3D MORPHING
In this page we explain about 3D morphing in general.
Morphing
We may start with a more general question: What is morphing?
Morphing is a name coined over a decade ago,
for animation sequences which display gradual transformation.
This word and concept has been used to
refer to transformations of images, polygons, and bodies divided to
tiny cubes (voxels), but we refer to polyhedral morphing.
3D morphing is the process of
gradual transformation between 3D bodies. We refer to
the 3D bodies which are represented polyhedrally, i.e.
by vertices, straight edges connecting them, and faces, each
consisting of a planar vertex set with the connecting edges.
This is the most common representation for 3D bodies in computer
graphics, and especially in modellers for 3D animation.
When the inputs are the beginning and the end polyhedron,
producing a 3D morphing sequence involves interpolating these inputs,
so that a polyhedron sequence results,
in which every polyhedron looks more like the end
polyhedron and less like the beginning, relative to the previous
polyhedron in the sequence.
Example
As an example of a gradual interpolation of 3D bodies,
think of the form changes of the bad terminator in the movie "Terminator 2",
although we're not sure if the sequences there involved
gradual transformation of 3D bodies or 2D images (we suspect
the latter).
In any case
this demonstrates the great effects that can be produced by
morphing.
Comparison
3D scenes which contain interpolated bodies
can achieve a lot more than their 2D conterparts. This is primarily
because the interpolated bodies can be displayed in different light
conditions, camera positions, color and texture varieties, without
changing anything regarding the morphing results, i.e. those
interpolated bodies. However, each such
change in a movie that contains 2D morphing, requires re-doing the
whole morphing process. The same interpolated bodies can be re-used
in completely different scenes without any further work, which isn't
the case with the interpolated 2D images.
Underground
We achieve the task of constructing 3D morphing sequences
with the Underground system.
There are a few difficulties that have to be overcome when trying
to construct 3D morphing sequences with polyhedral bodies (creating
sequences from bodies represented as voxels is easier, but
not practical- they are harder to come by in the first place,
and harder to display and manipulate once generated).
Creating the sequences in the first place is hard,
and creating sequences which look pleasing, in a reasonable amount of
time, is even harder. Another common problem, which we address
in the Underground system, is
the specification of fitting information- how to fit certain
parts in one body, to change into certain parts in the other body.
