[GRASS-SVN] r38269 - grass-addons/grass7/imagery/i.landsat.toar
svn_grass at osgeo.org
svn_grass at osgeo.org
Sun Jul 5 15:16:24 EDT 2009
Author: martinl
Date: 2009-07-05 15:16:23 -0400 (Sun, 05 Jul 2009)
New Revision: 38269
Modified:
grass-addons/grass7/imagery/i.landsat.toar/i.landsat.toar.html
Log:
manual page cleaned up
Modified: grass-addons/grass7/imagery/i.landsat.toar/i.landsat.toar.html
===================================================================
--- grass-addons/grass7/imagery/i.landsat.toar/i.landsat.toar.html 2009-07-05 19:12:27 UTC (rev 38268)
+++ grass-addons/grass7/imagery/i.landsat.toar/i.landsat.toar.html 2009-07-05 19:16:23 UTC (rev 38269)
@@ -1,135 +1,181 @@
<H2>DESCRIPTION</H2>
-<EM>i.landsat.toar</EM> is to transform calibrated digital number of Landsat products to top-of-atmosphere radiance or top-of-atmosphere reflectance and temperature (band 6 of the sensors TM and ETM+). Optionally, to calculate the at-surface radiance or reflectance with atmosferic correction (DOS method).
+<EM>i.landsat.toar</EM> is to transform calibrated digital number of
+Landsat products to top-of-atmosphere radiance or top-of-atmosphere
+reflectance and temperature (band 6 of the sensors TM and
+ETM+). Optionally, to calculate the at-surface radiance or reflectance
+with atmosferic correction (DOS method).
-<p>Usually, to do this the production date, the acquisition date, and the solar elevation is needed. Moreover, also is needed for Landsat-7 ETM+ the gain (high or low) of the nine bands.</p>
+<p>
+Usually, to do this the production date, the acquisition date, and the
+solar elevation is needed. Moreover, also is needed for Landsat-7 ETM+
+the gain (high or low) of the nine bands.
-<p>Optionally, the data can be read from header file (.met) for all Landsat MSS, TM and ETM+. However, if the solar elevation or the product creation date are given the values of metfile are overwriten. This is necessary when this data in metfile are incorrects or imprecisses.</p>
+<p>
+Optionally, the data can be read from header file (.met) for all
+Landsat MSS, TM and ETM+. However, if the solar elevation or the
+product creation date are given the values of metfile are
+overwriten. This is necessary when this data in metfile are incorrects
+or imprecisses.
-<p><b>Attention</b>: Any null value or less than QCALmin in input raster is set to null in output raster and it is not included in the equations.</p>
+<b>Attention</b>: Any null value or less than QCALmin in input raster
+is set to null in output raster and it is not included in the
+equations.
<H2>Uncorrected at-sensor values (method=uncorrected, default)</H2>
-<p>The standard geometric and radiometric correction results in a calibrated digital number (QCAL = DN) images. To further standardize the impact of illumination geometry, the QCAL images are converted first to at-sensor radiance and then to at-sensor reflectance. The thermal band is first converted from QCAL to at-sensor radiance, and then to effective at-sensor temperature in Kelvin degrees.</p>
+The standard geometric and radiometric correction results in a
+calibrated digital number (QCAL = DN) images. To further standardize
+the impact of illumination geometry, the QCAL images are converted
+first to at-sensor radiance and then to at-sensor reflectance. The
+thermal band is first converted from QCAL to at-sensor radiance, and
+then to effective at-sensor temperature in Kelvin degrees.
-<p>Radiometric calibration convert QCAL to <b>at-sensor radiance</b>, a radiometric quantity measured in W/(m²·sr·µm) with the equations:
- <ul>
+>Radiometric calibration convert QCAL to <b>at-sensor radiance</b>, a
+radiometric quantity measured in W/(m²·sr·µm) with the equations:
+
+<ul>
<li> gain = (Lmax - Lmin) / (QCALmax - QCALmin)</li>
<li> bias = Lmin - gain · QCALmin </li>
<li> radiance = gain · QCAL + bias </li>
- </ul>
+</ul>
+
where,
-<em>Lmax</em> and <em>Lmin</em> are the calibration constants, and
-<em>QCALmax</em> and <em>QCALmin</em> are the highest and the lowest points of the range of rescaled radiance in QCAL.
