Abstract

Defining how 3D models respond to user actions is a crucial step in
building an interactive 3D world. Unfortunately, existing tools make
it very difficult for interaction designers to assign responses to any
part of a 3D model that is not a pre-defined group of polygons. This
is particularly problematic for applications that use image-based
models or models where most of the detail is in the model's texture
map. We present a flexible and easy-to-use technique that overcomes
this problem by allowing a designer to specify interaction surfaces,
parts of the model he wants to respond to events, by painting them
onto the model. We capture the painted areas by projecting them onto a
2D interaction map. An interaction map is similar to a traditional
texture, but it specifies interaction surfaces instead of affecting a
model's appearance. We allow designers to name interaction surfaces
and then assign them responses to events both statically and at
run-time. In addition, designers can modify the size and shape of
interaction surfaces at run-time and can pass parameters to these
surfaces' responses by encoding them in the model's interaction
map.