The 3D visualization of models seems to be broken since MITK 2014.03 when showing objects with opacity.
Some of the error seem to fixed when activating "depth sorting" in the data node property but this is only a visualization fix for a single item. Having multiple items drawn the depth perception is totally incorrect. Objects that are further away from the viewer look closer to the camera than others. Additionally some triangles are displayed transparent, other don't.
Workflow:
load vtk or stl file
load binary image and generate polygon model (normal/smoothed)
move 3D view and observe incorrectly displayed triangles in surface mode.
Result:
The visualization shows broken triangles in the Mesh. Also the depth perception seems to be wrong when loading multiple objects. This can be observed when moving the objects over each other.
Also sometimes the first surface side does vanish.
Attached you find 2 teeth. Best load both together and set transparency to 50% to perceive the face and depth problem.