Inverse distance interpolation. More...

#include <meshfree_interpolation.h>

Inheritance diagram for libMesh::InverseDistanceInterpolation< KDDim >:

Classes
class	PointListAdaptor
	This class adapts list of libMesh `Point` types for use in a nanoflann KD-Tree. More...

Public Types
enum	ParallelizationStrategy { SYNC_SOURCES = 0 , INVALID_STRATEGY }
	"ParallelizationStrategy" to employ. More...

Public Member Functions
	InverseDistanceInterpolation (const libMesh::Parallel::Communicator &comm_in, const unsigned int n_interp_pts=8, const Real power=2, const Number background_value=0., const Real background_eff_dist=-1.0)
	Constructor.

virtual void	clear () override
	Clears all internal data structures and restores to a pristine state.

virtual void	interpolate_field_data (const std::vector< std::string > &field_names, const std::vector< Point > &tgt_pts, std::vector< Number > &tgt_vals) const override
	Interpolate source data at target points.

void	print_info (std::ostream &os=libMesh::out) const
	Prints information about this object, by default to libMesh::out.

unsigned int	n_field_variables () const
	The number of field variables.

void	set_field_variables (std::vector< std::string > names)
	Defines the field variable(s) we are responsible for, and importantly their assumed ordering.

const std::vector< std::string > &	field_variables () const

std::vector< Point > &	get_source_points ()

std::vector< Number > &	get_source_vals ()

virtual void	add_field_data (const std::vector< std::string > &field_names, const std::vector< Point > &pts, const std::vector< Number > &vals)
	Sets source data at specified points.

virtual void	prepare_for_use ()
	Prepares data structures for use.

const Parallel::Communicator &	comm () const

processor_id_type	n_processors () const

processor_id_type	processor_id () const

Protected Types
typedef nanoflann::KDTreeSingleIndexAdaptor< nanoflann::L2_Simple_Adaptor< Real, PointListAdaptor< KDDim > >, PointListAdaptor< KDDim >, KDDim, std::size_t >	kd_tree_t

Protected Member Functions
virtual void	construct_kd_tree ()
	Build & initialize the KD tree, if needed.

virtual void	interpolate (const Point &pt, const std::vector< size_t > &src_indices, const std::vector< Real > &src_dist_sqr, std::vector< Number >::iterator &out_it) const
	Performs inverse distance interpolation at the input point from the specified points.

virtual void	gather_remote_data ()
	Gathers source points and values that have been added on other processors.

Protected Attributes
PointListAdaptor< KDDim >	_point_list_adaptor

std::unique_ptr< kd_tree_t >	_kd_tree

const Real	_half_power

const unsigned int	_n_interp_pts

const Number	_background_value

const Real	_background_eff_dist

std::vector< Number >	_vals
	Temporary work array.

ParallelizationStrategy	_parallelization_strategy

std::vector< std::string >	_names

std::vector< Point >	_src_pts

std::vector< Number >	_src_vals

const Parallel::Communicator &	_communicator

Detailed Description

template<unsigned int KDDim>
class libMesh::InverseDistanceInterpolation< KDDim >

Inverse distance interpolation.

Definition at line 179 of file meshfree_interpolation.h.

Member Typedef Documentation

◆ kd_tree_t

template<unsigned int KDDim>

typedef nanoflann::KDTreeSingleIndexAdaptor<nanoflann::L2_Simple_Adaptor<Real, PointListAdaptor<KDDim> >, PointListAdaptor<KDDim>, KDDim, std::size_t> libMesh::InverseDistanceInterpolation< KDDim >::kd_tree_t

protected

Definition at line 297 of file meshfree_interpolation.h.

Member Enumeration Documentation

◆ ParallelizationStrategy

enum libMesh::MeshfreeInterpolation::ParallelizationStrategy

inherited

"ParallelizationStrategy" to employ.

