We describe a computer graphics system that supports conceptual architectural design and analysis. We use as a starting point the traditional sketchbook drawings that architects use to experiment with various views, sections, and details. Rather than interpret or infer 3D structure from drawings, our system is designed to allow the designer to organize concept drawings in 3D, and gradually fuse a series of possibly geometrically-inconsistent sketches into a set of 3D strokes. Our system uses strokes and planar “canvases” as basic primitives; the basic mode of input is traditional 2D drawing. We introduce methods for the user to control stroke visibility and transfer strokes between canvases. We also introduce methods for the user to position and orient the canvases that have infinite extent. We demonstrate the use of the system to analyze existing structures and conceive new designs. 1

We present EverybodyLovesSketch, a gesture-based 3D curve sketching system for rapid ideation and visualization of 3D forms, aimed at a broad audience. We first analyze traditional perspective drawing in professional practice. We then design a system built upon the paradigm of ILoveSketch, a 3D curve drawing system for design professionals. The new system incorporates many interaction aspects of perspective drawing with judicious automation to enable novices with no perspective training to proficiently create 3D curve sketches. EverybodyLovesSketch supports a number of novel interactions: tick-based sketch plane selection, single view definition of arbitrary extrusion vectors, multiple extruded surface sketching, copy-and-project of 3D curves, freeform surface sketching, and an interactive perspective grid. Finally, we present a study involving 49 high school students (with no formal artistic training) who each learned and used the system over 11 days, which provides detailed insights into the popularity, power and usability of the various techniques, and shows our system to be easily learnt and effectively used, with broad appeal. ACM Classification: H.5.2 [Information Interfaces and

This paper describes, Napkin Sketch, a 3D sketching interface which attempts to support sketch-based artistic expression in 3D, mimicking some of the qualities of conventional sketching media and tools both in terms of physical properties and interaction experience. A portable tablet PC is used as the sketching platform, and handheld mixed reality techniques are employed to allow 3D sketches to be created on top of a physical napkin. Intuitive manipulation and navigation within the 3D design space is achieved by visually tracking the tablet PC with a camera and mixed reality markers. For artistic expression using sketch input, we improve upon the projective 3D sketching approach with a one stroke sketch plane definition technique. This coupled with the hardware setup produces a natural and fluid sketching experience.

The undersigned certify that they have read, and recommend to the Faculty of Graduate Studies for acceptance, a thesis entitled "3D Sketching and Collaborative Design with Napkin Sketch " submitted by Min Xin in partial fulfilment of the requirements of the degree of Master of Science.