Make scene returns a list of levels - but makes them mutually distinct.
So if cutoff 0.1, 0.2, then 0.1<= x < 0.2 is an roi, not > 0.1 and > 0.2.
Different than contour3d as these are mutually exclusive levels.
makeScene(data, cutoffs, alpha, cols)- 3D array of values (can be nifti-class)
- series of levels to be created
- alpha levels for each contour
- colors for each contour
scene with multiple objects - can be passed to write4D