DATA MANAGEMENT:
SPATIAL COMPONENT
RASTER AND VECTOR FORMATS
RASTER :
Grid-based, Simplify reality
VECTOR :
Analog map, Cartography
DATA MODEL OF RASTER AND VECTOR
REAL WORLD
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GRID RASTER
VECTOR
RASTER DATA MODEL
• derive from formulation that real world has spatial
elements and objects fills those elements
• real world is represented with uniform cells
• list of cells is a rectangle
• cell comprises of triangles, hexagon and higher
complexities
• a cell reports its own true characteristics
• per units cell does not represent an object
• an object is represented by a group of cells
Lake
Pond
Reality - Hydrography
Lake
Pond
Reality overlaid with a grid
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0 0 0 0 2 2 0 0 0 0 0 0
0 = No Water Feature
1 = Water Body
2 = River
0 0 0 2 0 0 0 0 0 0 0 0
Resulting raster
Creating a Raster
VECTOR DATA MODEL
• derived from the formulation of spatial concepts that
emphasize on real world objects
• geometry primitives of vector data model are point,
line and polygon
– objects can be built from these primitives
• object location determined by represented location
point
• uniqueness of vector data model lies in its
management and storage of data geometry primitives
– spaghetti model
– topology model
VECTOR CHARACTERICTIS
POINT
LINE
POLYGON
X
RASTER TO VECTOR
RIVER CHANGED FROM RASTER TO VECTOR FORMAT
RIVER THAT HAS BEEN VECTORISED
ORIGINAL RIVER
PRO AND CONS OF RASTER MODEL
• pro
– raster data is more affordable
– simple data structure
– very efficient overlay operation
• cons
– topology relationship difficult to implement
– raster data requires large storage
– not all world fenomena related directly with raster
representation
– raster data mainly is obtained from satellite
images and scanning
PRO AND CONS OF VECTOR MODEL
• pro
– more efficient data storage
– topological encoding more efferent
– suitable for most usage and compatible with data
– good graphic presentation
• cons
– overlay operation not efficient
– complex data structure