CGAL 6.1.1 - 2D and Surface Function Interpolation

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

##

Given a set of sample points issued from a surface and a query point `p`, the functions `surface_neighbors_3()` compute the neighbors of `p` on the surface within the sample points.

If the sampling is sufficiently dense, the neighbors are provably close to the point `p` on the surface (cf. the manual pages and [2],[5]). They are defined to be the neighbors of `p` in the regular triangulation dual to the power diagram which is equivalent to the intersection of the Voronoi cell of the query point `p` with the tangent plane to the surface at `p`.

The functions `surface_neighbors_certified_3()` also return, in addition, a Boolean value 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 verify that a large enough neighborhood has been considered.

Requirements

1. `Dt` is equivalent to the class `Delaunay_triangulation_3`.
2. `OutputIterator::value_type` is equivalent to `Dt::Point_3`, i.e. a point type.
3. `ITraits` is equivalent to the class `Voronoi_intersection_2_traits_3<K>`.

See also
  `CGAL::Voronoi_intersection_2_traits_3<K>`
  3D Surface Neighbor Coordinates Functions

Implementation

These functions compute the regular triangulation of the sample points and the point `p` using a traits class equivalent to `Voronoi_intersection_2_traits_3<K>`. They determine the neighbors of `p` in this triangulation. The functions which certify the result need to compute, in addition, the Voronoi vertices of the cell of `p` in this diagram.

## Functions
template<class OutputIterator , class InputIterator , class Kernel >
OutputIterator | CGAL::surface_neighbors_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 >
OutputIterator | CGAL::surface_neighbors_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 >
std::pair< OutputIterator, bool > | CGAL::surface_neighbors_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 >
std::pair< OutputIterator, bool > | CGAL::surface_neighbors_certified_3 (InputIterator first, InputIterator beyond, const typename Kernel::Point_3 &p, const typename Kernel::Vector_3 &normal, 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 >
std::pair< OutputIterator, bool > | CGAL::surface_neighbors_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.
template<class OutputIterator , class InputIterator , class ITraits >
std::pair< OutputIterator, bool > | CGAL::surface_neighbors_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 >
OutputIterator | CGAL::surface_neighbors_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 >
OutputIterator | CGAL::surface_neighbors_3 (const Dt &dt, const typename ITraits::Point_2 &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_neighbors_3() [1/4]

template<class Dt , class OutputIterator >

OutputIterator CGAL::surface_neighbors_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_neighbors_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 for the 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_neighbors_3() [2/4]

template<class Dt , class OutputIterator , class ITraits >

OutputIterator CGAL::surface_neighbors_3 | ( | const Dt & | dt,
|  | const typename ITraits::Point_2 & | p,
|  | OutputIterator | out,
|  | const ITraits & | traits,
|  | typename Dt::Cell_handle | start = `typename Dt::Cell_handle()`
| ) |  |

`#include <CGAL/surface_neighbors_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_neighbors_3() [3/4]

template<class OutputIterator , class InputIterator , class ITraits >

OutputIterator CGAL::surface_neighbors_3 | ( | InputIterator | first,
|  | InputIterator | beyond,
|  | const typename ITraits::Point_2 & | p,
|  | OutputIterator | out,
|  | const ITraits & | traits
| ) |  |

`#include <CGAL/surface_neighbors_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_neighbors_3() [4/4]

template<class OutputIterator , class InputIterator , class Kernel >

OutputIterator CGAL::surface_neighbors_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_neighbors_3.h>`

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

`InputIterator::value_type` 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 surface neighbors of `p` are computed which are the neighbors of `p` in the regular triangulation that is dual to the intersection of the 3D Voronoi diagram of \( \mathcal{P}\) with the tangent plane. The point sequence that is computed by the function is placed starting at `out`. The function returns an iterator that is placed past-the-end of the resulting point sequence.

## ◆ surface_neighbors_certified_3() [1/2]

template<class OutputIterator , class InputIterator , class ITraits >

std::pair< OutputIterator, bool > CGAL::surface_neighbors_certified_3 | ( | InputIterator | first,
|  | InputIterator | beyond,
|  | const typename ITraits::Point_2 & | p,
|  | OutputIterator | out,
|  | const ITraits & | traits
| ) |  |

`#include <CGAL/surface_neighbors_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>`. There is no parameter `max_distance`.

## ◆ surface_neighbors_certified_3() [2/2]

template<class OutputIterator , class InputIterator , class Kernel >

std::pair< OutputIterator, bool > CGAL::surface_neighbors_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_neighbors_3.h>`

Similar to the first function.

The additional third 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 be `(p,normal)`. It is `false` otherwise.