information extraction technique in which the operator provides training-site information that
the computer uses to assign pixels to categories.
- analyst uses knowledge of the area to guide the classification
Classification Method: minimum distance to means
classifies each pixel of unknown land cover class to the category whose mean brightness value lies
closest
Classification Method: maximum likelihood
classifies each pixel of unknown land cover class to a land cover category on the basis of probability.
Assumes training data are normally distributed
about:blank 1/20
,11/13/23, 1:55 AM GEOS2161 Final Exam Weeks 1 to 11
drones
- 'third generation source of remote sensing'
- agriculture, emergency services, atmospheric sciences
Big Data
refers to spatial data sets exceeding the capacity of current computing systems
Thematic maps
- a map of a theme or topic (rainfall stations, land use, geology)
Dot maps
- used to represent discrete phenomenon or themes that vary smoothly over space
- example: livestock farms, population distribution in a region
Choropleth maps
- shows regions or ranges which have the same characteristics represented with colours example:
population density
Proportional symbol map
A map that uses symbol in proportion to the value of the phenomenon it is representing.
about:blank 2/20
, 11/13/23, 1:55 AM GEOS2161 Final Exam Weeks 1 to 11
Dasymetric maps
Usually used to show population distribution using boundaries that divide the area into zones.
Isopleth maps
maps that have lines that connect points of equal intervals, often used for temperature, dew point etc
(isotherms/isobars/etc.)
three methods of division
1. equal interval
2. equal count or percentile
3. natural breaks
Equal interval method
Divides attribute values into equal size ranges. Often used to depict population on a choropleth map
density, crime rates, etc.
Equal Count or Percentile Method
data is divided percentiles, and are generally unequal
Natural Breaks Method
data is divided into classes based on natural breaks observed in data histogram
about:blank 3/20
