cgal/Point_set_processing_3/include/CGAL/compute_average_spacing.h

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// Copyright (c) 2007-09 INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
// 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 3 of the License, or (at your option) any later version.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
//
// Author(s) : Pierre Alliez and Laurent Saboret
#ifndef CGAL_AVERAGE_SPACING_3_H
#define CGAL_AVERAGE_SPACING_3_H
#include <CGAL/Search_traits_3.h>
#include <CGAL/Orthogonal_k_neighbor_search.h>
#include <CGAL/property_map.h>
#include <CGAL/point_set_processing_assertions.h>
#include <iterator>
#include <list>
namespace CGAL {
// ----------------------------------------------------------------------------
// Private section
// ----------------------------------------------------------------------------
namespace internal {
/// Computes average spacing of one query point from K nearest neighbors.
///
/// @commentheading Precondition: k >= 2.
///
/// @commentheading Template Parameters:
/// @param Kernel Geometric traits class.
/// @param Tree KD-tree.
///
/// @return average spacing (scalar).
template < typename Kernel,
typename Tree >
typename Kernel::FT
compute_average_spacing(const typename Kernel::Point_3& query, ///< 3D point whose spacing we want to compute
Tree& tree, ///< KD-tree
unsigned int k) ///< number of neighbors
{
// basic geometric types
typedef typename Kernel::FT FT;
typedef typename Kernel::Point_3 Point;
typedef typename Kernel::Plane_3 Plane;
typedef typename Kernel::Vector_3 Vector;
// types for K nearest neighbors search
typedef Search_traits_3<Kernel> Tree_traits;
typedef Orthogonal_k_neighbor_search<Tree_traits> Neighbor_search;
typedef typename Neighbor_search::iterator Search_iterator;
// performs k + 1 queries (if unique the query point is
// output first). search may be aborted when k is greater
// than number of input points
Neighbor_search search(tree,query,k+1);
Search_iterator search_iterator = search.begin();
FT sum_distances = (FT)0.0;
unsigned int i;
for(i=0;i<(k+1);i++)
{
if(search_iterator == search.end())
break; // premature ending
Point p = search_iterator->first;
sum_distances += std::sqrt(CGAL::squared_distance(query,p));
search_iterator++;
}
// output average spacing
return sum_distances / (FT)i;
}
} /* namespace internal */
// ----------------------------------------------------------------------------
// Public section
// ----------------------------------------------------------------------------
/// Computes average spacing from k nearest neighbors.
///
/// @commentheading Precondition: k >= 2.
///
/// @commentheading Template Parameters:
/// @param InputIterator iterator over input points.
/// @param PointPMap is a model of boost::ReadablePropertyMap with a value_type = Point_3<Kernel>.
/// It can be omitted if InputIterator value_type is convertible to Point_3<Kernel>.
/// @param Kernel Geometric traits class.
/// It can be omitted and deduced automatically from PointPMap value_type.
///
/// @return average spacing (scalar).
// This variant requires the kernel.
template <typename InputIterator,
typename PointPMap,
typename Kernel
>
typename Kernel::FT
compute_average_spacing(
InputIterator first, ///< iterator over the first input point.
InputIterator beyond, ///< past-the-end iterator over the input points.
PointPMap point_pmap, ///< property map InputIterator -> Point_3
unsigned int k, ///< number of neighbors.
const Kernel& /*kernel*/) ///< geometric traits.
{
// basic geometric types
typedef typename Kernel::Point_3 Point;
// types for K nearest neighbors search structure
typedef typename Kernel::FT FT;
typedef Search_traits_3<Kernel> Tree_traits;
typedef Orthogonal_k_neighbor_search<Tree_traits> Neighbor_search;
typedef typename Neighbor_search::Tree Tree;
// precondition: at least one element in the container.
// to fix: should have at least three distinct points
// but this is costly to check
CGAL_point_set_processing_precondition(first != beyond);
// precondition: at least 2 nearest neighbors
CGAL_point_set_processing_precondition(k >= 2);
// Instanciate a KD-tree search.
// Note: We have to convert each input iterator to Point_3.
std::vector<Point> kd_tree_points;
for(InputIterator it = first; it != beyond; it++)
{
Point point = get(point_pmap, it);
kd_tree_points.push_back(point);
}
Tree tree(kd_tree_points.begin(), kd_tree_points.end());
// iterate over input points, compute and output normal
// vectors (already normalized)
FT sum_spacings = (FT)0.0;
unsigned int nb_points = 0;
for(InputIterator it = first; it != beyond; it++)
{
sum_spacings += internal::compute_average_spacing<Kernel,Tree>(get(point_pmap,it),tree,k);
nb_points++;
}
// return average spacing
return sum_spacings / (FT)nb_points;
}
/// @cond SKIP_IN_MANUAL
// This variant deduces the kernel from the iterator type.
template <typename InputIterator,
typename PointPMap
>
typename Kernel_traits<typename boost::property_traits<PointPMap>::value_type>::Kernel::FT
compute_average_spacing(
InputIterator first, ///< iterator over the first input point.
InputIterator beyond, ///< past-the-end iterator over the input points.
PointPMap point_pmap, ///< property map InputIterator -> Point_3
unsigned int k) ///< number of neighbors
{
typedef typename boost::property_traits<PointPMap>::value_type Point;
typedef typename Kernel_traits<Point>::Kernel Kernel;
return compute_average_spacing(
first,beyond,
point_pmap,
k,
Kernel());
}
/// @endcond
/// @cond SKIP_IN_MANUAL
// This variant creates a default point property map = Dereference_property_map.
template < typename InputIterator >
typename Kernel_traits<typename std::iterator_traits<InputIterator>::value_type>::Kernel::FT
compute_average_spacing(
InputIterator first, ///< iterator over the first input point.
InputIterator beyond, ///< past-the-end iterator over the input points.
unsigned int k) ///< number of neighbors.
{
return compute_average_spacing(
first,beyond,
make_dereference_property_map(first),
k);
}
/// @endcond
} //namespace CGAL
#endif // CGAL_AVERAGE_SPACING_3_H