NAME

       i.tasscap  - Performs Tasseled Cap (Kauth Thomas) transformation.

KEYWORDS

       imagery, transformation, Landsat, MODIS, Tasseled Cap transformation

SYNOPSIS

       i.tasscap
       i.tasscap --help
       i.tasscap  input=name[,name,...]  output=basename  sensor=string   [--overwrite]  [--help]
       [--verbose]  [--quiet]  [--ui]

   Flags:
       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       input=name[,name,...] [required]
           For Landsat4-7: bands 1, 2, 3, 4, 5, 7; for Landsat8: bands 2, 3,  4,  5,  6,  7;  for
           MODIS: bands 1, 2, 3, 4, 5, 6, 7

       output=basename [required]
           Name for output basename raster map(s)
           Name for output basename raster map(s)

       sensor=string [required]
           Satellite sensor
           Options: landsat4_tm, landsat5_tm, landsat7_etm, landsat8_oli, modis
           landsat4_tm: Use transformation rules for Landsat 4 TM
           landsat5_tm: Use transformation rules for Landsat 5 TM
           landsat7_etm: Use transformation rules for Landsat 7 ETM
           landsat8_oli: Use transformation rules for Landsat 8 OLI
           modis: Use transformation rules for MODIS

DESCRIPTION

       i.tasscap  calculates  Tasseled  Cap (Kauth Thomas, TC) transformation for Landsat TM data
       (TM4, TM5, ETM7) and MODIS  data.   The  tasseled  cap  transformation  is  effectively  a
       compression  method  to  reduce  multiple  spectral  data into a few bands. The method was
       originally developed for understanding important phenomena of crop development in spectral
       space (Kauth and Thomas 1976).

       Tasseled cap coefficients for Landsat 7 ETM+ are at-satellite reflectance values (C. Huang
       et al., 2001), the conversion can be achieved with i.landsat.toar.

       The following TC components are generated:

           •   tasscap.1: corresponds to brightness,

           •   tasscap.2: corresponds to greenness,

           •   tasscap.3: corresponds to wetness,

           •   tasscap.4: corresponds to atmospheric haze (only selected sensors: Landsat 5,7,8).

EXAMPLE

       Calculation of TC maps from North Carolina Landsat 7 ETM scene:
       g.region raster=lsat7_2002_10 -p
       i.tasscap sensor=landsat7_etm \
         input=lsat7_2002_10,lsat7_2002_20,lsat7_2002_30,lsat7_2002_40,lsat7_2002_50,lsat7_2002_70 \
         output=tasscap
       Results:

       ’Brightness’ Tasseled Cap component 1                        ’Greenness’ Tasseled Cap component 2

       ’Wetness’ Tasseled Cap component 3                           ’Atmospheric haze’ Tasseled Cap component 4

REFERENCES

           •   LANDSAT-4/LANDSAT-5: TC-factor changed to CRIST et al. 1986,  Proc.  IGARSS  1986,
               p.1467

           •   Crist,  E.  P.,  1985, A TM tasseled cap equivalent transformation for reflectance
               factor data, Remote Sensing of Environment, 17: 301-306.

           •   LANDSAT-7: TASSCAP factors cited from: DERIVATION OF A TASSELED CAP TRANSFORMATION
               BASED  ON LANDSAT 7 AT-SATELLITE REFLECTANCE.  Chengquan Huang, Bruce Wylie, Limin
               Yang, Collin Homer and Gregory Zylstra Raytheon ITSS, USGS EROS Data Center  Sioux
               Falls, SD 57198, USA http://landcover.usgs.gov/pdf/tasseled.pdf
               This is published as well in INT. J. OF RS, 2002, VOL 23, NO. 8, 1741-1748.

           •   MODIS  Tasselled  Cap  coefficients  - Ref: Lobser & Cohen (2007). MODIS tasselled
               cap:  land  cover  characteristics  expressed  through  transformed  MODIS   data.
               International Journal of Remote Sensing, Volume 28(22), Table 3

SEE ALSO

        i.albedo, i.aster.toar, i.landsat.toar, i.atcorr, i.vi

AUTHOR

       Markus Neteler, ITC-irst, based on a script by Agustin Lobo

       Last changed: $Date: 2014-12-19 22:55:37 +0100 (Fri, 19 Dec 2014) $

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