29 terms

Resampling (GIS class)

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Georeferencing toolbar
-used to align raster data
-image moved to new location (based on control points)
Resampling required
required whenever there is a change of cell location or cell size
(between input raster and output)
projecting raster from one coordinate to another
requires resampling
resampling
filling each pixel of the new image with a value
nearest neighbor method
new pixel will be from the nearest pixel from the original image
bilinear interpolation method
average of 4 nearest pixel values
cubic convolution method
average of 16 nearest pixel values
resampling methods
-nearest neighbor
-bilinear interpolation
-cubic convolution
pyramiding
builds different pyramid levels to represent reduced or lower resolutions of larger raster
"MAKES RASTER FASTER lol"
pyramiding technique
common for displaying large raster data sets
pyramid levels
lower resolution requires less memory (level >0)
Raster analysis levels
-cell level
-group of cells
-cells within entire raster
Data analysis environment
the area of analysis and output cell size
Cell size
CAN be changed
output cell size
set equal to or larger than the largest cell size in the input raster
Analysis mask
limits analysis to cells that do not carry the cell value of "no data"
no data is not
zero
(zero is a valid cell value, no data is not)
Map algebra
rasters are manipulated using expressions to create new raster layers
map algebra example
precipitation-losses= runoff
map algebra operations
-local operations
-neighborhood operations
-zonal operations
-global operations
local operations
aka cell-by-cell operations
-creates new raster from single/multiple input rasters
-
-work on single cells
reclassification
-local operation
-creates a new raster by classification
neighborhood operations
use data from both an input location plus nearby locations to determine the output value
-
zonal operations
-work with two raster data layers
-one defines zone
-other
global functions
-output value of each cell is a function of entire grid
(useful for knowing how cells relate to each other)
typical global functions
-distance measures
-flow directions
-weighting measures
sample global operation
distance
-
-
other raster operations
-mosaic
(combines multiple input rasters into single raster)
-raster data extraction
(creates new raster from existing raster)
ERDAS
Eastern Range Dispersion Assessment System
-raster software