Geographic Resources Analysis Support System, commonly referred to as GRASS, 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 back to help overview| 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.eb.eta | actual evapotranspiration for diurnal period (Bastiaanssen, 1995) |
| i.eb.evapfr | Computes evaporative fraction (Bastiaanssen, 1995) and root zone soil moisture (Makin, Molden and Bastiaanssen, 2001) |
| i.eb.h_SEBAL01 | |
| 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 spares land. |
| i.evapo.mh | Computes evapotranspiration calculation modified or original Hargreaves formulation, 2001. |
| i.evapo.pm | Computes potontial evapotranspiration calculation with hourly Penman-Monteith. |
| i.evapo.pt | Computes evapotranspiration calculation Prestley 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.fusion.brovey | Brovey transform to merge multispectral and high-res panchromatic channels |
| 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 and subgroups of imagery files. |
| 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 | Landsat TM/ETM+ Automatic Cloud Cover Assessment (ACCA). |
| i.landsat.rgb | Performs auto-balancing of colors for LANDSAT images. |
| i.landsat.toar | Calculates top-of-atmosphere radiance or reflectance and temperature for Landsat MSS/TM/ETM+. |
| i.latlong | creates a latitude/longitude map |
| i.maxlik | Classifies the cell spectral reflectances in imagery data. |
| i.modis.qc | Extract quality control parameters from Modis QC layers |
| i.oif | Calculates Optimum-Index-Factor table for LANDSAT TM bands 1-5, & 7 |
| 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.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.sunhours | creates a sunshine hours map |
| i.target | Targets an imagery group to a GRASS location and mapset. |
| i.tasscap | Tasseled Cap (Kauth Thomas) transformation for LANDSAT-TM data |
| i.vi | Calculates different types of vegetation indices. |
| i.zc | Zero-crossing "edge detection" raster function for image processing. |
Help Index | Full Index
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