For example, a simple raster operation can use two or more raster layers with the same dimension sizes to produce a new raster layer by using algebraic operations (addition, subtraction, and so on), or a sophisticated raster operation to generate a Normalized Difference Vegetation Index (NDVI) from multiple bands of satellite imagery. This combination of the PL/SQL language and GeoRaster algebraic expressions and functions provides an easy-to-use, powerful way to define raster analyses as algebraic expressions, so that users can easily apply algebraic functions on raster data to derive new results. The raster algebra functions enable the usage of the expressions and support cell value-based conditional queries, mathematical modeling, classify operations, and cell value-based updates or edits over one or many raster layers from one or many GeoRaster objects.
The raster algebra expression language includes general arithmetic, casting, logical, and relational operators and allows any combination of them. GeoRaster provides a raster algebra expression language and a set of raster algebra functions for raster layer operations. PL/SQL provides declarations of variables and constants, general mathematical expressions, basic functions, statements, and programming capabilities. The GeoRaster raster algebra language is an extension to the Oracle PL/SQL language.
In GeoRaster, raster algebra is supported by the GeoRaster raster algebra language. Raster algebra is commonly used in raster data analysis and GIS modeling.
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