SYNC_SOURCES assumes that the data added on each processor are independent and relatively small. Calling the prepare_for_use() method with this ParallelizationStrategy will copy remote data from other processors, so all interpolation can be performed locally.

Other ParallelizationStrategy techniques will be implemented as needed.

Enumerator
SYNC_SOURCES
INVALID_STRATEGY

Definition at line 72 of file meshfree_interpolation.h.

72 {SYNC_SOURCES = 0,

73 INVALID_STRATEGY};

libMesh::MeshfreeInterpolation::INVALID_STRATEGY

@ INVALID_STRATEGY

Definition meshfree_interpolation.h:73

libMesh::MeshfreeInterpolation::SYNC_SOURCES

@ SYNC_SOURCES

Definition meshfree_interpolation.h:72

Constructor & Destructor Documentation

◆ InverseDistanceInterpolation()

template<unsigned int KDDim>

libMesh::InverseDistanceInterpolation< KDDim >::InverseDistanceInterpolation	(	const libMesh::Parallel::Communicator &	comm_in,
		const unsigned int	n_interp_pts = `8`,
		const Real	power = `2`,
		const Number	background_value = `0.`,
		const Real	background_eff_dist = `-1.0`
	)

inline

Constructor.

Takes the inverse distance power, which defaults to 2.

In addition to the conventional inverse distance interpolation, the user can specify a background value and an effective distance for the background value. A background value is corresponding to a virtual point that is always at a constant distance (which is set by background_eff_dist) from the target point. This is useful when the target point is far away from any source points and user wants an independent value for this kind of scenarios.

Definition at line 341 of file meshfree_interpolation.h.

                                                                        :
    MeshfreeInterpolation(comm_in),
#if LIBMESH_HAVE_NANOFLANN
    _point_list_adaptor(_src_pts),
#endif
    _half_power(power/2.0),
    _n_interp_pts(n_interp_pts),
    _background_value(background_value),
    _background_eff_dist(background_eff_dist)
  {}

Member Function Documentation

◆ add_field_data()

void libMesh::MeshfreeInterpolation::add_field_data	(	const std::vector< std::string > &	field_names,
		const std::vector< Point > &	pts,
		const std::vector< Number > &	vals
	)

virtualinherited

Sets source data at specified points.

Definition at line 74 of file meshfree_interpolation.C.

{
  libmesh_experimental();
  libmesh_assert_equal_to (field_names.size()*pts.size(), vals.size());
 
  // If we already have field variables, we assume we are appending.
  // that means the names and ordering better be identical!
  if (!_names.empty())
    {
      libmesh_error_msg_if(_names.size() != field_names.size(),
                           "ERROR:  when adding field data to an existing list the \nvariable list must be the same!");
 
      for (auto v : index_range(_names))
        libmesh_error_msg_if(_names[v] != field_names[v],
                             "ERROR:  when adding field data to an existing list the \nvariable list must be the same!");
    }
 
  // otherwise copy the names
  else
    _names = field_names;
 
  // append the data
  _src_pts.insert (_src_pts.end(),
                   pts.begin(),
                   pts.end());
 
  _src_vals.insert (_src_vals.end(),
                    vals.begin(),
                    vals.end());
 
  libmesh_assert_equal_to (_src_vals.size(),
                           _src_pts.size()*this->n_field_variables());
}

References libMesh::MeshfreeInterpolation::_names, libMesh::MeshfreeInterpolation::_src_pts, libMesh::MeshfreeInterpolation::_src_vals, and libMesh::index_range().

◆ clear()

template<unsigned int KDDim>

void libMesh::InverseDistanceInterpolation< KDDim >::clear ( )

overridevirtual

Clears all internal data structures and restores to a pristine state.

Reimplemented from libMesh::MeshfreeInterpolation.

Reimplemented in libMesh::RadialBasisInterpolation< KDDim, RBF >.

Definition at line 178 of file meshfree_interpolation.C.

