Class InterpolatingMicrosphere

java.lang.Object
org.apache.commons.math3.analysis.interpolation.InterpolatingMicrosphere
Direct Known Subclasses:
InterpolatingMicrosphere2D
public class InterpolatingMicrosphere extends Object
Utility class for the MicrosphereProjectionInterpolator algorithm.
Since:
3.6

  • Field Details

    • microsphere

      private final List<InterpolatingMicrosphere.Facet> microsphere
      Microsphere.

    • microsphereData

      private final List<InterpolatingMicrosphere.FacetData> microsphereData
      Microsphere data.

    • dimension

      private final int dimension
      Space dimension.

    • size

      private final int size
      Number of surface elements.

    • maxDarkFraction

      private final double maxDarkFraction
      Maximum fraction of the facets that can be dark.

    • darkThreshold

      private final double darkThreshold
      Lowest non-zero illumination.

    • background

      private final double background
      Background value.

  • Constructor Details

    • InterpolatingMicrosphere

      protected InterpolatingMicrosphere(int dimension, int size, double maxDarkFraction, double darkThreshold, double background)
      Create an unitialiazed sphere. Sub-classes are responsible for calling the add(double[]) add method in order to initialize all the sphere's facets.
      Parameters:
      dimension - Dimension of the data space.
      size - Number of surface elements of the sphere.
      maxDarkFraction - Maximum fraction of the facets that can be dark. If the fraction of "non-illuminated" facets is larger, no estimation of the value will be performed, and the background value will be returned instead.
      darkThreshold - Value of the illumination below which a facet is considered dark.
      background - Value returned when the maxDarkFraction threshold is exceeded.
      Throws:
      NotStrictlyPositiveException - if dimension <= 0 or size <= 0.
      NotPositiveException - if darkThreshold < 0.
      OutOfRangeException - if maxDarkFraction does not belong to the interval [0, 1].

    • InterpolatingMicrosphere

      public InterpolatingMicrosphere(int dimension, int size, double maxDarkFraction, double darkThreshold, double background, UnitSphereRandomVectorGenerator rand)
      Create a sphere from randomly sampled vectors.
      Parameters:
      dimension - Dimension of the data space.
      size - Number of surface elements of the sphere.
      maxDarkFraction - Maximum fraction of the facets that can be dark. If the fraction of "non-illuminated" facets is larger, no estimation of the value will be performed, and the background value will be returned instead.
      darkThreshold - Value of the illumination below which a facet is considered dark.
      background - Value returned when the maxDarkFraction threshold is exceeded.
      rand - Unit vector generator for creating the microsphere.
      Throws:
      DimensionMismatchException - if the size of the generated vectors does not match the dimension set in the constructor.
      NotStrictlyPositiveException - if dimension <= 0 or size <= 0.
      NotPositiveException - if darkThreshold < 0.
      OutOfRangeException - if maxDarkFraction does not belong to the interval [0, 1].

    • InterpolatingMicrosphere

      protected InterpolatingMicrosphere(InterpolatingMicrosphere other)
      Copy constructor.
      Parameters:
      other - Instance to copy.

  • Method Details

    • copy

      public InterpolatingMicrosphere copy()
      Perform a copy.
      Returns:
      a copy of this instance.

    • getDimension

      public int getDimension()
      Get the space dimensionality.
      Returns:
      the number of space dimensions.

    • getSize

      public int getSize()
      Get the size of the sphere.
      Returns:
      the number of surface elements of the microspshere.

    • value

      public double value(double[] point, double[][] samplePoints, double[] sampleValues, double exponent, double noInterpolationTolerance)
      Estimate the value at the requested location. This microsphere is placed at the given point, contribution of the given samplePoints to each sphere facet is computed (illumination) and the interpolation is performed (integration of the illumination).
      Parameters:
      point - Interpolation point.
      samplePoints - Sampling data points.
      sampleValues - Sampling data values at the corresponding samplePoints.
      exponent - Exponent used in the power law that computes the weights (distance dimming factor) of the sample data.
      noInterpolationTolerance - When the distance between the point and one of the samplePoints is less than this value, no interpolation will be performed, and the value of the sample will just be returned.
      Returns:
      the estimated value at the given point.
      Throws:
      NotPositiveException - if exponent < 0.

    • add

      protected void add(double[] normal, boolean copy)
      Replace i-th facet of the microsphere. Method for initializing the microsphere facets.
      Parameters:
      normal - Facet's normal vector.
      copy - Whether to copy the given array.
      Throws:
      DimensionMismatchException - if the length of n does not match the space dimension.
      MaxCountExceededException - if the method has been called more times than the size of the sphere.

    • interpolate

      private double interpolate()
      Interpolation.
      Returns:
      the value estimated from the current illumination of the microsphere.

    • illuminate

      private void illuminate(double[] sampleDirection, double sampleValue, double weight)
      Illumination.
      Parameters:
      sampleDirection - Vector whose origin is at the interpolation point and tail is at the sample location.
      sampleValue - Data value of the sample.
      weight - Weight.

    • clear

      private void clear()
      Reset the all the facets data to zero.