i.gensigset manual: explain 'Unreliable clustering' warning; HTML cosmetics

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@60960 15284696-431f-4ddb-bdfa-cd5b030d7da7

imagery/i.gensigset/i.gensigset.html

@@ -2,7 +2,6 @@
 
 <em>i.gensigset</em>
 is a non-interactive method for generating input into
-
 <em><a href="i.smap.html">i.smap</a>.</em>
 
 It is used as the first pass in the a two-pass
@@ -12,7 +11,6 @@ regions already classified.  <em>i.gensigset</em> will then
 extract spectral signatures from an image based on the
 classification of the pixels in the training map and make
 these signatures available to
-
 <em><a href="i.smap.html">i.smap</a>.</em>
 
 
@@ -31,7 +29,6 @@ final classified map.
 
 <dd>ground truth training map
 
-
 <p>
 This raster layer, supplied as input by the user, has some
 of its pixels already classified, and the rest (probably
@@ -55,7 +52,6 @@ to define the areas
 representative
 of the classes in the image.
 
-
 <p>
 At present, there is no fully-interactive tool specifically
 designed for producing this layer.
@@ -107,7 +103,6 @@ selected.
 <dd>maximum number of sub-signatures in any class
 
 <br>
-
 default: 5
 
 <p>
@@ -119,7 +114,6 @@ starts with a maximum number of subclasses and reduces this
 number to a minimal number of subclasses which are
 spectrally distinct.  The user has the option to set this
 starting value with this option.
-
 </dl>
 
 
@@ -188,59 +182,60 @@ and covariance of the subclasses are computed using the
 expectation maximization (EM) algorithm 
 [<a href="#dempster77">2</a>,<a href="#redner84">3</a>].  
 
+<h2>WARNINGS</h2>
 
-<h2>REFERENCES</h2>
+If warnings like this occur, reducing the remaining classes to 0:
 
-<ol>
+<div class="code"><pre>
+...
+WARNING: Removed a singular subsignature number 1 (4 remain)
+WARNING: Removed a singular subsignature number 1 (3 remain)
+WARNING: Removed a singular subsignature number 1 (2 remain)
+WARNING: Removed a singular subsignature number 1 (1 remain)
+WARNING: Unreliable clustering. Try a smaller initial number of clusters
+WARNING: Removed a singular subsignature number 1 (-1 remain)
+WARNING: Unreliable clustering. Try a smaller initial number of clusters
+Number of subclasses is 0
+</pre></div>
+
+then the user should check for:
+<ul>
+<li>the range of the input data should be between 0 and 100 or 255 but not
+  between 0.0 and 1.0 (<em>r.info</em> and <em>r.univar</em> show the range)</li>
+<li>the training areas need to contain a sufficient amount of pixels</li>
+</ul>
 
-<li><A NAME="rissanen83">J. Rissanen,</a>
-"A Universal Prior for Integers and Estimation by Minimum
-Description Length,"
-<em>Annals of Statistics,</em>
-vol. 11, no. 2, pp. 417-431, 1983.
 
+<h2>REFERENCES</h2>
 
+<ul>
+<li><A NAME="rissanen83">J. Rissanen,</a>
+"A Universal Prior for Integers and Estimation by Minimum Description Length,"
+<em>Annals of Statistics,</em> vol. 11, no. 2, pp. 417-431, 1983.
 <li><A NAME="dempster77">A. Dempster, N. Laird and D. Rubin,</a>
 "Maximum Likelihood from Incomplete Data via the EM Algorithm,"
-<em>J. Roy. Statist. Soc. B,</em>
-vol. 39, no. 1, pp. 1-38, 1977.
-
+<em>J. Roy. Statist. Soc. B,</em> vol. 39, no. 1, pp. 1-38, 1977.
 <li><A NAME="redner84">E. Redner and H. Walker,</a>
 "Mixture Densities, Maximum Likelihood and the EM Algorithm,"
-<em>SIAM Review,</em>
-vol. 26, no. 2, April 1984.
-
-</ol>
+<em>SIAM Review,</em> vol. 26, no. 2, April 1984.
+</ul>
 
 <h2>SEE ALSO</h2>
 
-<em><a href="i.group.html">i.group</a></em>
-for creating groups and subgroups
-
-
-<p>
-<em><a href="wxGUI.vdigit.html">wxGUI vector digitizer</a></em>
-and
-<em><a href="r.digit.html">r.digit</a></em>
-for interactively creating the training map.
-
-
-<p>
-<em><a href="i.smap.html">i.smap</a></em>
-for creating a final classification layer from the signatures
-generated by <em>i.gensigset.</em>
-
+<em>
+<a href="i.group.html">i.group</a>,
+<a href="i.smap.html">i.smap</a>,
+<a href="r.info.html">r.info</a>,
+<a href="r.univar.html">r.univar</a>,
+<a href="wxGUI.vdigit.html">wxGUI vector digitizer</a>
+</em>
 
 <h2>AUTHORS</h2>
 
 Charles Bouman, 
-School of 
-Electrical Engineering, 
-Purdue University
+School of Electrical Engineering, Purdue University
 <br>
-
 Michael Shapiro,
-U.S.Army Construction Engineering 
-Research Laboratory
+U.S.Army Construction Engineering Research Laboratory
 
 <p><i>Last changed: $Date$</i>