{
#ifdef LIBMESH_HAVE_NANOFLANN
  // Delete the KD Tree and start fresh
  if (_kd_tree.get())
    _kd_tree.reset (nullptr);
#endif
 
  // Call  base class clear method
  MeshfreeInterpolation::clear();
}

References libMesh::MeshfreeInterpolation::clear().

Referenced by libMesh::RadialBasisInterpolation< KDDim, RBF >::clear().

◆ comm()

const Parallel::Communicator & libMesh::ParallelObject::comm ( ) const

inlineinherited

Returns: A reference to the Parallel::Communicator object used by this mesh.

Definition at line 97 of file parallel_object.h.

98 { return _communicator; }

libMesh::ParallelObject::_communicator

const Parallel::Communicator & _communicator

Definition parallel_object.h:120

References libMesh::ParallelObject::_communicator.

◆ construct_kd_tree()

template<unsigned int KDDim>

void libMesh::InverseDistanceInterpolation< KDDim >::construct_kd_tree ( )

protectedvirtual

Build & initialize the KD tree, if needed.

Definition at line 156 of file meshfree_interpolation.C.

{
#ifdef LIBMESH_HAVE_NANOFLANN
 
  LOG_SCOPE ("construct_kd_tree()", "InverseDistanceInterpolation<>");
 
  // Initialize underlying KD tree
  if (_kd_tree.get() == nullptr)
    _kd_tree = std::make_unique<kd_tree_t>
      (KDDim,
       _point_list_adaptor,
       nanoflann::KDTreeSingleIndexAdaptorParams(10 /* max leaf */));
 
  libmesh_assert (_kd_tree.get() != nullptr);
 
  _kd_tree->buildIndex();
#endif
}

References libMesh::libmesh_assert().

Referenced by libMesh::RadialBasisInterpolation< KDDim, RBF >::prepare_for_use().

◆ field_variables()

const std::vector< std::string > & libMesh::MeshfreeInterpolation::field_variables ( ) const

inlineinherited

Returns: The field variables as a read-only reference.

Definition at line 116 of file meshfree_interpolation.h.

117 { return _names; }

References libMesh::MeshfreeInterpolation::_names.

Referenced by libMesh::MeshfreeInterpolationFunction::operator()().

◆ gather_remote_data()

void libMesh::MeshfreeInterpolation::gather_remote_data ( )

protectedvirtualinherited

Gathers source points and values that have been added on other processors.

Note: The user is responsible for adding points only once per processor if this method is called. No attempt is made to identify duplicate points.

This method is virtual so that it can be overwritten or extended as required in derived classes.

Definition at line 131 of file meshfree_interpolation.C.

{
#ifndef LIBMESH_HAVE_MPI
 
  // no MPI -- no-op
  return;
 
#else
 
  // This function must be run on all processors at once
  parallel_object_only();
 
  LOG_SCOPE ("gather_remote_data()", "MeshfreeInterpolation");
 
  this->comm().allgather(_src_pts);
  this->comm().allgather(_src_vals);
 
#endif // LIBMESH_HAVE_MPI
}

References libMesh::MeshfreeInterpolation::_src_pts, libMesh::MeshfreeInterpolation::_src_vals, libMesh::Parallel::Communicator::allgather(), and libMesh::ParallelObject::comm().

Referenced by libMesh::MeshfreeInterpolation::prepare_for_use().

◆ get_source_points()

std::vector< Point > & libMesh::MeshfreeInterpolation::get_source_points ( )

inlineinherited

Returns: A writable reference to the point list.

Definition at line 122 of file meshfree_interpolation.h.

123 { return _src_pts; }

References libMesh::MeshfreeInterpolation::_src_pts.

Referenced by main(), and libMesh::MeshfreeSolutionTransfer::transfer().

