public static DualMidpointSmoother chaikin(int iters) {
    return new DualMidpointSmoother(0.25, 0.75).setIters(iters);
  }
Returns a new smoother that does <a href="https://observablehq.com/@pamacha/chaikins-algorithm">Chaikin
Smoothing</a> {@code iters} times on the input line.
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/DualMidpointSmoother.java