Testing ground for union optimization.

TestingGround.cs

using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using GeoAPI.Geometries;
using NetTopologySuite;
using NetTopologySuite.IO;
using NetTopologySuite.Operation.Union;

namespace TestingGround
{
    class Program
    {
        static void Main(string[] args)
        {
            // functionally equivalent to a redux version of PackedCoordinateSequenceFactory that
            // can only create 2-dimensional x/y sequences... it also uses a custom struct instead
            // of paired doubles, which seems to be a benefit.
            ICoordinateSequenceFactory csf = new SuperCoordSeqFactory();
            IGeometryFactory fac = NtsGeometryServices.Instance.CreateGeometryFactory(csf);

            // Data originally grabbed from ftp://ftp2.census.gov/geo/tiger/TIGER2015/TRACT/
            const string BiggestState = @"N:\media\datasets\TIGER\2015\tl_2015_48_tract";
            const string BigState = @"N:\media\datasets\TIGER\2015\tl_2015_23_tract";
            const string WholeCountry = @"N:\media\datasets\TIGER\2015";
            var geoms = Directory.EnumerateFiles(BigState, "*.shp", SearchOption.AllDirectories)
                                 .AsParallel()
                                 .SelectMany(path => new ShapefileReader(path, fac).Cast<IGeometry>())
                                 .ToList();

            Stopwatch sw = Stopwatch.StartNew();
            var unionResult = UnaryUnionOp.Union(geoms);
            sw.Stop();
            Console.WriteLine("Took {0} seconds.", sw.ElapsedTicks / (double)Stopwatch.Frequency);
            Console.ReadLine();
        }
    }
}