◆ get_source_vals()

std::vector< Number > & libMesh::MeshfreeInterpolation::get_source_vals ( )

inlineinherited

Returns: A writable reference to the point list.

Definition at line 128 of file meshfree_interpolation.h.

129 { return _src_vals; }

References libMesh::MeshfreeInterpolation::_src_vals.

Referenced by main(), and libMesh::MeshfreeSolutionTransfer::transfer().

◆ interpolate()

template<unsigned int KDDim>

void libMesh::InverseDistanceInterpolation< KDDim >::interpolate	(	const Point &	pt,
		const std::vector< size_t > &	src_indices,
		const std::vector< Real > &	src_dist_sqr,
		std::vector< Number >::iterator &	out_it
	)		const

protectedvirtual

Performs inverse distance interpolation at the input point from the specified points.

Definition at line 257 of file meshfree_interpolation.C.

{
  // We explicitly assume that the input source points are sorted from closest to
  // farthest.  assert that assumption in DEBUG mode.
#ifdef DEBUG
  if (!src_dist_sqr.empty())
    {
      Real min_dist = src_dist_sqr.front();
 
      for (auto i : src_dist_sqr)
        {
          libmesh_error_msg_if(i < min_dist, i << " was less than min_dist = " << min_dist);
 
          min_dist = i;
        }
    }
#endif
 
 
  libmesh_assert_equal_to (src_dist_sqr.size(), src_indices.size());
 
 
  // Compute the interpolation weights & interpolated value
  const unsigned int n_fv = this->n_field_variables();
  _vals.resize(n_fv);
 
  std::fill (_vals.begin(), _vals.end(), Number(0.));
  Real tot_weight(0.);
  // The background value is optional
  // If background value option is enabled, add it to the total weight
  // If not, a "zero" weight is added
  if (_background_eff_dist > 0.0)
  {
    const Real background_wt = _background_eff_dist * _background_eff_dist > std::numeric_limits<Real>::epsilon()
                           ? 1.0 / std::pow(_background_eff_dist * _background_eff_dist, _half_power)
                           : 0.0;
    tot_weight += background_wt;
    std::fill (_vals.begin(), _vals.end(), Number(_background_value * background_wt));
  }
 
  std::vector<Real>::const_iterator src_dist_sqr_it=src_dist_sqr.begin();
  std::vector<size_t>::const_iterator src_idx_it=src_indices.begin();
 
  // Loop over source points
  while ((src_dist_sqr_it != src_dist_sqr.end()) &&
         (src_idx_it      != src_indices.end()))
    {
      libmesh_assert_greater_equal (*src_dist_sqr_it, 0.);
 
      const Real
        dist_sq = std::max(*src_dist_sqr_it, std::numeric_limits<Real>::epsilon()),
        weight = 1./std::pow(dist_sq, _half_power);
 
      tot_weight += weight;
 
      const std::size_t src_idx = *src_idx_it;
 
      // loop over field variables
      for (unsigned int v=0; v<n_fv; v++)
        {
          libmesh_assert_less (src_idx*n_fv+v, _src_vals.size());
          _vals[v] += _src_vals[src_idx*n_fv+v]*weight;
        }
 
      ++src_dist_sqr_it;
      ++src_idx_it;
    }
 
  // don't forget normalizing term & set the output buffer!
  for (unsigned int v=0; v<n_fv; v++, ++out_it)
    {
      _vals[v] /= tot_weight;
 
      *out_it = _vals[v];
    }
}

References libMesh::Real.

◆ interpolate_field_data()

template<unsigned int KDDim>

void libMesh::InverseDistanceInterpolation< KDDim >::interpolate_field_data	(	const std::vector< std::string > &	field_names,
		const std::vector< Point > &	tgt_pts,
		std::vector< Number > &	tgt_vals
	)		const

overridevirtual

Interpolate source data at target points.

Pure virtual, must be overridden in derived classes.

Implements libMesh::MeshfreeInterpolation.

