\( \newcommand{\E}{\mathrm{E}} \) \( \newcommand{\A}{\mathrm{A}} \) \( \newcommand{\R}{\mathrm{R}} \) \( \newcommand{\N}{\mathrm{N}} \) \( \newcommand{\Q}{\mathrm{Q}} \) \( \newcommand{\Z}{\mathrm{Z}} \) \( \def\ccSum #1#2#3{ \sum_{#1}^{#2}{#3} } \def\ccProd #1#2#3{ \sum_{#1}^{#2}{#3} }\)

CGAL 4.8 - 2D and Surface Function Interpolation

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Modules | Classes | Functions
Interpolation Functions
2D and Surface Function Interpolation Reference

##

## Modules
| Sibson gradient fitting functions
| These functions approximate the gradient of a function at a point `p` given natural neighbor coordinates for `p` and its neighbors' function values.

## Classes
class | CGAL::Interpolation_gradient_fitting_traits_2< K >
| `Interpolation_gradient_fitting_traits_2` is a model for the concepts `InterpolationTraits` and `GradientFittingTraits`. More...
class | CGAL::Interpolation_traits_2< K >
| `Interpolation_traits_2` is a model for the concept `InterpolationTraits` and can be used to instantiate the geometric traits class of interpolation methods applied on a bivariate function over a two-dimensional domain. More...

## Functions
template<class RandomAccessIterator , class Functor , class GradFunctor , class Traits >
Functor::result_type | CGAL::farin_c1_interpolation (RandomAccessIterator first, RandomAccessIterator beyond, const typename std::iterator_traits< RandomAccessIterator >::value_type::second_type &norm, const typename std::iterator_traits< ForwardIterator >::value_type::first_type &p, Functor function_value, GradFunctor function_gradient, const Traits &traits)
| generates the interpolated function value computed by Farin's interpolant. More...
template<class ForwardIterator , class Functor >
Functor::result_type::first_type | CGAL::linear_interpolation (ForwardIterator first, ForwardIterator beyond, const typename std::iterator_traits< ForwardIterator >::value_type::second_type &norm, Functor function_values)
| The function `linear_interpolation()` computes the weighted sum of the function values which must be provided via a functor. More...
template<class ForwardIterator , class Functor , class GradFunctor , class Traits >
Functor::result_type | CGAL::quadratic_interpolation (ForwardIterator first, ForwardIterator beyond, const typename std::iterator_traits< ForwardIterator >::value_type::second_type &norm, const typename std::iterator_traits< ForwardIterator >::value_type::first_type &p, Functor function_value, GradFunctor function_gradient, const Traits &traits)
| The function `quadratic_interpolation()` generates the interpolated function value as the weighted sum of the values plus a linear term in the gradient for each point of the point/coordinate pairs in the range `[first, beyond)`. More...
template<class ForwardIterator , class Functor , class GradFunctor , class Traits >
std::pair< typename Functor::result_type, bool > | CGAL::sibson_c1_interpolation (ForwardIterator first, ForwardIterator beyond, const typename std::iterator_traits< ForwardIterator >::value_type::second_type &norm, const typename std::iterator_traits< ForwardIterator >::value_type::first_type &p, Functor function_value, GradFunctor function_gradient, const Traits &traits)
| The function `sibson_c1_interpolation()` generates the interpolated function value at the point `p`, using functors for the function values and the gradients, by applying Sibson's \( Z^1\) interpolant. More...
template<class ForwardIterator , class Functor , class GradFunctor , class Traits >
Functor::result_type | CGAL::sibson_c1_interpolation_square (ForwardIterator first, ForwardIterator beyond, const typename std::iterator_traits< ForwardIterator >::value_type::second_type &norm, const typename std::iterator_traits< ForwardIterator >::value_type::first_type &p, Functor function_value, GradFunctor function_gradient, const Traits &traits)
| The same as `sibson_c1_interpolation()` except that no square root operation is needed for FT.

