Digital Image Morphing


We wished to combine some of the ease of use of Bier's SIGGRAPH 92 method with the speed of local triangle methods. Since the quality of the morph is quite subjective, we felt that allowing the artist to iterate quickly would be an important design goal.


In this approach we allow the artist to mark key areas with polylines and to drag them on the second image to match features. These polylines were used to produce a constrained Delauney triangulation of the image. Lines that were added in during the triangulation are treated as elastic mesh elements.

To produce the morph, the positions of the keyframe polylines are interpolated between the initial and end image. At each frame, the elastic mesh is relaxed to a minimum energy state. The texture on each triangle in the intial frame and the final frame are then color interpolated and displayed on the matching intermediate triangle in the morph frame.

Since the pixel interpolation is local to the triangle, it can be done very efficiently. The mesh relaxation is global, but contains few elements compared to the number of pixels and can also be solved quickly. And frame-to-frame coherence speeds convergence as well.

Mpegs of morphs are available online. Some of these morphs were done during a one day workshop for high school students sponsored by our group. Can you recognize the halfway mix of Barney and Elvis done by one of the students in the top right image?


Last update: January 7, 2000