DATA MANAGEMENT SPATIAL COMPONENT RASTER AND VECTOR FORMATS
- Slides: 10
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 1 2 3 4 5 6 7 8 9 10 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 r ve Ri Pond Reality - Hydrography Lake r ve Ri Pond Reality overlaid with a grid 0 0 0 0 0 1 0 0 0 0 0 2 0 0 0 0 2 0 0 0 1 2 0 0 1 1 0 0 0 1 1 1 0 0 0 0 0 = No Water Feature 1 = Water Body 2 = River 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
