GRASS GIS 7.8.6 Reference Manual

Geographic Resources Analysis Support System, commonly referred to as GRASS GIS, is a Geographic Information System (GIS) used for geospatial data management and analysis, image processing, graphics/maps production, spatial modeling, and visualization. GRASS is currently used in academic and commercial settings around the world, as well as by many governmental agencies and environmental consulting companies.

This reference manual details the use of modules distributed with Geographic Resources Analysis Support System (GRASS), an open source (GNU GPLed), image processing and geographic information system (GIS). Go to imagery introduction | topics

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Imagery commands:

i.albedo		Computes broad band albedo from surface reflectance.
i.aster.toar		Calculates Top of Atmosphere Radiance/Reflectance/Brightness Temperature from ASTER DN.
i.atcorr		Performs atmospheric correction using the 6S algorithm.
i.biomass		Computes biomass growth, precursor of crop yield calculation.
i.cca		Canonical components analysis (CCA) program for image processing.
i.cluster		Generates spectral signatures for land cover types in an image using a clustering algorithm.
i.colors.enhance		Performs auto-balancing of colors for RGB images.
i.eb.eta		Actual evapotranspiration for diurnal period (Bastiaanssen, 1995).
i.eb.evapfr		Computes evaporative fraction and root zone soil moisture.
i.eb.hsebal01		Computes sensible heat flux iteration SEBAL 01.
i.eb.netrad		Net radiation approximation (Bastiaanssen, 1995).
i.eb.soilheatflux		Soil heat flux approximation (Bastiaanssen, 1995).
i.emissivity		Computes emissivity from NDVI, generic method for sparse land.
i.evapo.mh		Computes evapotranspiration calculation modified or original Hargreaves formulation, 2001.
i.evapo.pm		Computes potential evapotranspiration calculation with hourly Penman-Monteith.
i.evapo.pt		Computes evapotranspiration calculation Priestley and Taylor formulation, 1972.
i.evapo.time		Computes temporal integration of satellite ET actual (ETa) following the daily ET reference (ETo) from meteorological station(s).
i.fft		Fast Fourier Transform (FFT) for image processing.
i.gensig		Generates statistics for i.maxlik from raster map.
i.gensigset		Generates statistics for i.smap from raster map.
i.group		Creates, edits, and lists groups of imagery data.
i.his.rgb		Transforms raster maps from HIS (Hue-Intensity-Saturation) color space to RGB (Red-Green-Blue) color space.
i.ifft		Inverse Fast Fourier Transform (IFFT) for image processing.
i.image.mosaic		Mosaics several images and extends colormap.
i.in.spotvgt		Imports SPOT VGT NDVI data into a raster map.
i.landsat.acca		Performs Landsat TM/ETM+ Automatic Cloud Cover Assessment (ACCA).
i.landsat.toar		Calculates top-of-atmosphere radiance or reflectance and temperature for Landsat MSS/TM/ETM+/OLI
i.maxlik		Classifies the cell spectral reflectances in imagery data.
i.modis.qc		Extracts quality control parameters from MODIS QC layers.
i.oif		Calculates Optimum-Index-Factor table for spectral bands
i.ortho.camera		Select and modify the imagery group camera reference file.
i.ortho.elev		Select or modify the target elevation model.
i.ortho.init		Interactively creates or modifies entries in a camera initial exposure station file for imagery group referenced by a sub-block.
i.ortho.photo		Menu driver for the photo imagery programs.
i.ortho.rectify		Orthorectifies an image by using the image to photo coordinate transformation matrix.
i.ortho.target		Select or modify the imagery group target.
i.ortho.transform		Computes a coordinate transformation based on the control points.
i.pansharpen		Image fusion algorithms to sharpen multispectral with high-res panchromatic channels
i.pca		Principal components analysis (PCA) for image processing.
i.rectify		Rectifies an image by computing a coordinate transformation for each pixel in the image based on the control points.
i.rgb.his		Transforms raster maps from RGB (Red-Green-Blue) color space to HIS (Hue-Intensity-Saturation) color space.
i.segment		Identifies segments (objects) from imagery data.
i.smap		Performs contextual image classification using sequential maximum a posteriori (SMAP) estimation.
i.spectral		Displays spectral response at user specified locations in group or images.
i.target		Targets an imagery group to a GRASS location and mapset.
i.tasscap		Performs Tasseled Cap (Kauth Thomas) transformation.
i.topo.corr		Computes topographic correction of reflectance.
i.vi		Calculates different types of vegetation indices.
i.zc		Zero-crossing "edge detection" raster function for image processing.

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