GRASS GIS 6.2.4cvs 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 GPL'ed), image processing and geographic information system (GIS).

Quick Introduction

imagery commands:
i.cca Canonical components analysis (cca) program for image processing.
i.class i.class
i.cluster An imagery function that generates spectral signatures for land cover types in an image using a clustering algorithm. The resulting signature file is used as input for i.maxlik, to generate an unsupervised image classification.
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 layer.
i.gensigset Generate statistics for i.smap from raster map layer. Creates and edits groups and subgroups of imagery files.
i.his.rgb Hue-intensity-saturation (his) to red-green-blue (rgb) raster map color transformation function.
i.ifft Inverse Fast Fourier Transform (ifft) for image processing.
i.image.mosaic Mosaics up to 4 images and extends colormap; creates map *.mosaic Import of SPOT VGT NDVI file into a raster map
i.landsat.rgb Auto-balancing of colors for LANDSAT images
i.maxlik An imagery function that classifies the cell spectral reflectances in imagery data based on the spectral signature information generated by either i.cluster, i.class, or i.gensig.
i.oif Calculates Optimum-Index-Factor table for LANDSAT TM bands 1-5, & 7
i.pca Principal components analysis (pca) program for image processing.
i.points Mark ground control points on image to be rectified.
i.rectify Rectifies an image by computing a coordinate transformation for each pixel in the image based on the control points
i.rgb.his Red-green-blue (rgb) to hue-intensity-saturation (his) raster map color transformation function.
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 Targets an imagery group to a GRASS location and mapset.
i.tasscap Tasseled Cap (Kauth Thomas) transformation for LANDSAT-TM data
i.vpoints Set registration points for an imagery group from a vector map or keyboard entry.
i.zc Zero-crossing "edge detection" raster function for image processing.

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