geoprimsField-grade geospatial math

Raster

Elevation and terrain from grids.

Not yet independently reviewed by a GIS professional.

Raster tools work on the numbers in one pixel or a small window of a satellite image or elevation model: scaling bands to reflectance, spectral indices such as NDVI, and terrain measures such as slope and ruggedness. They are for checking a formula or a pixel by hand, not for processing whole scenes. Start by scaling a band to reflectance, then compute an index from it. All of the raster tools are still experimental.

Index

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Spectral indices from surface reflectance: vegetation, water, built-up, and burn severity, each with the paper it comes from.

Scale

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Turning a band's stored digital numbers into surface reflectance, with each sensor's own scaling.

Terrain

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What a digital elevation model says about a cell: how steep it is, which way it faces, and how broken the ground around it is.