### imagery (1)

#### GRASS GIS 7.2.1 Reference Manual

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 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 calcula-

tion.

i.cca Canonical components analysis (CCA) program for image pro-

cessing.

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.rectify Orthorectifies an image by using the image to photo coordi-

nate transformation matrix.

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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2003-2017 GRASS Development Team, GRASS GIS 7.2.1 Reference Manual