To appear in NPAR 2000.
The problem of interactively creating 3D scenes from 2D input is a compelling one, and recent progress has been exciting. We present our system, Harold, which combines ideas from existing techniques and introduces new concepts to make an interactive system for creating 3D worlds. The interface paradigm in Harold is drawing: all objects are created simply by drawing them with a 2D input device. Most of the 3D objects in Harold are collections of planar strokes that are reoriented in a view-dependent way as the camera moves through the world. Virtual worlds created in Harold are rendered with a stroke-based system so that a world will maintain a hand-drawn appearance as the user navigates through it. Harold is not suitable for representing certain classes of 3D objects, especially geometrically regular or extremely asymmetric objects. However, Harold supports a large enough class of objects that a user can rapidly create expressive and visually rich 3D worlds.