[GRASS-SVN] r30270 - grass/trunk/raster/r.drain

[svn_grass at osgeo.org]

Author: epatton
Date: 2008-02-20 11:57:17 -0500 (Wed, 20 Feb 2008)
New Revision: 30270

Modified:
   grass/trunk/raster/r.drain/description.html
Log:
Updated manpage to warn about module behavior at region boundary; typos corrected, reorganized sections

Modified: grass/trunk/raster/r.drain/description.html
===================================================================
--- grass/trunk/raster/r.drain/description.html	2008-02-20 16:25:56 UTC (rev 30269)
+++ grass/trunk/raster/r.drain/description.html	2008-02-20 16:57:17 UTC (rev 30270)
@@ -7,24 +7,24 @@
 <EM><A HREF="r.cost.html">r.cost</A></EM> program.
 
 The <b>output</b> result (also a raster map layer) will show one or more 
-least-cost paths between each user-provided location(s) and the low spot 
+least-cost paths between each user-provided location(s) and the minima 
 (low category values) in the <B>input</B> map. By default, the <B>output</B>
 will be an integer CELL map with <tt>1</tt> along the least cost path,
 and null cells elsewhere.
 
 <P>
-With the <B>-c</B> (<EM>copy</EM>) flag, the input map cells values are
+With the <B>-c</B> (<EM>copy</EM>) flag, the input map cell values are
 copied verbatim along the path. With the <B>-a</B> (<EM>accumulate</EM>)
-flag, the accumulated cells value from the starting point up to the current
-cell is written on output. With the <B>-c</B> and the <B>-a</B> flags the
+flag, the accumulated cell value from the starting point up to the current
+cell is written on output. With either the <B>-c</B> or the <B>-a</B> flags, the
 <B>output</B> map is created with the same cell type as the <B>input</B> map (integer,
 float or double).
-With the <B>-n</B> (<EM>number</EM>) flag, the cells are numbered from the
+With the <B>-n</B> (<EM>number</EM>) flag, the cells are numbered consecutively from the
 starting point to the final point.
 The <B>-c</B>, <B>-a</B>, and <B>-n</B> flags are mutually incompatible.
 
 <P>
-The path is calculated by choosing the stepper "slope" between adjacent
+The path is calculated by choosing the steeper "slope" between adjacent
 cells. The slope calculation accurately acounts for the variable scale in
 lat-lon projections.
 
@@ -37,8 +37,25 @@
 Up to 1024 starting points can be input from a combination of the
 <B>coordinate</B> and <B>vector_points</B> parameters.
 
+<H2>NOTES</H2>
 
+<EM>r.drain</EM> currently finds only the lowest point
+(the cell having the smallest category value) in the 
+input file that can be reached through directly adjacent cells 
+that are less than or equal in value to the cell reached immediately 
+prior to it; therefore, it will not necessarily reach the lowest point 
+in the input file. It currently finds <EM>pits</EM> in the data, rather 
+than the lowest point in the entire input map. The <em>r.fill.dir</em>,
+<em>r.terraflow</em>, and <em>r.basins.fill</em> modules can be used to
+fill in subbasins prior to processing with <em>r.drain</em>.
 
+<P>
+
+<EM>r.drain</EM> will not give sane results at the region boundary. On outer rows
+and columns bordering the edge of the region, the flow direction is always directly out 
+of the map. In this case, the user could try adjusting the region extents slightly with 
+<EM>g.region</EM> to allow additional outlet paths for <EM>r.drain</EM>.
+
 <H2>EXAMPLES</H2>
 
 Consider the following example: 
@@ -140,16 +157,6 @@
 
 <H2>BUGS</H2>
 
-<EM>r.drain</EM> currently finds only the lowest point
-(the cell having the smallest category value) in the 
-input file that can be reached through directly adjacent cells 
-that are less than or equal in value to the cell reached immediately 
-prior to it; therefore, it will not necessarily reach the lowest point 
-in the input file. It currently finds <EM>pits</EM> in the data, rather 
-than the lowest point present. Thr <em>r.fill.dir</em> and
-<em>r.basins.fill</em> modules can be used to fill in subbasins prior to
-processing with <em>r.drain</em>.
-
 <P>
 Sometimes, when the differences among integer cell category values in the
 <EM><A HREF="r.cost.html">r.cost</a></EM> cumulative cost surface output are 
@@ -172,6 +179,7 @@
 <EM><A HREF="r.cost.html">r.cost</A></EM>,
 <EM><A HREF="r.fill.dir.html">r.fill.dir</A></EM>,
 <EM><A HREF="r.basins.fill.html">r.basins.fill</A></EM>,
+<EM><A HREF="r.terraflow.html">r.terraflow</A></EM>,
 <EM><A HREF="r.mapcalc.html">r.mapcalc</A></EM>,
 <EM><A HREF="r.walk.html">r.walk</A></EM>