A projective approach to computer-aided drawing
Name
49562099-MIT.pdf
Description
Full printable version
Size
13.39 MB
Format
Adobe PDF
Checksum (MD5)
9e713da4586b3c67cc585425c612f737
Author(s)
Tolba, Osama S., 1962-
Advisor(s)
Julie Dorsey and Leonard McMillan.
Date Issued
2001
Publisher
Massachusetts Institute of Technology
Abstract
I present a novel drawing system for composing and rendering perspective scenes. The proposed approach uses a projective two-dimensional representation for primitives rather than a conventional three-dimensional description. This representation is based on points that lie on the surface of a unit sphere centered at the viewpoint. It allows drawings to be composed with the same ease as traditional illustrations, while providing many of the advantages of a three-dimensional model. I describe a range of user-interface tools and interaction techniques that give the drawing system its three-dimensional-like capabilities. The system provides vanishing point guides and perspective grids to aid in drawing freehand strokes and composing perspective scenes. The system also has tools for intuitive navigation of a virtual camera, as well as methods for manipulating drawn primitives so that they appear to undergo three-dimensional translations and rotations. The new representation also supports automatic shading of primitives using either realistic or non-photorealistic styles. My system supports drawing and shading of extrusion surfaces with automatic hidden surface removal and emphasized silhouettes. Casting shadows from an infinite light source is also possible with minimal user intervention. I describe a method for aligning a sketch drawn outside the system using its vanishing points, allowing the integration of computer sketching and freehand sketching on paper in an iterative manner. Photographs and scanned drawings are applied to drawing primitives using conventional texture-mapping techniques, thereby enriching drawings and providing another way of incorporating hand-drawn images. I demonstrate the system with a variety of drawings.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2001.
Includes bibliographical references (p. 92-95).
Subjects
Architecture.
MIT Department
Massachusetts Institute of Technology. Department of Architecture
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