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41 Cards in this Set

  • Front
  • Back
attribute data types are:
-character/string/text (algoma road)
-integers (2, 250, -4)
-floating (1,333)
-dates (02/21/2002)
-time (5:00PM
Measurement scale do what?
storing techniques to ease manipulation analysis display compulation
Measurement scales include:
-nominal (named, oak, fir)
-ordinal (ordered, good, bad)
-interval (ona scale with #'s)
-Ratio (has absolute zero)
-nominal and ordinal (categorical displayed
-interval and ratio (numberical computation
The feature ID is:
each row of the feature attribute table represents a map feature and it is linked to the location and geometry of that feature by a special and unique value which is called this_____
what are raster data most suitable for?
this data type is more suitable for representation of the variation and for the processing of continuous phenomena
Examples of raster data continuous phenomena are:
rainfall distribution, vegetation, change of elevation, wind
Princile of raster data are:
1) uses a grid to represent portions of the real world
2) each cell of the grid contains a value representing the magnitude of the phenomenon to model
3) the variation of the phenomenon is expressed by the change in values of the different cells
Other names for raster data:
grid, raster map, image, surface cover
Data Representation include:
-Point (single cell)
-Line (consecutive cells)
-Area (collection of adjacent cells)
cell values are either ____ or _____
integers or floating points
integers do what:
serve to represent categorical data such as land cover
floating points do what:
are used for the representation of continuous data, such as slope
characteristics of raster data model are:
-does not clearly seperate spatial and attribute data
-has strong association b/w grid and cell values = does not make much use of DBMS
Data compression methods
MrSID is one of the most popular tools used for rater data compression compatible with ESRI products
chain coding is:
represents boundary of regions, uses cardinal directions and cell (North, East, South, West)
Block code is:
uses square blocks to represent regions
Map projecion and geometric trasnformation
just like vector data, raster data need to be projected to real world coordinate system and/or re-projected (to be display with overlapping vector data)
Rasterization is :
vector to raster conversion
Vectorizaton is :
raster to vector conversion
Data exploration is :
data query + dtat analysis
Vector data query is
done on attribue data or on spartial data
attribute data query is:
in GIS it consists of retrieving data subsets from attribute data linked to spatial data.
It requires the use of logical expressions and boolean connectors
logical expressions:
components are-
logical operators and the operands
boolean connectors are:
used to connect locial expressions in query statements
union uses:
Intersection uses:
Complement uses:
Boolena connectors :
AND, Or, not, XOR
Logical operators:
=, =<, =>, <, >, <>
Examples of operands in GIS:
field, a number, a string, date
Spatial data query:
consists of retrieving data subsets from spatial features (on a map) linked to attribute data
different ways of making feature selections:
1) selection by cursor (using mouse or cursor to point at features of interest)
2) selectoin by graphic (using graphics such as lines, circles, box polygon to reach features of interest
3) selection by spaital relationship (based on spatial relationship (based on spatial relationships of features, the spatial relationships include - containment, intersect, proximity, adjacency
Raster data query:
it is determined by the type of value stored in the cells: integer or floating-point)
recall in raster data query:
an integer grid can have an attribute table (similar to the Feature Attribut table of vector data) called the Value Attrible Table or look up table
Query by Cell Value
perfomred on grid by the use of a logical expression referring to cell values
graphic method consists of:
selecting cells with the cursor, the mouse, or a graphic object (circle, square, polygon,etc)
Network is:
layer of connected linear features
-topologically based represenation of a line layer with attributes epressing the flow of objects (car, water, train, electricicty)
characteristics of network is:
-must have attribute info. necessary for specific applications
-must have topological info
-specific network applications are not always part of basic GIS package
Overpass and underpass has two methods
1) non-planar representation= continuous lines without a node at their intersections
2) Planar representation= there are two nodes at the intersection, one of them connects the areas representing the under pass and the other one connects the areas representing the overpass, an elevation value of 1 or 0 is assigned to each node
allocation is:
the study of the spatial distribution of resources (public facilities) through a network
Location- allocation is:
matching supply and demand using objectives and constrains
- requires :
supply (service at point location) , demand (point, line or polgon) and impedance (distance measures/time)