Reimplemented in libMesh::RadialBasisInterpolation< KDDim, RBF >.

Definition at line 193 of file meshfree_interpolation.C.

{
  libmesh_experimental();
 
  // forcibly initialize, if needed
#ifdef LIBMESH_HAVE_NANOFLANN
  if (_kd_tree.get() == nullptr)
    const_cast<InverseDistanceInterpolation<KDDim> *>(this)->construct_kd_tree();
#endif
 
  LOG_SCOPE ("interpolate_field_data()", "InverseDistanceInterpolation<>");
 
  libmesh_assert_equal_to (field_names.size(), this->n_field_variables());
 
  // If we already have field variables, we assume we are appending.
  // that means the names and ordering better be identical!
  libmesh_error_msg_if(_names.size() != field_names.size(),
                       "ERROR:  when adding field data to an existing list the \nvariable list must be the same!");
 
  for (auto v : index_range(_names))
    libmesh_error_msg_if(_names[v] != field_names[v],
                         "ERROR:  when adding field data to an existing list the \nvariable list must be the same!");
 
  tgt_vals.resize (tgt_pts.size()*this->n_field_variables());
 
#ifdef LIBMESH_HAVE_NANOFLANN
  {
    std::vector<Number>::iterator out_it = tgt_vals.begin();
 
    const size_t num_results = std::min((size_t) _n_interp_pts, _src_pts.size());
 
    std::vector<size_t> ret_index(num_results);
    std::vector<Real>   ret_dist_sqr(num_results);
 
    for (const auto & tgt : tgt_pts)
      {
        const Real query_pt[] = { tgt(0), tgt(1), tgt(2) };
 
        _kd_tree->knnSearch(query_pt, num_results, ret_index.data(), ret_dist_sqr.data());
 
        this->interpolate (tgt, ret_index, ret_dist_sqr, out_it);
 
        // libMesh::out << "knnSearch(): num_results=" << num_results << "\n";
        // for (size_t i=0;i<num_results;i++)
        //   libMesh::out << "idx[" << i << "]="
        //       << std::setw(6) << ret_index[i]
        //       << "\t dist["<< i << "]=" << ret_dist_sqr[i]
        //       << "\t val[" << std::setw(6) << ret_index[i] << "]=" << _src_vals[ret_index[i]]
        //       << std::endl;
        // libMesh::out << "\n";
 
        // libMesh::out << "ival=" << _vals[0] << '\n';
      }
  }
#else
 
  libmesh_error_msg("ERROR: This functionality requires the library to be configured with nanoflann support!");
 
#endif
}

References libMesh::index_range(), and libMesh::Real.

Referenced by main().

◆ n_field_variables()

unsigned int libMesh::MeshfreeInterpolation::n_field_variables ( ) const

inlineinherited

The number of field variables.

Definition at line 103 of file meshfree_interpolation.h.

104 { return cast_int<unsigned int>(_names.size()); }

References libMesh::MeshfreeInterpolation::_names.

Referenced by libMesh::MeshfreeInterpolation::print_info().

◆ n_processors()

processor_id_type libMesh::ParallelObject::n_processors ( ) const

inlineinherited

Returns: The number of processors in the group.

Definition at line 103 of file parallel_object.h.

  {
    processor_id_type returnval =
      cast_int<processor_id_type>(_communicator.size());
    libmesh_assert(returnval); // We never have an empty comm
    return returnval;
  }

References libMesh::ParallelObject::_communicator, libMesh::libmesh_assert(), and libMesh::Parallel::Communicator::size().

◆ prepare_for_use()

void libMesh::MeshfreeInterpolation::prepare_for_use ( )

virtualinherited

Prepares data structures for use.

This method is virtual so that it can be overwritten or extended as required in derived classes.

Reimplemented in libMesh::RadialBasisInterpolation< KDDim, RBF >.

Definition at line 112 of file meshfree_interpolation.C.

