/// <summary>
///
/// </summary>
/// <param name="level"></param>
/// <param name="itemInterval"></param>
private void ComputeInterval(int level, Interval itemInterval)
{
double size = DoubleBits.PowerOf2(level);
_pt = Math.Floor(itemInterval.Min / size) * size;
_interval.Init(_pt, _pt + size);
//_interval = Interval.Create(_pt, _pt + size);
}