-</p>
-<p>Then, to calculate <b>at-sensor reflectance</b> the equations are:
- <ul>
- <li> sun_radiance = [Esun · sin(e)] / (PI · d^2)</li>
- <li> reflectance = radiance / sun_radiance </li>
- </ul>
+<em>Lmax</em> and <em>Lmin</em> are the calibration constants,
+and <em>QCALmax</em> and <em>QCALmin</em> are the highest and the
+lowest points of the range of rescaled radiance in QCAL.
+
+<p>
+Then, to calculate <b>at-sensor reflectance</b> the equations are:
+<ul>
+ <li> sun_radiance = [Esun · sin(e)] / (PI · d^2)</li>
+ <li> reflectance = radiance / sun_radiance </li>
+</ul>
+
where,
+
<em>d</em> is the earth-sun distance in astronomical units,
<em>e</em> is the solar elevation angle, and
<em>Esun</em> is the mean solar exoatmospheric irradiance in W/(m²·µm).
-</p>
<H2>Corrected at-sensor values (method=corrected)</H2>
-<p>At-sensor reflectance values range from zero to one, whereas at-sensor radiance must be greater or equal to zero. However, since Lmin can be a negative number then the at-sensor values also it can be negative. To avoid these possible negative values and set the minimum possible values at-sentor to zero, this method correct the radiance to output a corrected at-sensor values with the equations (not for thermal bands):
- <ul>
- <li> radiance = (uncorrected_radiance - Lmin) </li>
- <li> reflectance = radiance / sun_radiance </li>
- </ul>
-</p>
+At-sensor reflectance values range from zero to one, whereas at-sensor
+radiance must be greater or equal to zero. However, since Lmin can be
+a negative number then the at-sensor values also it can be
+negative. To avoid these possible negative values and set the minimum
+possible values at-sentor to zero, this method correct the radiance to
+output a corrected at-sensor values with the equations (not for
+thermal bands):
-<p><b>Note</b>: Other possibility to avoid negative values is set to zero this values (radiance and/or reflectance), but this option is ease with uncorrected method and r.mapcalc.</p>
+<ul>
+ <li> radiance = (uncorrected_radiance - Lmin) </li>
+ <li> reflectance = radiance / sun_radiance </li>
+</ul>
+<b>Note</b>: Other possibility to avoid negative values is set to zero
+this values (radiance and/or reflectance), but this option is ease
+with uncorrected method and r.mapcalc.
<H2>Simplified at-surface values (method=dos[1-4])</H2>
-<p>Atmospheric correction and reflectance calibration remove the path radiance, i.e. the stray light from the atmosphere, and the spectral effect of solar illumination. To output these simple <b>at-surface radiance</b> and <b>at-surface reflectance</b>, the equations are (not for thermal bands):
- <ul>
- <li> sun_radiance = TAUv · [Esun · sin(e) · TAUz + Esky] / (PI · d^2) </li>
- <li> radiance_path = radiance_dark - percent · sun_radiance </li>
- <li> radiance = (at-sensor_radiance - radiance_path) </li>
- <li> reflectance = radiance / sun_radiance </li>
- </ul>
+Atmospheric correction and reflectance calibration remove the path
+radiance, i.e. the stray light from the atmosphere, and the spectral
+effect of solar illumination. To output these simple <b>at-surface
+radiance</b> and <b>at-surface reflectance</b>, the equations are (not
+for thermal bands):
+
+<ul>
+ <li> sun_radiance = TAUv · [Esun · sin(e) · TAUz + Esky] / (PI · d^2) </li>
+ <li> radiance_path = radiance_dark - percent · sun_radiance </li>
+ <li> radiance = (at-sensor_radiance - radiance_path) </li>
+ <li> reflectance = radiance / sun_radiance </li>
+</ul>
+
where,
+
<em>percent</em> is a value between 0.0 and 1.0 (usually 0.01),
<em>Esky</em> is the diffuse sky irradiance,
-<em>TAUz</em> is the atmospheric transmittance along the path from the sun to the ground surface, and
-<em>TAUv</em> is the atmospheric transmittance along the path from the ground surface to the sensor.
