(1) automatically generates 2D Images if Z-dimension is set less or equal 1
In such case ( a single slice ) the corresponding object can be interpreted both as 2D and 3D image. From the ImageGenerator, in its current version, no single-slice 3D images can be generated.
(2) provides no option of creating an 'empty segmentation', i.e.
return an image with same geometry as a given reference image, user specified type and filled by a specified value
template< typename TPixelType> static mitk::Image::Pointer GenerateImageFromReference( mitk::Image::Pointer reference_image, TPixelType fill_value )