In contrast to existing methods of metamorphosis based on interpolation schemes, space-time blending is a geometric operation of bounded blending performed in the higher-dimensional space. It provides transformations between shapes of different topology without necessarily establishing their alignment or correspondence. The original formulation of space-time blending has several problems: fast uncontrolled transition between shapes within the given time interval, generation of disconnected components, and lack of intuitive user control over the transformation process. We propose several techniques for more intuitive user control for space-time blending. The problem of the fast transition between the shapes is solved by the introduction of additional controllable affine transformations applied to initial objects in space-time. This gives more control to the user. The approach is further extended with the introduction of an additional non-linear deformation operation to the pure space-time blending. The proposed techniques have been implemented and tested within an industrial computer animation system. Moreover, this method can now be employed in real-time applications taking advantage of modern GPUs.