i.tasscapgrass - Online in the Cloud

PROGRAM:

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

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