-<em>radiance_dark</em> is the at-sensor radiance calculated from the darkest object, i.e. DN with a least 'dark_parameter' (usually 1000) pixels for the entire image.</p>
+<em>TAUz</em> is the atmospheric transmittance along the path from the
+sun to the ground surface, and
+<em>TAUv</em> is the atmospheric transmittance along the path from the
+ground surface to the sensor.
+<em>radiance_dark</em> is the at-sensor radiance calculated from the
+darkest object, i.e. DN with a least 'dark_parameter' (usually 1000)
+pixels for the entire image.</p>
The values are,
- <ul>
- <li>DOS1: TAUv = 1.0, TAUz = 1.0 and Esky = 0.0</li>
- <li>DOS2: TAUv = 1.0, Esky = 0.0, and TAUz = sin(e) for all bands with maximum wave length less than 1. (i.e. bands 4-6 MSS, 1-4 TM, and 1-4 ETM+) other bands TAUz = 1.0</li>
- <li>DOS3: TAUv = exp[-t/cos(sat_zenith)], TAUz = exp[-t/sin(e)], Esky = rayleigh</li>
- <li>DOS4: TAUv = exp[-t/cos(sat_zenith)], TAUz = exp[-t/sin(e)], Esky = PI · radiance_dark </li>
- </ul>
-<p><b>Attention</b>: Output radiance remain untouched (i.e. no set to 0. when it is negative) then they are possible negative values. However, output reflectance is set to 0. when is obtained a negative value.</p>
+<ul>
+ <li>DOS1: TAUv = 1.0, TAUz = 1.0 and Esky = 0.0</li>
+ <li>DOS2: TAUv = 1.0, Esky = 0.0, and TAUz = sin(e) for all bands with maximum wave length less than 1. (i.e. bands 4-6 MSS, 1-4 TM, and 1-4 ETM+) other bands TAUz = 1.0</li>
+ <li>DOS3: TAUv = exp[-t/cos(sat_zenith)], TAUz = exp[-t/sin(e)], Esky = rayleigh</li>
+ <li>DOS4: TAUv = exp[-t/cos(sat_zenith)], TAUz = exp[-t/sin(e)], Esky = PI · radiance_dark </li>
+</ul>
+<b>Attention</b>: Output radiance remain untouched (i.e. no set to
+0. when it is negative) then they are possible negative
+values. However, output reflectance is set to 0. when is obtained a
+negative value.
<H2>NOTES</H2>
-<p>In verbose mode (flag -v), the program write basic data of satellite and the parameters used in
-transformations.</p>
+In verbose mode (flag -v), the program write basic data of satellite
+and the parameters used in transformations.
-<p>Production date is not a exact value and it is necessary to apply correct calibration constants, which were changed in the dates:
- <ul>
- <li>Landsat-1 MSS: never </li>
- <li>Landsat-2 MSS: July 16, 1975</li>
- <li>Landsat-3 MSS: June 1, 1978</li>
- <li>Landsat-4 MSS: August 26, 1982 and April 1, 1983</li>
- <li>Landsat-4 TM: August 1, 1983 and January 15, 1984</li>
- <li>Landsat-5 MSS: April 6, 1984 and November 9, 1984</li>
- <li>Landsat-5 TM: May 4, 2003 and April, 2 2007</li>
- <li>Landsat-7 ETM+: July 1, 2000</li>
- </ul>
-</p>
+Production date is not a exact value and it is necessary to apply
+correct calibration constants, which were changed in the dates:
+<ul>
+ <li>Landsat-1 MSS: never </li>
+ <li>Landsat-2 MSS: July 16, 1975</li>
+ <li>Landsat-3 MSS: June 1, 1978</li>
+ <li>Landsat-4 MSS: August 26, 1982 and April 1, 1983</li>
+ <li>Landsat-4 TM: August 1, 1983 and January 15, 1984</li>
+ <li>Landsat-5 MSS: April 6, 1984 and November 9, 1984</li>
+ <li>Landsat-5 TM: May 4, 2003 and April, 2 2007</li>
+ <li>Landsat-7 ETM+: July 1, 2000</li>
+</ul>
+
