public static long encodeFlatLocation(double lon, double lat) {
    double worldX = getWorldX(lon) + 1;
    double worldY = getWorldY(lat) + 1;
    long x = (long) (worldX * HALF_QUANTIZED_WORLD_SIZE);
    long y = (long) (worldY * HALF_QUANTIZED_WORLD_SIZE);
    return (x << 32) | (y & LOWER_32_BIT_MASK);
  }
Returns a latitude/longitude coordinate encoded into a single 64-bit long for storage in a {@link LongLongMap} that
can be decoded using {@link #decodeWorldX(long)} and {@link #decodeWorldY(long)}.
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/GeoUtils.java