## Function Documentation

template<class RandomAccessIterator , class Functor , class GradFunctor , class Traits >

Functor::result_type CGAL::farin_c1_interpolation | ( | RandomAccessIterator | first,
|  | RandomAccessIterator | beyond,
|  | const typename std::iterator_traits< RandomAccessIterator >::value_type::second_type & | norm,
|  | const typename std::iterator_traits< ForwardIterator >::value_type::first_type & | p,
|  | Functor | function_value,
|  | GradFunctor | function_gradient,
|  | const Traits & | traits
| ) |  |

generates the interpolated function value computed by Farin's interpolant.

Precondition
  `norm` \( \neq0\). `function_value(p).second == true` for all points `p` of the point/coordinate pairs in the range `[first, beyond)`.
  The range `[first, beyond)` contains either one or more than three elements. The function `farin_c1_interpolation()` interpolates the function values and the gradients that are provided by functors using the method described in [4].

Parameters

The value type of `RandomAccessIterator` is a pair associating a point to a (non-normalized) barycentric coordinate. See `sibson_c1_interpolation()` for the other parameters.

Requirements

Same requirements as for `sibson_c1_interpolation()` only the iterator must provide random access and `Traits::FT` does not need to provide the square root operation.

See Also
  `CGAL::Data_access<Map>`
  `CGAL::linear_interpolation()`
  `CGAL::sibson_c1_interpolation()`
  Sibson gradient fitting functions
  `CGAL::Interpolation_traits_2<K>`
  `CGAL::natural_neighbor_coordinates_2()`
  `CGAL::regular_neighbor_coordinates_2()`
  3D Surface Neighbor Coordinates Functions

`#include <CGAL/interpolation_functions.h>`

template<class ForwardIterator , class Functor >

Functor::result_type::first_type CGAL::linear_interpolation | ( | ForwardIterator | first,
|  | ForwardIterator | beyond,
|  | const typename std::iterator_traits< ForwardIterator >::value_type::second_type & | norm,
|  | Functor | function_values
| ) |  |

The function `linear_interpolation()` computes the weighted sum of the function values which must be provided via a functor.

Template Parameters

  ForwardIterator | must have as value type a pair associating a point to a (non-normalized) barycentric coordinate, that is `std::iterator_traits<ForwardIterator>::value_type::first_type` is equivalent to a point and `std::iterator_traits<ForwardIterator>::value_type::second_type` is a field number type.
  Functor | The type `Functor::argument_type` must be equivalent to `std::iterator_traits<ForwardIterator>::value_type::first_type` and `Functor::result_type` is a pair of the function value type and a Boolean value. The function value type must provide a multiplication and addition operation with the field number type `std::iterator_traits<ForwardIterator>::value_type::second_type` and a constructor with argument `0`.

A model of the functor is provided by the struct `Data_access`. It must be instantiated accordingly with an associative container (e.g. `std::map`) having the point type as `key_type` and the function value type as `mapped_type`.

Parameters

  first,beyond | are the iterator range for the weighted input points.
  norm | is the normalization factor. `norm` \( \neq0\).
  function_values | is a functor that allows to access a pair of a function value and a Boolean for a given point. The Boolean indicates whether the function value could be retrieved correctly. This function generates the interpolated function value as the weighted sum of the values corresponding to each point of the point/coordinate pairs in the range `[first, beyond)`. `function_value(q).second == true` for all points `q` of the point/coordinate pairs in the range `[first, beyond)`.

See Also
  `CGAL::Data_access<Map>`
  `CGAL::natural_neighbor_coordinates_2()`
  `CGAL::regular_neighbor_coordinates_2()`
  3D Surface Neighbor Coordinates Functions

`#include <CGAL/interpolation_functions.h>`

Examples:
  Interpolation/linear_interpolation_2.cpp.

template<class ForwardIterator , class Functor , class GradFunctor , class Traits >

Functor::result_type CGAL::quadratic_interpolation | ( | ForwardIterator | first,
|  | ForwardIterator | beyond,
|  | const typename std::iterator_traits< ForwardIterator >::value_type::second_type & | norm,
|  | const typename std::iterator_traits< ForwardIterator >::value_type::first_type & | p,
|  | Functor | function_value,
|  | GradFunctor | function_gradient,
|  | const Traits & | traits
| ) |  |

The function `quadratic_interpolation()` generates the interpolated function value as the weighted sum of the values plus a linear term in the gradient for each point of the point/coordinate pairs in the range `[first, beyond)`.

