rastermodel

Rastermodel (often written as raster model or raster data model) is a grid-based representation of geographic phenomena. The space is divided into uniform cells (pixels) arranged in rows and columns; each cell holds a value representing an attribute of the phenomenon at that location. This contrasts with vector models that represent features as points, lines, or polygons. Raster models are widely used in geographic information systems (GIS) and remote sensing because they align well with imagery and gridded data.

A raster's essential properties include its cell size (resolution), extent, and coordinate reference system. Multi-band rasters store several values per cell, enabling concurrent measurements such as spectral bands. Data types are typically integer or floating-point; boolean rasters are used for masks or classifications. Data can be continuous (e.g., elevation, temperature) or discrete (e.g., land cover class). Common formats include GeoTIFF, ERDAS Imagine, GRID, HDF, and NetCDF, often with some compression and tiling for efficiency.

Rasters support three broad classes of operations: local (cell-by-cell), focal (neighborhood), and global (across the grid). They underpin raster algebra, terrain analysis, hydrological modeling, and image processing. Resampling and reprojection are common but can introduce artifacts when changing resolution or alignment. Memory usage is a consideration, as high-resolution rasters can be large; many systems employ tiling, pyramids, and streaming to manage data.

Limitations include lack of explicit topology, leading to challenges with network analysis; grid alignment effects can affect precision; and the need for careful handling of nodata values. Despite limitations, the raster model remains a fundamental and efficient representation for gridded geographic information and raster-based simulations.