RASTER data Vast information

1. Seminar on
GUIDED BY
Dr. G. CHANDRAKANTH
DEPT. OF APPLIED GEOLOGY
SUBMITTED BY
NAGAMMA K.P

2. INTRODUCTION
• A representation of the world as a surface divided
into a regular grid of cells. raster models are useful
for storing data that varies continuously as in an
aerial photograph a satellite image, a surface of
chemical concentration, or an elevation surface.
• In its simplest form, a raster consists of a matrix of
cells organized into row and columns where each cell
contain a value representing information, such as
temperature. Raster are digital aerial photography,
imagery from satellite ,digital pictures, or even
scanned map.

4. ADVANTAGES OF RASTER DATA
• Simple data structures
• Overlay and combination of maps and remote
sensed images easy
• Simulation easy, because cells have the same size
and shape
• Technology is cheap
• A powerful format for advanced spatial and statistical
analysis
• The ability to represent continuous surface and
perform surface analysis.

5. •The ability to uniformly store points lines, polygons
and surface
•the inherent nature of raster maps, e.g. one attribute
maps, is ideally suited for mathematical modeling
and quantitative analysis.

6. DISADVANTAGES OF RASTER DATA
• 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.
• The cell size determines the resolution at which the
data is represented.
• It is especially difficult to adequately represent linear
features depending on the cell resolution.
accordingly, network linkages are difficult to
establish.

7. •There can be spatial inaccuracies due to the limits
imposed by the raster data set cell dimensions.
•Most output maps from grid-cell system do not
conform to high-quality cartographic needs.
•Raster database are potentially very large, Resolution
increases as the size of the cell decreases; however,
normally cost also increases in both disk space and
processing speeds, for given area, changing cells to
one-half the current size requires as much as four times
the storage space, depending on the type of data and
storage technique used.
•There is also a loss of precision that accompanies
restricting data to a regular spaced raster cell boundary.