{
  switch (_parallelization_strategy)
    {
    case SYNC_SOURCES:
      this->gather_remote_data();
      break;
 
    case INVALID_STRATEGY:
      libmesh_error_msg("Invalid _parallelization_strategy = " << _parallelization_strategy);
 
    default:
      // no preparation required for other strategies
      break;
    }
}

References libMesh::MeshfreeInterpolation::_parallelization_strategy, libMesh::MeshfreeInterpolation::gather_remote_data(), libMesh::MeshfreeInterpolation::INVALID_STRATEGY, and libMesh::MeshfreeInterpolation::SYNC_SOURCES.

Referenced by main(), libMesh::RadialBasisInterpolation< KDDim, RBF >::prepare_for_use(), and libMesh::MeshfreeSolutionTransfer::transfer().

◆ print_info()

void libMesh::MeshfreeInterpolation::print_info ( std::ostream & os = libMesh::out ) const

inherited

Prints information about this object, by default to libMesh::out.

Definition at line 38 of file meshfree_interpolation.C.

{
  os << "MeshfreeInterpolation"
     << "\n n_source_points()=" << _src_pts.size()
     << "\n n_field_variables()=" << this->n_field_variables()
     <<  "\n";
 
  if (this->n_field_variables())
    {
      os << "  variables = ";
      for (auto v : make_range(this->n_field_variables()))
        os << _names[v] << " ";
      os << std::endl;
    }
 
}

References libMesh::MeshfreeInterpolation::_names, libMesh::MeshfreeInterpolation::_src_pts, libMesh::make_range(), and libMesh::MeshfreeInterpolation::n_field_variables().

◆ processor_id()

processor_id_type libMesh::ParallelObject::processor_id ( ) const

inlineinherited

Returns: The rank of this processor in the group.

Definition at line 114 of file parallel_object.h.

115 { return cast_int<processor_id_type>(_communicator.rank()); }

libMesh::Parallel::Communicator::rank

processor_id_type rank() const

References libMesh::ParallelObject::_communicator, and libMesh::Parallel::Communicator::rank().

◆ set_field_variables()

void libMesh::MeshfreeInterpolation::set_field_variables ( std::vector< std::string > names )

inlineinherited

Defines the field variable(s) we are responsible for, and importantly their assumed ordering.

Definition at line 110 of file meshfree_interpolation.h.

template<unsigned int KDDim>

std::vector<Number> libMesh::InverseDistanceInterpolation< KDDim >::_vals

mutableprotected

Temporary work array.

Object level scope to avoid cache thrashing.

Definition at line 325 of file meshfree_interpolation.h.

The documentation for this class was generated from the following files:

include/mesh/triangulator_interface.h
include/solution_transfer/meshfree_interpolation.h
src/solution_transfer/meshfree_interpolation.C

Classes

Public Types

Public Member Functions

Protected Types

Protected Member Functions

Protected Attributes

Detailed Description

Member Typedef Documentation

◆ kd_tree_t

Member Enumeration Documentation

◆ ParallelizationStrategy

Constructor & Destructor Documentation

◆ InverseDistanceInterpolation()

Member Function Documentation

◆ add_field_data()

◆ clear()

◆ comm()

◆ construct_kd_tree()

◆ field_variables()

◆ gather_remote_data()

◆ get_source_points()

◆ get_source_vals()

◆ interpolate()

◆ interpolate_field_data()

◆ n_field_variables()

◆ n_processors()

◆ prepare_for_use()

◆ print_info()

◆ processor_id()

◆ set_field_variables()

Member Data Documentation

◆ _background_eff_dist

◆ _background_value

◆ _communicator

◆ _half_power

◆ _kd_tree

◆ _n_interp_pts

◆ _names

◆ _parallelization_strategy

◆ _point_list_adaptor

◆ _src_pts

◆ _src_vals

◆ _vals