PLAN281 Lecture Notes - Lecture 8: Map Algebra, Surface 2, Noise Reduction
27 May 2016
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Document Summary
Basic display: the simplest type of values to display are integers. Each integer value can be assigned a unique colour. Legend explains the meaning of each colour. Recoding the layer before display may be required, if there are too many values for the number of categories/colours available. An informal language for manipulating representations of continuous variables defined over a common domain. Provides conventions and a syntax for how operations are combined and the order they are used (to create new raster layers) Map algebra functions can be grouped into: local or cell-based operations, focal or cell neighbourhood based operations, zonal or cell group operations, global operations. Arithmetic operations only make sense if the values have appropriate scales of measurement: e. g. : you cant find the average of soil types 3 and 5, nor is soil 5. Local operations include: reclassification/recoding, overlay, scalar. Modify cell values by a constant (e. g. : multiple cell values by.
