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1
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2
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3
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- GIS is:
- A mapping software – such as Electronic Atlas:
- It displays pictures of geographic areas on the computer
- It provides information about these areas
- It provides ability to alter graphics
- And even more than that, it has the ability:
- To create graphics using information database
- To import external information & databases
- To use tabular information to create charts & graphs
- And to analyze information statistically
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4
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5
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- Hardware: the computer on which GIS operates
- Software: which provides the
- functions and tools needed to store,
- analyze, and display geographic
- information.
- Data: geographic data & related
- tabular data
- People: GIS users who range from
- specialists to simple users
- Methods: a designed plan and business rules
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6
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- GIS works with two models:
- Vector: information is encoded
- and stored as a collection of
- x,y coordinates
- Raster: comprises a collection
- of grid cells
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7
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- GIS stores information about the world as a collection of thematic
layers that can be linked together by geography
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8
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- Every object is called Map Feature…
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9
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10
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- Map features are represented as points, lines or areas…
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11
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- GIS stores all descriptive information about features as attributes in a
GIS database.
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12
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- Any change in the attribute table is reflected on the map.
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13
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14
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- Sets of features and attributes together are called themes:
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15
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- All themes together make the GIS database
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16
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- Map scale controls the size of features and shapes used to represent
them, i.e. when map scale increases, so does the size of the map
feature.
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17
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- With GIS we can:
- Get information about features
- Find features based on their attributes
- Analyze features locations
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18
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- Here we are seeking to find out what exists at a particular location.
- A location can be described in
many different ways using, for example, place name, or latitude and
longitude coordinates
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19
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20
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- Getting other types of information about a feature
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21
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- Instead of identifying what exists at a given location, you want to
find a location where certain conditions are satisfied.
- For example, you wish to find a house assessed at less than $200,000
with 4 bedrooms and made of wood.
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22
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- Find features based on attributes they share
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23
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24
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25
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26
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27
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- GIS locates features with regards to their location to each other:
- Features adjacent to…
- Features within a certain distance
- Features within a certain area
- Etc…
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28
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- Looking for an apartment within 0.5 km from high school
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29
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- vehicle routing and scheduling
- location analysis, site selection
- development of evacuation plans
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30
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31
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32
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Notes
