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<h2>DESCRIPTION</h2>
<em>i.tasscap</em> calculates Tasseled Cap (Kauth Thomas, TC) transformation
for Landsat TM data (TM4, TM5, ETM7), MODIS and Sentinel-2 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).
<p>
Tasseled cap coefficients for Landsat 7 ETM+ are at-satellite reflectance
values (C. Huang et al., 2001), the conversion can be achieved with
<em>i.landsat.toar</em>.
<p>
The following tasseled cap components are generated:
<ul>
<li> tasscap.1: corresponds to brightness,</li>
<li> tasscap.2: corresponds to greenness,</li>
<li> tasscap.3: corresponds to wetness,</li>
<li> tasscap.4: corresponds to atmospheric haze (only selected sensors: Landsat 5,7,8).</li>
</ul>
<h2>EXAMPLE</h2>
Calculation of TC maps from North Carolina Landsat 7 ETM scene:
<div class="code"><pre>
# See manual page of i.landsat.toar for pre-processing
g.region raster=lsat7_2002_toar.1 -p
i.tasscap sensor=landsat7_etm \
input=lsat7_2002_toar.1,lsat7_2002_toar.2,lsat7_2002_toar.3,lsat7_2002_toar.4,lsat7_2002_toar.5,lsat7_2002_toar.7 \
output=lsat7_2002_tasscap
</pre></div>
Results:
<p>
<center>
<table border="1">
<tr>
<td align=center>
<img src="i_tasscap_brightness.jpg" alt="'Brightness' Tasseled Cap component 1">
<br>
<font size="-1">
<i>'Brightness' Tasseled Cap component 1</i>
</font>
</td>
<td align=center>
<img src="i_tasscap_greenness.jpg" alt="'Greenness' Tasseled Cap component 2">
<br>
<font size="-1">
<i>'Greenness' Tasseled Cap component 2</i>
</font>
</td>
</tr>
<tr>
<td align=center>
<img src="i_tasscap_wetness.jpg" alt="'Wetness' Tasseled Cap component 3">
<br>
<font size="-1">
<i>'Wetness' Tasseled Cap component 3</i>
</font>
</td>
<td align=center>
<img src="i_tasscap_haze.jpg" alt="'Atmospheric haze' Tasseled Cap component 4">
<br>
<font size="-1">
<i>'Atmospheric haze' Tasseled Cap component 4</i>
</font>
</td>
</tr>
</table>
</center>
<br>
<h2>REFERENCES</h2>
<ul>
<li>LANDSAT-4/LANDSAT-5: TC-factor changed to CRIST et al. 1986,
Proc. IGARSS 1986, p.1467</li>
<li>Crist, E. P., 1985, A TM tasseled cap equivalent transformation for reflectance
factor data, Remote Sensing of Environment, 17: 301-306.</li>
<li>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
(<a href="https://digitalcommons.unl.edu/usgsstaffpub/621/">PDF</a>).
This is published as well in INT. J. OF RS, 2002, VOL 23, NO. 8, 1741-1748.</li>
<li> MODIS Tasseled Cap coefficients - Ref: Lobser & Cohen (2007). MODIS tasseled cap:
land cover characteristics expressed through transformed MODIS data.
International Journal of Remote Sensing, Volume 28(22), Table 3</li>
<li> Sentinel-2 Tasseled Cap coefficients - Ref: Nedkov, R. (2017). Orthogonal transformation
of segmented images from the satellite Sentinel-2.
Comptes rendus de l'Académie bulgare des sciences, 70:687-692.</li>
<li>Yarbrough, L., Navulur, R., 2014, Presentation of the Kauth-Thomas transform
for WorldView-2 reflectance data. Remote Sensing Letters. 5. DOI: 10.1080/2150704X.2014.885148.</li>
</ul>
<h2>SEE ALSO</h2>
<em>
<a href="i.albedo.html">i.albedo</a>,
<a href="i.atcorr.html">i.atcorr</a>,
<a href="i.landsat.toar.html">i.landsat.toar</a>,
<a href="i.vi.html">i.vi</a>
</em>
<h2>AUTHORS</h2>
Dr. Agustin Lobo, original script, 1997
<p>
Markus Neteler, ITC-irst, 2001
<p>
Converted to Python by Glynn Clements
<p>
Code improvements by Leonardo Perathoner
<p>
Sentinel-2 support by Veronica Andreo
<p>
Worldview-2 support by Markus Neteler
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