[GRASS-SVN] r59343 - grass/trunk/raster/r.slope.aspect

svn_grass at osgeo.org svn_grass at osgeo.org
Tue Mar 25 17:16:47 PDT 2014


Author: wenzeslaus
Date: 2014-03-25 17:16:47 -0700 (Tue, 25 Mar 2014)
New Revision: 59343

Modified:
   grass/trunk/raster/r.slope.aspect/r.slope.aspect.html
Log:
r.slope.aspect: remove outdated note about zero slope handling, improve the current info (manual contained two oposite pieces of information)

Modified: grass/trunk/raster/r.slope.aspect/r.slope.aspect.html
===================================================================
--- grass/trunk/raster/r.slope.aspect/r.slope.aspect.html	2014-03-25 20:51:24 UTC (rev 59342)
+++ grass/trunk/raster/r.slope.aspect/r.slope.aspect.html	2014-03-26 00:16:47 UTC (rev 59343)
@@ -20,9 +20,18 @@
 facing. The aspect categories represent the number degrees of east. Category
 and color table files are also generated for the aspect raster map. The aspect
 categories represent the number degrees of east and they increase
-counterclockwise: 90deg is North, 180 is West, 270 is South 360 is East. The
-aspect value 0 is used to indicate undefined aspect in flat areas with slope=0.
+counterclockwise: 90 degrees is North, 180 is West, 270 is South 360 is East.
 
+<p>
+The aspect is not defined for slope equal to zero.
+Thus, most cells with a very small slope end up having category 0,
+45, ..., 360 in <b>aspect</b> output.
+It is possible to reduce the bias in these directions
+by filtering out the aspect in areas where the terrain is almost flat.
+A option <b>min_slp_allowed</b> can be used to specify the minimum slope
+for which aspect is computed. The aspect for all cells with
+slope < <b>min_slp_allowed</b> is set to <i>null</i> (no-data).
+
 <center>
   <img src="aspect_diagram.png" border="0">
 </center>
@@ -149,15 +158,7 @@
 of aspect categories is very uneven, with peaks at 0, 45,..., 360 categories.
 When working with floating point elevation models, no such aspect bias occurs.
 
-<p>
-Because most cells with a very small slope end up having category 0,
-45, ..., 360, it is sometimes possible to reduce the bias in these directions
-by filtering out the aspect in areas where the terrain is almost flat. A new
-option <b>min_slp_allowed</b> was added to specify the minimum slope for which
-aspect is computed. The aspect for all cells with slope <
-<b>min_slp_allowed</b> is set to <i>null</i> (no-data).
 
-
 <h2>REFERENCE</h2>
 
 <ul>



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