figure 1. modeling session in teddy. users create 3D models using simple sketching
operations.
tent. End users constructing 3D models are also supported by a number of
systems, including Google’s SketchUp
( http://sketchup.google.com/) and
modeling tools in SecondLife and Spore.
However, these systems use scaled-down versions of traditional interfaces
and still require a certain amount of
skill. This article introduces research
efforts at the University of Tokyo and
Brown University to make computer-graphics authoring accessible to more
casual users. To achieve this goal, the
author and his collaborators developed easy-to-use prototype systems
to create expressive computer graphics more quickly than with traditional
interfaces. Examples are sketch-based
3D modeling, clothing manipulation,
animation by performance, and 2D
shape manipulation. We discuss the
user interfaces and technical aspects
of these prototype systems, as well as
the lessons learned from their development, offering ideas for future research directions.
Most of our work is highly interactive and difficult to explain in written words and still images; please see
demonstration videos and prototype
systems at http://www-ui.is.s.u-tokyo.
ac.jp/~takeo.
figure 2. screenshot of teddy and sample 3D models created through the teddy system.
figure 3. using teddy to teach the concept of contour lines.
sketching 3D models
Creating a 3D model in a computer
(not necessarily on a screen) is the first
step in most 3D computer-graphics
applications yet is also the most difficult. Traditional interfaces for 3D
modeling programs trace their origins
to traditional pencil-and-paper professional drafting. Users place vertices
in 3D space by specifying x-, y-, and z-
coordinates in a three-view interface,
then create polygonal faces (individual
polygonal sides of a polyhedron) by
connecting these vertices. Alternatively, users start with a simple primitive (such as a sphere or cylinder) and
modify it by editing individual vertices
and edges. Many editing tools (such as
free-form deformation and Boolean
operations among solids) are available for designing complicated shapes
from simple primitives. Although they
might be appropriate for trained professionals designing precise models,
they are generally too difficult for first-time users trying to quickly generate
meaningful models.