Raster data structures

Grid Cell/Square based Raster Data Model • Dividing space into discrete uniform units-square cells, namely a cellular model of geometry. • The squares have valuable conditions: equality of sides, decomposability, stability for orientation and aggregation. Therefore, squares dominate the regular tessellations for representing spatial information. • Location is inherent in the storage structure, namely, implied by row and column number of the grid cell rather than through the use of explicit spatial coordinates. Raster data structure does not provide precise locational information. • Two-dimensional array of grid cells is called a layer, a grid, or an image in different contexts. Each layer of raster data is often used to represent a particular topic (theme). • Various thematic layers can be organized as a stack to describe a geographic area. Multi-layers in a GIS database, Multi-spectral, multi-band data in image analysis.