GRASS GIS manual: i.spectral

Note: This document is for an older version of GRASS GIS that is outdated. You should upgrade, and read the current manual page.

NAME

i.spectral - Displays spectral response at user specified locations for an imagery group or a list of raster maps.

KEYWORDS

imagery, raster, multispectral

SYNOPSIS

i.spectral
i.spectral help
i.spectral [-imc] [group=string] [raster=string[,string,...]] [output=string] [format=string] [east_north=east,north[,east,north,...]] [--overwrite] [--verbose] [--quiet]

Flags:

-i: Use a list of raster images instead of a named group
-m: Select multiple points
-c: Show pick coordinates instead of numbering in the legend
--overwrite: Allow output files to overwrite existing files
--verbose: Verbose module output
--quiet: Quiet module output

Parameters:

group=string: Imagery group name
raster=string[,string,...]: Raster input maps
output=string: Write output to image; The default is to open a new window
format=string: Graphics format for output file; Options: png,eps,svg; Default: png
east_north=east,north[,east,north,...]: Coordinates for query (non-interactive mode)

DESCRIPTION

i.spectral displays spectral response at user specified locations in images. It requires the user to either interactively select positions on the Xmonitor (the default) or can function non-interactively with sampling coordinates specified with the east_north option.

NOTES

This script needs gnuplot to be installed. Output may be to a new graphics window on your monitor (the default), or to an output file. Available output file formats are PNG, EPS, and SVG. In interactive mode use the -m flag to select multiple sampling points. Each coordinate pick will appear as a different colored line graph.

EXAMPLES

Analysis of LANDSAT TM7 channels (North Carolina dataset):

g.region rast=lsat7_2002_10 -p
d.mon x0
d.rast lsat7_2002_40
i.spectral -i rast=lsat7_2002_10,lsat7_2002_20,lsat7_2002_30,lsat7_2002_40,lsat7_2002_50,lsat7_2002_70

Spectral plot of 3 different land cover types: (1) water, (2) green vegetation, and (3) highway

To analyze a time series of maps, use:

d.rast map_1
LIST=`g.mlist type=rast mapset=timeseries pat="map_*" | \
   sort -t '_' -k 2 -n | tr '\n' ','| sed 's+,$++g'`
i.spectral -i rast=$LIST

This will search all maps in the mapset 'timeseries' which match have the 'map_' prefix and order by a number following this prefix (day of the year etc). The user is then asked to click into a map position and the resulting pixel values of all matching maps are drawn in the gnuplot output.

AUTHOR

Markus Neteler
Francesco Pirotti
Hamish Bowman

Last changed: $Date: 2013-06-28 04:57:05 -0700 (Fri, 28 Jun 2013) $

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