feat: add RadialKDTreeInterpolatorFactory

* and RadialKDTreeInterpolator

src/main/java/net/imglib2/algorithm/interpolation/realrandomaccess/RadialKDTreeInterpolator.java

@@ -0,0 +1,82 @@
+package net.imglib2.algorithm.interpolation.realrandomaccess;
+
+import java.util.function.DoubleUnaryOperator;
+
+import net.imglib2.KDTree;
+import net.imglib2.RealPoint;
+import net.imglib2.RealRandomAccess;
+import net.imglib2.interpolation.InterpolatorFactory;
+import net.imglib2.neighborsearch.RadiusNeighborSearch;
+import net.imglib2.neighborsearch.RadiusNeighborSearchOnKDTree;
+import net.imglib2.type.numeric.NumericType;
+
+/**
+ * A {@link RealRandomAccess} for {@link KDTree}s using a radial function used by
+ * {@link RadialKDTreeInterpolatorFactory}.
+ *
+ * @author John Bogovic
+ */
+public class RadialKDTreeInterpolator<T extends NumericType<T>> extends RealPoint implements RealRandomAccess<T> {
+
+	protected static final double minThreshold = Double.MIN_VALUE * 1000;
+
+	protected final RadiusNeighborSearch<T> search;
+	protected final double maxRadius;
+	protected final double maxSquaredRadius;
+	protected final KDTree<T> tree;
+	protected final T value;
+	protected final T tmp;
+	protected final DoubleUnaryOperator squaredRadiusFunction;
+
+	public RadialKDTreeInterpolator(
+			final KDTree<T> tree,
+			final DoubleUnaryOperator squaredRadiusFunction,
+			final double maxRadius,
+			T t) {
+
+		super(tree.numDimensions());
+
+		this.squaredRadiusFunction = squaredRadiusFunction;
+		this.tree = tree;
+		this.search = new RadiusNeighborSearchOnKDTree<T>(tree);
+		this.maxRadius = maxRadius;
+		this.maxSquaredRadius = maxRadius * maxRadius;
+		this.value = t.copy();
+		this.tmp = t.copy();
+	}
+
+	public double getMaxRadius() {
+
+		return maxRadius;
+	}
+
+	@Override
+	public T get() {
+
+		value.setZero();
+		search.search(this, maxRadius, false);
+		if (search.numNeighbors() == 0)
+			return value;
+
+		for (int i = 0; i < search.numNeighbors(); ++i) {
+			// can't multiply the value returned
+			tmp.set(search.getSampler(i).get());
+			tmp.mul(squaredRadiusFunction.applyAsDouble(search.getSquareDistance(i)));
+			value.add(tmp);
+		}
+		return value;
+	}
+
+	@Override
+	public RadialKDTreeInterpolator<T> copy() {
+
+		return new RadialKDTreeInterpolator<T>(tree, squaredRadiusFunction, maxRadius, value);
+	}
+
+	@Override
+	public RadialKDTreeInterpolator<T> copyRealRandomAccess() {
+
+		return copy();
+	}
+
+}

src/main/java/net/imglib2/algorithm/interpolation/realrandomaccess/RadialKDTreeInterpolatorFactory.java

@@ -0,0 +1,47 @@
+package net.imglib2.algorithm.interpolation.realrandomaccess;
+
+import java.util.function.DoubleUnaryOperator;
+
+import net.imglib2.KDTree;
+import net.imglib2.RealInterval;
+import net.imglib2.RealRandomAccess;
+import net.imglib2.interpolation.InterpolatorFactory;
+import net.imglib2.type.numeric.NumericType;
+
+/**
+ * An {@link InterpolatorFactory} for {@link KDTree}s using a radial function.
+ * <p>
+ * The resulting {@link RealRandomAccess} produced by this InterpolatorFactory
+ * returns values as a linear combination of all points within a certain radius.
+ * The contribution of each point is weighted according to a function of its
+ * squared radius.
+ *
+ * @author John Bogovic
+ */
+public class RadialKDTreeInterpolatorFactory<T extends NumericType<T>> implements InterpolatorFactory<T, KDTree<T>> {
+
+	protected final double maxRadius;
+	protected final DoubleUnaryOperator squaredRadiusFunction;
+	protected final T val;
+
+	public RadialKDTreeInterpolatorFactory(
+			final DoubleUnaryOperator squaredRadiusFunction, final double maxRadius, T t) {
+
+		this.maxRadius = maxRadius;
+		this.squaredRadiusFunction = squaredRadiusFunction;
+		this.val = t;
+	}
+
+	@Override
+	public RadialKDTreeInterpolator<T> create(final KDTree<T> tree) {
+
+		return new RadialKDTreeInterpolator<T>(tree, squaredRadiusFunction, maxRadius, val);
+	}
+
+	@Override
+	public RealRandomAccess<T> create(final KDTree<T> tree, final RealInterval interval) {
+
+		return create(tree);
+	}
+
+}