<H2>EXAMPLES</H2>
-<p>Transform digital numbers of Landsat-7 ETM+ in band rasters 203_30.1, 203_30.2
-[...] to uncorrected at-sensor reflectance in output files 203_30.toar.1,
-203_30.toar.2 [...] and at-sensor temperature in output files 293_39.toar.61 and 293_39.toar.62:</p>
+Transform digital numbers of Landsat-7 ETM+ in band rasters 203_30.1,
+203_30.2 [...] to uncorrected at-sensor reflectance in output files
+203_30.toar.1, 203_30.toar.2 [...] and at-sensor temperature in output
+files 293_39.toar.61 and 293_39.toar.62:
<div class="code"><pre>
i.landsat.toar -7 band=203_30 met=p203r030_7x20010620.met
</pre></div>
-<p>or</p>
+or
<div class="code"><pre>
i.landsat.toar -7 band=203_30 product=2004-06-07 date=2001-06-20 solar=64.3242970 gain="HHHLHLHHL"
</pre></div>
<H2>REFERENCES</H2>
+
<ol>
- <li>Chander G.H. and B. Markham: IEEE Transactions On Geoscience And Remote Sensing, vol. 41, no. 11, November 2003.</li>
- <li>Chavez P.S., jr. 1996. Image-based atmospheric corrections - Revisited and Improved. Photogrammetric Engineering and Remote Sensing 62 (9): 1025-1036.</li>
- <li>Huang et al: At-Satellite Reflectance: A First Order Normalization Of Landsat 7 ETM+ Images. 2002.</li>
- <li>R. Irish: <a href="http://ltpwww.gsfc.nasa.gov/IAS/handbook/handbook_toc.html">Landsat 7. Science Data Users Handbook. February 17, 2007.</a></li>
- <li>Markham B.L. and J.L. Barker: Landsat MSS and TM Post-Calibration Dynamic Ranges, Exoatmospheric Reflectances and At-Satellite Temperatures. EOSAT Landsat Technical Notes, No. 1, 1986</li>
- <li>Moran M.S., R.D. Jackson, P.N. Slater and P.M. Teillet: Remote Sensing of Environment, vol. 41. 1992.</li>
- <li> Song et al : Classification and Change Detection Using Landsat TM Data: When and How to Correct Atmospheric Effects?. Remote Sensing of Environment, vol. 75. 2001. </li>
-
+ <li>Chander G.H. and B. Markham: IEEE Transactions On Geoscience And Remote Sensing, vol. 41, no. 11, November 2003.</li>
+ <li>Chavez P.S., jr. 1996. Image-based atmospheric corrections - Revisited and Improved. Photogrammetric Engineering and Remote Sensing 62 (9): 1025-1036.</li>
+ <li>Huang et al: At-Satellite Reflectance: A First Order Normalization Of Landsat 7 ETM+ Images. 2002.</li>
+ <li>R. Irish: <a href="http://ltpwww.gsfc.nasa.gov/IAS/handbook/handbook_toc.html">Landsat 7. Science Data Users Handbook. February 17, 2007.</a></li>
+ <li>Markham B.L. and J.L. Barker: Landsat MSS and TM Post-Calibration Dynamic Ranges, Exoatmospheric Reflectances and At-Satellite Temperatures. EOSAT Landsat Technical Notes, No. 1, 1986</li>
+ <li>Moran M.S., R.D. Jackson, P.N. Slater and P.M. Teillet: Remote Sensing of Environment, vol. 41. 1992.</li>
+ <li> Song et al : Classification and Change Detection Using Landsat TM Data: When and How to Correct Atmospheric Effects?. Remote Sensing of Environment, vol. 75. 2001. </li>
</ol>
-
<H2>SEE ALSO</H2>
<em>
-<A HREF="r.mapcalc.html">r.mapcalc</A><br>
-<A HREF="r.in.gdal.html">r.in.gdal</A><br>
+ <A HREF="r.mapcalc.html">r.mapcalc</A><br>
+ <A HREF="r.in.gdal.html">r.in.gdal</A><br>
</em>
-
<H2>AUTHOR</H2>
E. Jorge Tizado (ej.tizado unileon es)<br>
More information about the grass-commit
mailing list