[GRASS-SVN] r43441 - grass-addons/imagery/i.landsat.toar
svn_grass at osgeo.org
svn_grass at osgeo.org
Thu Sep 9 19:43:18 EDT 2010
Author: hamish
Date: 2010-09-09 23:43:18 +0000 (Thu, 09 Sep 2010)
New Revision: 43441
Modified:
grass-addons/imagery/i.landsat.toar/description.html
Log:
linewrap
Modified: grass-addons/imagery/i.landsat.toar/description.html
===================================================================
--- grass-addons/imagery/i.landsat.toar/description.html 2010-09-09 13:36:35 UTC (rev 43440)
+++ grass-addons/imagery/i.landsat.toar/description.html 2010-09-09 23:43:18 UTC (rev 43441)
@@ -1,19 +1,37 @@
<H2>DESCRIPTION</H2>
-<EM>i.landsat.toar</EM> is used to transform the calibrated digital number of Landsat imagery products to top-of-atmosphere radiance or top-of-atmosphere reflectance and temperature (band 6 of the sensors TM and ETM+). Optionally, it can be used to calculate the at-surface radiance or reflectance with atmosferic correction (DOS method).
+<EM>i.landsat.toar</EM> is used to transform the calibrated digital number
+of Landsat imagery products to top-of-atmosphere radiance or
+top-of-atmosphere reflectance and temperature (band 6 of the sensors TM and
+ETM+). Optionally, it can be used to calculate the at-surface radiance or
+reflectance with atmosferic correction (DOS method).
-<p>Usually, to do so the production date, the acquisition date, and the solar elevation is needed. Moreover, for Landsat-7 ETM+ it is also needed the gain (high or low) of the nine respective bands.</p>
+<p> Usually, to do so the production date, the acquisition date, and the
+solar elevation is needed. Moreover, for Landsat-7 ETM+ it is also needed
+the gain (high or low) of the nine respective bands.</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 the metfile are overwriten. This is necessary when the data in the metfile is incorrect or not accurate.</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 the metfile are overwriten. This is
+necessary when the data in the metfile is incorrect or not accurate.</p>
-<p><b>Attention</b>: Any null value or smaller than QCALmin in the input raster is set to null in the output raster and it is not included in the equations.</p>
+<p> <b>Attention</b>: Any null value or smaller than QCALmin in the input
+raster is set to null in the output raster and it is not included in the
+equations.</p>
<H2>Uncorrected at-sensor values (method=uncorrected, default)</H2>
-<p>The standard geometric and radiometric corrections result in a calibrated digital number (QCAL = DN) images. To further standardize the impact of illumination geometry, the QCAL images are first 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>
+<p> The standard geometric and radiometric corrections result in a
+calibrated digital number (QCAL = DN) images. To further standardize the
+impact of illumination geometry, the QCAL images are first 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>
-<p>Radiometric calibration converts QCAL to <b>at-sensor radiance</b>, a radiometric quantity measured in W/(m²·sr·µm) using the equations:
+<p>
+Radiometric calibration converts QCAL to <b>at-sensor radiance</b>, a
+radiometric quantity measured in W/(m²·sr·µm) using the equations:
<ul>
<li> gain = (Lmax - Lmin) / (QCALmax - QCALmin)</li>
<li> bias = Lmin - gain · QCALmin </li>
@@ -21,10 +39,12 @@
</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.
+<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:
+<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>
@@ -38,19 +58,33 @@
<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 can also be negative. To avoid these possible negative values and set the minimum possible values at-sensor to zero, this method corrects the radiance to output a corrected at-sensor values using the equations (not for thermal bands):
+<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 can also be negative. To avoid
+these possible negative values and set the minimum possible values
+at-sensor to zero, this method corrects the radiance to output a corrected
+at-sensor values using the equations (not for thermal bands):
<ul>
<li> radiance = (uncorrected_radiance - Lmin) </li>
<li> reflectance = radiance / sun_radiance </li>
</ul>
</p>
-<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>
+<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>
<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):
+<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>
@@ -60,27 +94,41 @@
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>
+ <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>
+<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>
<H2>NOTES</H2>
-<p>In verbose mode (flag -v), the program write basic satellite data and the parameters used in the
-transformations.</p>
+<p>
+In verbose mode (flag -v), the program write basic satellite data and the
+parameters used in the transformations.</p>
-<p>Production date is not an exact value but it is necessary to apply correct calibration constants, which were changed in the dates:
+<p>
+Production date is not an exact value but 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>
@@ -93,11 +141,14 @@
</ul>
</p>
+
<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>
+<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>
<div class="code"><pre>
i.landsat.toar -7 band=203_30 met=p203r030_7x20010620.met
@@ -106,20 +157,39 @@
<p>or</p>
<div class="code"><pre>
-i.landsat.toar -7 band=203_30 product=2004-06-07 date=2001-06-20 solar=64.3242970 gain="HHHLHLHHL"
+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., B.L. Markham and D.L. Helder: Remote Sensing of Environment, vol. 113, 2009.</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>
+ <li>Chander G., B.L. Markham and D.L. Helder: Remote Sensing of
+ Environment, vol. 113, 2009.</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>
@@ -134,7 +204,8 @@
<H2>AUTHOR</H2>
E. Jorge Tizado (ej.tizado unileon es)<br>
-Dept. Biodiversity and Environmental Management, University of León, Spain<BR>
+Dept. Biodiversity and Environmental Management,
+University of León, Spain<BR>
<p>
<i>Last changed: $Date: 2009/09/03 00:00:00 $</i>
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