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Diffstat (limited to 'src/main/java/org/apache/commons/math3/analysis/interpolation/MicrosphereProjectionInterpolator.java')
| -rw-r--r-- | src/main/java/org/apache/commons/math3/analysis/interpolation/MicrosphereProjectionInterpolator.java | 164 |
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diff --git a/src/main/java/org/apache/commons/math3/analysis/interpolation/MicrosphereProjectionInterpolator.java b/src/main/java/org/apache/commons/math3/analysis/interpolation/MicrosphereProjectionInterpolator.java new file mode 100644 index 0000000..28f5b26 --- /dev/null +++ b/src/main/java/org/apache/commons/math3/analysis/interpolation/MicrosphereProjectionInterpolator.java @@ -0,0 +1,164 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.commons.math3.analysis.interpolation; + +import org.apache.commons.math3.analysis.MultivariateFunction; +import org.apache.commons.math3.exception.DimensionMismatchException; +import org.apache.commons.math3.exception.NoDataException; +import org.apache.commons.math3.exception.NotPositiveException; +import org.apache.commons.math3.exception.NullArgumentException; +import org.apache.commons.math3.random.UnitSphereRandomVectorGenerator; + +/** + * Interpolator that implements the algorithm described in + * <em>William Dudziak</em>'s + * <a href="http://www.dudziak.com/microsphere.pdf">MS thesis</a>. + * + * @since 3.6 + */ +public class MicrosphereProjectionInterpolator + implements MultivariateInterpolator { + /** Brightness exponent. */ + private final double exponent; + /** Microsphere. */ + private final InterpolatingMicrosphere microsphere; + /** Whether to share the sphere. */ + private final boolean sharedSphere; + /** Tolerance value below which no interpolation is necessary. */ + private final double noInterpolationTolerance; + + /** + * Create a microsphere interpolator. + * + * @param dimension Space dimension. + * @param elements Number of surface elements of the microsphere. + * @param exponent Exponent used in the power law that computes the + * @param 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 {@code background} value will + * be returned instead. + * @param darkThreshold Value of the illumination below which a facet is + * considered dark. + * @param background Value returned when the {@code maxDarkFraction} + * threshold is exceeded. + * @param sharedSphere Whether the sphere can be shared among the + * interpolating function instances. If {@code true}, the instances + * will share the same data, and thus will <em>not</em> be thread-safe. + * @param noInterpolationTolerance When the distance between an + * interpolated point and one of the sample points is less than this + * value, no interpolation will be performed (the value of the sample + * will be returned). + * @throws org.apache.commons.math3.exception.NotStrictlyPositiveException + * if {@code dimension <= 0} or {@code elements <= 0}. + * @throws NotPositiveException if {@code exponent < 0}. + * @throws NotPositiveException if {@code darkThreshold < 0}. + * @throws org.apache.commons.math3.exception.OutOfRangeException if + * {@code maxDarkFraction} does not belong to the interval {@code [0, 1]}. + */ + public MicrosphereProjectionInterpolator(int dimension, + int elements, + double maxDarkFraction, + double darkThreshold, + double background, + double exponent, + boolean sharedSphere, + double noInterpolationTolerance) { + this(new InterpolatingMicrosphere(dimension, + elements, + maxDarkFraction, + darkThreshold, + background, + new UnitSphereRandomVectorGenerator(dimension)), + exponent, + sharedSphere, + noInterpolationTolerance); + } + + /** + * Create a microsphere interpolator. + * + * @param microsphere Microsphere. + * @param exponent Exponent used in the power law that computes the + * weights (distance dimming factor) of the sample data. + * @param sharedSphere Whether the sphere can be shared among the + * interpolating function instances. If {@code true}, the instances + * will share the same data, and thus will <em>not</em> be thread-safe. + * @param noInterpolationTolerance When the distance between an + * interpolated point and one of the sample points is less than this + * value, no interpolation will be performed (the value of the sample + * will be returned). + * @throws NotPositiveException if {@code exponent < 0}. + */ + public MicrosphereProjectionInterpolator(InterpolatingMicrosphere microsphere, + double exponent, + boolean sharedSphere, + double noInterpolationTolerance) + throws NotPositiveException { + if (exponent < 0) { + throw new NotPositiveException(exponent); + } + + this.microsphere = microsphere; + this.exponent = exponent; + this.sharedSphere = sharedSphere; + this.noInterpolationTolerance = noInterpolationTolerance; + } + + /** + * {@inheritDoc} + * + * @throws DimensionMismatchException if the space dimension of the + * given samples does not match the space dimension of the microsphere. + */ + public MultivariateFunction interpolate(final double[][] xval, + final double[] yval) + throws DimensionMismatchException, + NoDataException, + NullArgumentException { + if (xval == null || + yval == null) { + throw new NullArgumentException(); + } + if (xval.length == 0) { + throw new NoDataException(); + } + if (xval.length != yval.length) { + throw new DimensionMismatchException(xval.length, yval.length); + } + if (xval[0] == null) { + throw new NullArgumentException(); + } + final int dimension = microsphere.getDimension(); + if (dimension != xval[0].length) { + throw new DimensionMismatchException(xval[0].length, dimension); + } + + // Microsphere copy. + final InterpolatingMicrosphere m = sharedSphere ? microsphere : microsphere.copy(); + + return new MultivariateFunction() { + /** {inheritDoc} */ + public double value(double[] point) { + return m.value(point, + xval, + yval, + exponent, + noInterpolationTolerance); + } + }; + } +} |