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Raster Vs Vector Data

Raster Vs Vector Data 


Basic Elements:

  1. Location (x,y) or (x,y,z)

  2. Explicit, i.e. pegged to a coordinate system

  3. Different coordinate system (and precision) require different values:

    •   e.g. UTM as integer (but large)

    •   Lat, long as two floating point numbers +/-

  4.  Points are used to build more complex features

  • Advantages of Vector Data Structures:
    • Good representation of phenomenonology
    • Compact
    • Topology can be completely described
    • Accurate graphics
    • Retrieval, updating and generalization of graphics and attributes possible

    Disadvantages of Vector Data Structures:
    • Complex Data Structures
    • Combination of several vector polygon maps through overlay creates difficulties
    • Simulation is difficult because each unit has a different topological form
    • Display and plotting can be expensive, particularly for high quality color
    • The technology is expensive, particularly for the more sophisticated software and hardware
    • Spatial analysis and filtering within polygons are impossible 


    1. Shapefile
                o Point, or multi-point
                o Line, or polyline
                o Polygon  

    2. Coverage
               o Point, or node                                      
               o Arc, or line
               o Polygon
               o Label


    Administrative borders
Linear features
Discrete habitat boundaries


Basic Elements

  1. Extent

    •     Rows

    •    Columns 

  2.  Origin 

  3. Orientation

  4. Resolution: pixel = grain = grid cell 
  5. Advantages of Raster Data Structures:

    • Simple data structures
    • Overlay and combination of maps and remote sensed images easy
    • Some spatial analysis methods simple to perform
    • Simulation easy, because cells have the same size and shape
    • Technology is cheap 
  6. Disadvantages of Raster Data Structures:

    • The use of large cells to reduce data volumes means that phenomenonologically recognizable structures can be lost and there can be a serious loss of information
    • Crude raster maps are considerably less beautiful than line maps
    • Network linkages are difficult to establish
    • Projection transformations are time consuming unless special algorithms or hardware is used.
  •   Temperature (air, water)
  •  Air pressure
  •  Ecotones
  •  Soil ph
  •  Precipitation
  •  Salinity
  •  Elevation & its derivatives
  •  Flow
  •  Direction, distance
  •  Reflectance (photography/imagery) 

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