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VR Sketchpad - Create Instant 3D Worlds by Sketching on a Transparent Window
    CAAD Futures CAAD Futures 2001, Bauke de Vries, Jos P. van Leeuwen, Henri H. Achten (eds). July, 2001, Eindhoven, the Netherlands, Kluwer Academic Publishers. pp. 161-172. 2001
    This paper describes VR Sketchpad, a pen-based computing environment for inputting and locating 3D objects in a virtual world. Designer can use the transparency layers to quickly trace and extract any image underlay from other application software. The 3D scene generation has three levels of complexity: simple extrusion of any drawn lines of shapes (i.e., straight or curved wall and column extrusion), solid modelling from a given geometric object representation (spheres, cones and boxes), and complex configuration with objects from graphics library (furniture layout).
    related projects:
    Back of an Envelope Design, SketchVR