[GRASS-SVN] r35913 - in grass-addons/vector: . v.swathwidth

[svn_grass at osgeo.org]

Author: hamish
Date: 2009-02-17 19:36:24 -0500 (Tue, 17 Feb 2009)
New Revision: 35913

Added:
   grass-addons/vector/v.swathwidth/
   grass-addons/vector/v.swathwidth/v.swathwidth
Log:
v.swathwidth from David Finlayson (with permission)

Added: grass-addons/vector/v.swathwidth/v.swathwidth
===================================================================
--- grass-addons/vector/v.swathwidth/v.swathwidth	                        (rev 0)
+++ grass-addons/vector/v.swathwidth/v.swathwidth	2009-02-18 00:36:24 UTC (rev 35913)
@@ -0,0 +1,111 @@
+#!/bin/bash
+############################################################################
+#
+# MODULE:       v.swathwidth
+# AUTHOR(S):	David Finlayson (with help from Hamish via the list), 2006
+#               david.p.finlayson at gmail.com
+#
+# PURPOSE:	Creates a vector map representing the sea bottom coverage of
+#               a multibeam survey
+#
+# COPYRIGHT:	(C) 2006 by the GRASS Development Team
+#
+#		This program is free software under the GNU General Public
+#		License (>=v2). Read the file COPYING that comes with GRASS
+#		for details.
+#
+#############################################################################
+#
+# April 2006 - First version of the script posted to GRASS
+
+#%Module
+#%  description: Estimate multibeam bottom coverage (swath width) along a survey track line
+#%End
+#%option
+#% key: trackline
+#% type: string
+#% gisprompt: old,vector,vector
+#% description: Vector line representing survey track
+#% required : yes
+#%end
+#%option
+#% key: elevation
+#% type: string
+#% gisprompt: old,cell,raster
+#% description: Raster DEM of survey area (negative values = below sea level)
+#% required : yes
+#%end
+#%option
+#% key: out
+#% type: string
+#% gisprompt: new,vector
+#% description: Output vector for result
+#% required : yes
+#%end
+#%option
+#% key: beamwidth
+#% type: double
+#% description: Beam width as a multiple of water depth
+#% required : no
+#% answer: 3
+#%end
+#%option
+#% key: distance
+#% type: double
+#% description: Along track distance between swath width estimates
+#% required : no
+#% answer: 100
+#%end
+
+# Run g.parser
+if [ "$1" != "@ARGS_PARSED@" ] ; then
+  PARSER=`which g.parser`
+  exec $PARSER "$0" "$@"
+fi
+
+# Save the region and then reduce the size of the region as much as
+# possible to save raster processing time
+g.remove region=temp_swath 2>&1 /dev/null
+g.region save=temp_swath  2>&1 /dev/null
+g.region vect=$GIS_OPT_TRACKLINE 2>&1 /dev/null
+
+# Convert the raster elevation DEM into units of "swath widths"
+r.mapcalc "temp_swath = if($GIS_OPT_ELEVATION < 0, -1 * $GIS_OPT_ELEVATION * $GIS_OPT_BEAMWIDTH, null())"
+
+# Split the track line into segments where swath width will be visualized
+v.to.points input=$GIS_OPT_TRACKLINE output=temp_point dmax=$GIS_OPT_DISTANCE --o 2>&1 /dev/null
+
+# Add a column to hold the swath width values
+v.db.addcol map=temp_point layer=2 columns="width double" 2>&1 /dev/null
+
+# Load the swath width values into the table
+v.what.rast vect=temp_point rast=temp_swath layer=2 col=width 2>&1 /dev/null
+
+# To visualize the swath width, buffer the nodes of the trackline by swath width
+v.buffer input=temp_point output=temp_circles type=point layer=2 bufcol=width --o 2>&1 /dev/null
+
+# The output of v.buffer currently does not join together the areas of all of the buffer circles
+# with a union command (I'm not sure what it is doing actually). The following code dissolves
+# all of the little polygons created by v.buffer into as few shapes as possible (union of all 
+# shapes). This section is basically written by Hamish via the mailing list. Thanks!
+
+# Break polygons at intersections (flatten circles)
+v.clean input=temp_circles out=temp_circles2 tool=break --o 2>&1 /dev/null
+
+# Add centroids to each polygon to make areas
+v.category input=temp_circles2 output=temp_circles3 step=0 --o 2>&1 /dev/null 
+
+# Disolve common boundaries (union of areas)
+v.extract -d type=area in=temp_circles3 out=temp_circles4 --o 2>&1 /dev/null
+
+# Reset the region
+g.region region=temp_swath 2>&1 /dev/null
+
+# Clean up
+g.rename vect=temp_circles4,$GIS_OPT_OUT --o
+g.mremove -f vect=temp_* 2>&1 /dev/null
+g.remove rast=temp_swath 2>&1 /dev/null
+
+echo Swath width map written to: $GIS_OPT_OUT
+
+# end


Property changes on: grass-addons/vector/v.swathwidth/v.swathwidth
___________________________________________________________________
Name: svn:executable
   + *
Name: svn:eol-style
   + native