SpatialInterpolator Class Reference

#include <spatial_interpolation.h>

Public Member Functions
	SpatialInterpolator (std::vector< Point2D > const &points, std::vector< double > const &values, int k_neighbors=12, double power=2.0)
	~SpatialInterpolator ()
double	Interpolate (double x, double y) const
void	Interpolate (std::vector< Point2D > const &query_points, std::vector< double > &results) const
KDTree const *	GetKDTree () const
PointCloud const &	GetPointCloud () const

Private Member Functions
	SpatialInterpolator (PointCloud const &cloud, KDTree *kdtree, std::vector< double > const &values, int k_neighbors, double power)

Private Attributes
PointCloud	m_cloud
std::vector< double >	m_values
KDTree *	m_kdtree
int	m_k_neighbors
double	m_power
bool	m_owns_kdtree

Static Private Attributes
static constexpr double	EPSILON = 1e-10

Friends
class	DualSpatialInterpolator

Detailed Description

Definition at line 86 of file spatial_interpolation.h.

Constructor & Destructor Documentation

SpatialInterpolator() [1/2]

SpatialInterpolator::SpatialInterpolator	(	std::vector< Point2D > const &	points,
		std::vector< double > const &	values,
		int	k_neighbors = 12,
		double	power = 2.0 )

Spatial Interpolation Using k-Nearest Neighbors and Inverse Distance Weighting

This file implements fast spatial interpolation using:

1. k-d tree for efficient nearest neighbor search (O(log n) per query)
2. Inverse Distance Weighting (IDW) for smooth interpolation
3. OpenMP parallelization for batch operations

ALGORITHM OVERVIEW:

For each query point (grid cell):

1. Find k nearest input points using k-d tree
2. Calculate weights based on inverse distance: w_i = 1 / dist_i^power
3. Interpolated value = Σ(w_i * value_i) / Σ(w_i)

KEY PARAMETERS TO TUNE:

• k_neighbors: Number of nearest points to use (typically 8-20)
  • Higher = smoother, more averaging
  • Lower = follows local variations more closely
• power: Exponent for inverse distance weighting (typically 1.0-4.0)
  • Higher = nearby points have more influence (sharper transitions)
  • Lower = distant points have more influence (smoother transitions)
  • power=2.0 is optimized for performance (avoids pow() function)

PERFORMANCE OPTIMIZATIONS:

• Special fast path for power=2.0 (uses squared distance directly, avoids sqrt/pow)
• OpenMP parallelization with guided scheduling
• Thread-local buffers to avoid allocation overhead
• Shared k-d tree between X and Y interpolation (DualSpatialInterpolator)

USAGE EXAMPLE:

std::vector<Point2D> input_points = {{0,0}, {10,0}, {5,10}}; std::vector<double> input_values = {1.0, 2.0, 1.5}; SpatialInterpolator interp(input_points, input_values, 12, 2.0); double result = interp.Interpolate(5.0, 5.0); // Interpolate at (5,5) Constructor: Build interpolator from points and values

Parameters

points	Input point coordinates (x, y)
values	Values at those points
k_neighbors	Number of nearest neighbors to use (default: 12)
power	IDW power parameter (default: 2.0)

Definition at line 59 of file spatial_interpolation.cpp.

~SpatialInterpolator()

SpatialInterpolator::~SpatialInterpolator

(

)

Definition at line 89 of file spatial_interpolation.cpp.

SpatialInterpolator() [2/2]

SpatialInterpolator::SpatialInterpolator ( PointCloud const & cloud, KDTree * kdtree, std::vector< double > const & values, int k_neighbors, double power )

private

Definition at line 80 of file spatial_interpolation.cpp.

Member Function Documentation

GetKDTree()

KDTree const * SpatialInterpolator::GetKDTree ( ) const

inline

Definition at line 104 of file spatial_interpolation.h.

GetPointCloud()

PointCloud const & SpatialInterpolator::GetPointCloud ( ) const

inline

Definition at line 107 of file spatial_interpolation.h.

Interpolate() [1/2]

double SpatialInterpolator::Interpolate	(	double	x,
		double	y ) const

Interpolate at a single query point

ALGORITHM:

1. Find k nearest neighbors using k-d tree
2. Calculate weight for each: w_i = 1 / distance_i^power
3. Return weighted average: Σ(w_i * value_i) / Σ(w_i)

SPECIAL CASES:

• If query point coincides with input point (dist < EPSILON): return exact value
• If power=2.0: optimized path using squared distances (faster)

Parameters

x	X coordinate of query point
y	Y coordinate of query point

Returns

Interpolated value

Definition at line 111 of file spatial_interpolation.cpp.

Referenced by Interpolate().

Interpolate() [2/2]

void SpatialInterpolator::Interpolate	(	std::vector< Point2D > const &	query_points,
		std::vector< double > &	results ) const

Definition at line 167 of file spatial_interpolation.cpp.

Friends And Related Symbol Documentation

DualSpatialInterpolator

friend class DualSpatialInterpolator

friend

Definition at line 120 of file spatial_interpolation.h.

Referenced by DualSpatialInterpolator.

Field Documentation

EPSILON

double SpatialInterpolator::EPSILON = 1e-10

staticconstexprprivate

Definition at line 117 of file spatial_interpolation.h.

Referenced by Interpolate(), and Interpolate().

m_cloud

PointCloud SpatialInterpolator::m_cloud

private

Definition at line 110 of file spatial_interpolation.h.

Referenced by GetPointCloud(), Interpolate(), Interpolate(), SpatialInterpolator(), and SpatialInterpolator().

m_k_neighbors

int SpatialInterpolator::m_k_neighbors

private

Definition at line 113 of file spatial_interpolation.h.

Referenced by Interpolate(), Interpolate(), SpatialInterpolator(), and SpatialInterpolator().

m_kdtree

KDTree* SpatialInterpolator::m_kdtree

private

Definition at line 112 of file spatial_interpolation.h.

Referenced by GetKDTree(), Interpolate(), Interpolate(), SpatialInterpolator(), SpatialInterpolator(), and ~SpatialInterpolator().

m_owns_kdtree

bool SpatialInterpolator::m_owns_kdtree

private

Definition at line 115 of file spatial_interpolation.h.

Referenced by SpatialInterpolator(), SpatialInterpolator(), and ~SpatialInterpolator().

m_power

double SpatialInterpolator::m_power

private

Definition at line 114 of file spatial_interpolation.h.

Referenced by Interpolate(), Interpolate(), SpatialInterpolator(), and SpatialInterpolator().

m_values

std::vector<double> SpatialInterpolator::m_values

private

Definition at line 111 of file spatial_interpolation.h.

Referenced by Interpolate(), Interpolate(), SpatialInterpolator(), and SpatialInterpolator().

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

• spatial_interpolation.h
• spatial_interpolation.cpp