8 - Geographic data processing—raster data

Abstract

Raster geographic information system (GIS) databases provide an efficient and effective way to visualize broad, complete landscapes or water bodies that originate from converted, scanned, or remotely sensed data. They vary in scope from raw satellite and aerial imagery data to land cover classifications, elevation databases, environmental data (e.g., precipitation), and others. Raster GIS databases may be used indirectly to facilitate vector digitizing efforts, or more directly to extract through mathematical classification processes those features of a landscape or water body of interest to land managers. Raster GIS databases can be converted to other data types, including vector GIS databases, through processes that generalize spatial relationships based on the values contained within each grid cell. Raster GIS databases can also be combined and mathematically manipulated (through map algebra) to determine various values (average, difference, etc.) of land resources or phenomena. For example, elevation data associated with grid cells in a raster GIS database can be mathematically manipulated to create slope and aspect GIS databases, which may be important for informing logging and planting operations. Knowledge of the capabilities of raster GIS databases may allow natural resources managers to not only visualize a broader landscape beyond the land they manage but also help them make timely, effective management decisions.