CGAL 6.1.1 - 2D and Surface Function Interpolation

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Functions
3D Surface Neighbor Coordinates Functions
Reference Manual » Surface Neighbor and Surface Neighbor Coordinate Computation

##

The functions `surface_neighbor_coordinates_3()` compute natural neighbor coordinates for surface points associated to a finite set of sample points issued from the surface.

The coordinates are computed from the intersection of the Voronoi cell of the query point `p` with the tangent plane to the surface at `p`. If the sampling is sufficiently dense, the coordinate system meets the properties described in the manual pages and in [2],[5]. The query point `p` needs to lie inside the convex hull of the projection of the sample points onto the tangent plane at `p`.

The functions `surface_neighbor_coordinates_certified_3()` return, in addition, a second Boolean value (the fourth value of the quadruple) that certifies whether or not, the Voronoi cell of `p` can be affected by points that lie outside the input range, i.e. outside the ball centered on `p` passing through the furthest sample point from `p` in the range `[first, beyond)`. If the sample points are collected by a `k`-nearest neighbor or a range search query, this permits to check whether the neighborhood which has been considered is large enough.

Requirements

1. `Dt` is equivalent to the class `Delaunay_triangulation_3`.
2. The value type of `OutputIterator` is equivalent to `std::pair<Dt::Point_3, Dt::Geom_traits::FT>`, i.e. a pair associating a point and its natural neighbor coordinate.
3. `ITraits` is equivalent to the class `Voronoi_intersection_2_traits_3<K>`.

See also
  `CGAL::linear_interpolation()`
  `CGAL::sibson_c1_interpolation()`
  `CGAL::farin_c1_interpolation()`
  `CGAL::Voronoi_intersection_2_traits_3<K>`
  3D Surface Neighbors Functions

Implementation

This functions construct the regular triangulation of the input points instantiated with `Voronoi_intersection_2_traits_3<Kernel>` or `ITraits` if provided. They return the result of the function call `PkgInterpolationRegularNeighborCoordinates2` with the regular triangulation and `p` as arguments.

## Functions
template<class OutputIterator , class InputIterator , class Kernel >
CGAL::Triple< OutputIterator, typename Kernel::FT, bool > | CGAL::surface_neighbor_coordinates_3 (InputIterator first, InputIterator beyond, const typename Kernel::Point_3 &p, const typename Kernel::Vector_3 &normal, OutputIterator out, const Kernel &K)
| The sample points \( \mathcal{P}\) are provided in the range `[first, beyond)`.
template<class OutputIterator , class InputIterator , class ITraits >
CGAL::Triple< OutputIterator, typename ITraits::FT, bool > | CGAL::surface_neighbor_coordinates_3 (InputIterator first, InputIterator beyond, const typename ITraits::Point_2 &p, OutputIterator out, const ITraits &traits)
| Same as above only that the traits class must be instantiated by the user.
template<class OutputIterator , class InputIterator , class Kernel >
CGAL::Quadruple< OutputIterator, typename Kernel::FT, bool, bool > | CGAL::surface_neighbor_coordinates_certified_3 (InputIterator first, InputIterator beyond, const typename Kernel::Point_3 &p, const typename Kernel::Vector_3 &normal, OutputIterator out, const Kernel &K)
| Similar to the first function.
template<class OutputIterator , class InputIterator , class Kernel >
CGAL::Quadruple< OutputIterator, typename Kernel::FT, bool, bool > | CGAL::surface_neighbor_coordinates_certified_3 (InputIterator first, InputIterator beyond, const typename Kernel::Point_3 &p, const typename Kernel::FT &max_distance, OutputIterator out, const Kernel &kernel)
| Same as above except that this function takes the maximal distance from p to the points in the range `[first, beyond)` as additional parameter.
template<class OutputIterator , class InputIterator , class ITraits >
CGAL::Quadruple< OutputIterator, typename ITraits::FT, bool, bool > | CGAL::surface_neighbor_coordinates_certified_3 (InputIterator first, InputIterator beyond, const typename ITraits::Point_2 &p, OutputIterator out, const ITraits &traits)
| Same as above only that the traits class must be instantiated by the user and without the parameter `max_distance`.
template<class OutputIterator , class InputIterator , class ITraits >
CGAL::Quadruple< OutputIterator, typename ITraits::FT, bool, bool > | CGAL::surface_neighbor_coordinates_certified_3 (InputIterator first, InputIterator beyond, const typename ITraits::Point_2 &p, const typename ITraits::FT &max_distance, OutputIterator out, const ITraits &traits)
| Same as above with the parameter `max_distance`.
template<class Dt , class OutputIterator >
CGAL::Triple< OutputIterator, typename Dt::Geom_traits::FT, bool > | CGAL::surface_neighbor_coordinates_3 (const Dt &dt, const typename Dt::Geom_traits::Point_3 &p, const typename Dt::Geom_traits::Vector_3 &normal, OutputIterator out, typename Dt::Cell_handle start=typename Dt::Cell_handle())
| Computes the surface neighbor coordinates with respect to the points that are vertices of the Delaunay triangulation `dt`.
template<class Dt , class OutputIterator , class ITraits >
CGAL::Triple< OutputIterator, typename Dt::Geom_traits::FT, bool > | CGAL::surface_neighbor_coordinates_3 (const Dt &dt, const typename Dt::Geom_traits::Point_3 &p, OutputIterator out, const ITraits &traits, typename Dt::Cell_handle start=typename Dt::Cell_handle())
| Same as above only that the parameter traits instantiates the geometric traits class.