Parameters and Template Parameters

The same as for `sibson_c1_interpolation()` only that `Traits::FT` does not need to provide the square root operation.

See Also
  `InterpolationTraits`
  `GradientFittingTraits`
  `CGAL::Data_access<Map>`
  Sibson gradient fitting functions
  `CGAL::linear_interpolation()`
  `CGAL::Interpolation_traits_2<K>`
  `CGAL::Interpolation_gradient_fitting_traits_2<K>`
  `CGAL::natural_neighbor_coordinates_2()`
  `CGAL::regular_neighbor_coordinates_2()`
  3D Surface Neighbor Coordinates Functions

`#include <CGAL/interpolation_functions.h>`

template<class ForwardIterator , class Functor , class GradFunctor , class Traits >

std::pair< typename Functor::result_type,bool> CGAL::sibson_c1_interpolation | ( | ForwardIterator | first,
|  | ForwardIterator | beyond,
|  | const typename std::iterator_traits< ForwardIterator >::value_type::second_type & | norm,
|  | const typename std::iterator_traits< ForwardIterator >::value_type::first_type & | p,
|  | Functor | function_value,
|  | GradFunctor | function_gradient,
|  | const Traits & | traits
| ) |  |

The function `sibson_c1_interpolation()` generates the interpolated function value at the point `p`, using functors for the function values and the gradients, by applying Sibson's \( Z^1\) interpolant.

If the functor `function_gradient` cannot supply the gradient of a point, the function returns a pair where the Boolean is set to `false`. If the interpolation was successful, the pair contains the interpolated function value as first and `true` as second value.

Template Parameters

  Traits | must be a model of `InterpolationTraits`. The number type `FT` provided by `Traits` must support the square root operation `sqrt()`.
  ForwardIterator | must have as value type a pair associating a point to a (non-normalized) barycentric coordinate. More precisely, `std::iterator_traits<ForwardIterator>::value_type::first_type` is equivalent to `Traits::Point_d` and `std::iterator_traits<ForwardIterator>::value_type::second_type` is equivalent to `Traits::FT`.
  Functor | must be a functor where `Functor::argument_type` must be equivalent to `Traits::Point_d` and `Functor::result_type` is a pair of the function value type and a Boolean. The function value type must provide a multiplication and addition operation with the type `Traits::FT` as well as a constructor with argument `0`.
  GradFunctor | must be a functor where `GradFunctor::argument_type` must be equivalent to `Traits::Point_d` and `Functor::result_type` is a pair of the function's gradient type and a Boolean. The function gradient type must provide a multiplication operation with `Traits::Vector_d`.

A model of the functor types `Functor` (resp. `GradFunctor`) is provided by the struct `Data_access`. It must be instantiated accordingly with an associative container (e.g. `std::map`) having the point type as `key_type` and the function value type (resp. function gradient type) as `mapped_type`.

Parameters

  first,beyond | is the iterator range of the barycentric coordinates for the query point `p`.
  norm | is the normalization factor. `norm` \( \neq0\).
  p | is the point at which the interpolated function value is generated
  function_value | is a functor that allows to access the value of the interpolated function given a point. `function_value(q).second == true` for all points `q` of the point/coordinate pairs in the range `[first, beyond)`
  function_gradient | is a functor that allows to access the function gradient given a point.
  traits | is an instance of the traits class

See Also
  `InterpolationTraits`
  `GradientFittingTraits`
  `CGAL::Data_access<Map>`
  Sibson gradient fitting functions
  `CGAL::linear_interpolation()`
  `CGAL::Interpolation_traits_2<K>`
  `CGAL::Interpolation_gradient_fitting_traits_2<K>`
  `CGAL::natural_neighbor_coordinates_2()`
  `CGAL::regular_neighbor_coordinates_2()`
  3D Surface Neighbor Coordinates Functions

`#include <CGAL/interpolation_functions.h>`