diff --git a/src/Prep/DemChop/fillvoids.cxx b/src/Prep/DemChop/fillvoids.cxx
new file mode 100644
index 00000000..c0f81a6a
--- /dev/null
+++ b/src/Prep/DemChop/fillvoids.cxx
@@ -0,0 +1,126 @@
+// fillvoids.cxx -- fill voids in one array from data points of another array.
+//
+// Written by Curtis Olson, started November 2005.
+//
+// Copyright (C) 2005  Curtis L. Olson  - http://www.flightgear.org/~curt
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#include <simgear/compiler.h>
+
+#include STL_STRING
+
+#include <simgear/bucket/newbucket.hxx>
+#include <simgear/debug/logstream.hxx>
+#include <simgear/misc/sg_path.hxx>
+
+#include <Array/array.hxx>
+
+SG_USING_STD(cout);
+SG_USING_STD(string);
+
+
+int main(int argc, char **argv) {
+    sglog().setLogLevels( SG_ALL, SG_WARN );
+
+    if ( argc != 3 ) {
+	cout << "Usage " << argv[0] << " <src_array> <fill_array_base>"
+             << endl;
+	exit(-1);
+    }
+
+    string src_array_path = argv[1];
+    string fill_base_path = argv[2];
+
+    // compute the fill array path
+    SGPath tmp1( src_array_path );
+    string tmp2 = tmp1.base(); // strip .gz
+    cout << "tmp2 = " << tmp2 << endl;
+    string tmp3 = SGPath(tmp2).base(); // strip .arr
+    cout << "tmp3 = " << tmp3 << endl;
+    string file = SGPath(tmp3).file();
+    cout << "file = " << file << endl;
+    long int index = atoi(file.c_str());
+    SGBucket bucket( index );
+    SGPath tmp4( fill_base_path );
+    tmp4.append( bucket.gen_base_path() );
+    tmp4.append( file );
+    string tmp5 = tmp1.dir();
+    string tmp6 = SGPath(tmp5).dir();
+    string tmp7 = SGPath(tmp6).dir();
+    cout << "tmp7 = " << tmp7 << endl;
+
+    cout << "Index = " << index << endl;
+    cout << "fill array = " << tmp4.str() << endl;
+
+    // open the source array
+    TGArray src_array;
+    src_array.open( tmp3 );
+    src_array.parse( bucket );
+    if ( !src_array.is_open() ) {
+      cout << "Unable to open source array " << tmp3 << endl;
+      return -1;
+    }
+
+    // open the fill array
+    TGArray fill_array;
+    fill_array.open( tmp4.str() );
+    fill_array.parse( bucket );
+    if ( !fill_array.is_open() ) {
+      cout << "no fill array, nothing to do " << tmp4.str() << endl;
+      return 0;
+    }
+
+    // traverse the source array and lookup replacement values for any voids
+    bool has_void = false;
+    for ( int i = 0; i < src_array.get_cols(); ++i ) {
+      for ( int j = 0; j < src_array.get_rows(); ++j ) {
+	int src_elev = src_array.get_array_elev(i, j);
+	if ( src_elev < -9000 ) {
+	  has_void = true;
+	  cout << "We have a void = " << src_elev << endl;
+	  int fill_elev = fill_array.get_array_elev(i, j);
+	  cout << "Replacing with " << fill_elev << endl;
+	  src_array.set_array_elev(i, j, fill_elev);
+	}
+      }
+    }
+
+    // write out the new data file if we filled any voids
+    if ( has_void ) {
+      cout << "Has voids, writing file ..." << endl;
+      bool result = src_array.write( tmp7, bucket );
+      if ( result ) {
+	// filled data written to new file name, now replace old file
+	SGPath tmp_file(tmp3);
+	tmp_file.concat(".arr.new.gz");
+	SGPath orig_file(tmp3);
+	orig_file.concat(".arr.gz");
+	rename( tmp_file.str().c_str(), orig_file.str().c_str() );
+      }
+    } else {
+      cout << "no voids" << endl;
+    }
+
+    return 0;
+}
+
+