private void SetOpacityTransferFunction()
{
_opacityTransferFunction.RemoveAllPoints();
_opacityTransferFunction.AddPoint(_volumeLayer.GetWindowLeft(), 0.0);
_opacityTransferFunction.AddPoint(
_volumeLayer.GetRescaledLevel(),
(double)_volumeLayer.TissueSettings.Opacity);
_opacityTransferFunction.AddPoint(_volumeLayer.GetWindowRight(), 0.0);
}