## Function Documentation

## ◆ surface_neighbor_coordinates_3() [1/4]

template<class Dt , class OutputIterator >

CGAL::Triple< OutputIterator, typename Dt::Geom_traits::FT, bool > CGAL::surface_neighbor_coordinates_3 | ( | const Dt & | dt,
|  | const typename Dt::Geom_traits::Point_3 & | p,
|  | const typename Dt::Geom_traits::Vector_3 & | normal,
|  | OutputIterator | out,
|  | typename Dt::Cell_handle | start = `typename Dt::Cell_handle()`
| ) |  |

`#include <CGAL/surface_neighbor_coordinates_3.h>`

Computes the surface neighbor coordinates with respect to the points that are vertices of the Delaunay triangulation `dt`.

The type `Dt` must be equivalent to `Delaunay_triangulation_3<Gt, Tds>`. The optional parameter `start` is used as a starting place for the search of the conflict zone. It may be the result of the call `dt.locate(p)`. This function instantiates the template parameter `ITraits` to be `Voronoi_intersection_2_traits_3<Dt::Geom_traits>`.

This function allows to filter some potential neighbors of the query point `p` from \( \mathcal{P}\) via its three-dimensional Delaunay triangulation. All surface neighbors of `p` are necessarily neighbors in the Delaunay triangulation of \( \mathcal{P} \cup \{p\}\).

## ◆ surface_neighbor_coordinates_3() [2/4]

template<class Dt , class OutputIterator , class ITraits >

CGAL::Triple< OutputIterator, typename Dt::Geom_traits::FT, bool > CGAL::surface_neighbor_coordinates_3 | ( | const Dt & | dt,
|  | const typename Dt::Geom_traits::Point_3 & | p,
|  | OutputIterator | out,
|  | const ITraits & | traits,
|  | typename Dt::Cell_handle | start = `typename Dt::Cell_handle()`
| ) |  |

`#include <CGAL/surface_neighbor_coordinates_3.h>`

Same as above only that the parameter traits instantiates the geometric traits class.

Its type `ITraits` must be equivalent to `Voronoi_intersection_2_traits_3<K>`.

## ◆ surface_neighbor_coordinates_3() [3/4]

template<class OutputIterator , class InputIterator , class ITraits >

CGAL::Triple< OutputIterator, typename ITraits::FT, bool > CGAL::surface_neighbor_coordinates_3 | ( | InputIterator | first,
|  | InputIterator | beyond,
|  | const typename ITraits::Point_2 & | p,
|  | OutputIterator | out,
|  | const ITraits & | traits
| ) |  |

`#include <CGAL/surface_neighbor_coordinates_3.h>`

Same as above only that the traits class must be instantiated by the user.

`ITraits` must be equivalent to `Voronoi_intersection_2_traits_3<K>`.

## ◆ surface_neighbor_coordinates_3() [4/4]

template<class OutputIterator , class InputIterator , class Kernel >

CGAL::Triple< OutputIterator, typename Kernel::FT, bool > CGAL::surface_neighbor_coordinates_3 | ( | InputIterator | first,
|  | InputIterator | beyond,
|  | const typename Kernel::Point_3 & | p,
|  | const typename Kernel::Vector_3 & | normal,
|  | OutputIterator | out,
|  | const Kernel & | K
| ) |  |

`#include <CGAL/surface_neighbor_coordinates_3.h>`

The sample points \( \mathcal{P}\) are provided in the range `[first, beyond)`.

The value type of `InputIterator` is the point type `Kernel::Point_3`. The tangent plane is defined by the point `p` and the vector `normal`. The parameter `K` determines the kernel type that will instantiate the template parameter of `Voronoi_intersection_2_traits_3<K>`.

The natural neighbor coordinates for `p` are computed in the power diagram that results from the intersection of the `3D` Voronoi diagram of \( \mathcal{P}\) with the tangent plane. The sequence of point/coordinate pairs that is computed by the function is placed starting at `out`. The function returns a triple with an iterator that is placed past-the-end of the resulting sequence of point/coordinate pairs, the normalization factor of the coordinates and a Boolean value which is set to true iff the coordinate computation was successful, i.e. if `p` lies inside the convex hull of the projection of the points \( \mathcal{P}\) onto the tangent plane.

Examples
  Interpolation/surface_neighbor_coordinates_3.cpp.

## ◆ surface_neighbor_coordinates_certified_3() [1/2]

template<class OutputIterator , class InputIterator , class ITraits >

CGAL::Quadruple< OutputIterator, typename ITraits::FT, bool, bool > CGAL::surface_neighbor_coordinates_certified_3 | ( | InputIterator | first,
|  | InputIterator | beyond,
|  | const typename ITraits::Point_2 & | p,
|  | OutputIterator | out,
|  | const ITraits & | traits
| ) |  |

`#include <CGAL/surface_neighbor_coordinates_3.h>`

Same as above only that the traits class must be instantiated by the user and without the parameter `max_distance`.

`ITraits` must be equivalent to `Voronoi_intersection_2_traits_3<K>`.

## ◆ surface_neighbor_coordinates_certified_3() [2/2]

template<class OutputIterator , class InputIterator , class Kernel >

CGAL::Quadruple< OutputIterator, typename Kernel::FT, bool, bool > CGAL::surface_neighbor_coordinates_certified_3 | ( | InputIterator | first,
|  | InputIterator | beyond,
|  | const typename Kernel::Point_3 & | p,
|  | const typename Kernel::Vector_3 & | normal,
|  | OutputIterator | out,
|  | const Kernel & | K
| ) |  |

`#include <CGAL/surface_neighbor_coordinates_3.h>`

Similar to the first function.

The additional fourth return value is `true` if the furthest point in the range `[first, beyond)` is further away from `p` than twice the distance from `p` to the furthest vertex of the intersection of the Voronoi cell of `p` with the tangent plane defined by `(p,normal)`. It is `false` otherwise.