Building geometric models with hand-drawn sketches

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1998.Includes bibliographical references (p. 49-51).Architects work on drawings and models, not buildings. Today, in many architectural practices, drawings and models are produced in digital format using Computer-aided Design (CAD) tools. Unquestionably, digital media have changed the way in which many architects perform their day to day activities. But these changes have been limited to the more prosaic aspects of practice. To be sure, CAD systems have made the daily operations of many design offices more efficient; nevertheless, they have been of little use - and indeed are often a hindrance - in situations where the task at hand is more conjectural and speculative in nature, as it is during the early stages of a project. Well-intentioned efforts to insinuate CAD into these aspects of practice have only served to reveal the incongruities between the demands of designer and the configuration of the available tools. One of the chief attributes of design practice is that it is action performed at a distance through the agency of representations. This fundamental trait implies that we have to understand how computers help architects describe buildings if we are to understand how they might help architects design buildings. As obvious as this claim might seem, CAD programs can be almost universally characterized by a tacit denigration of visual representation. In this thesis, I examine properties of design drawings that make them useful to architects. I go on to describe a computer program that I have written that allows a designer to build geometric models using freehand sketches. This program illustrates that it is possible to design a software tool in a way that profits from, rather than negates, the power of visual representations.by Ewan E. Branda.M.S

Implementing non-photorealistic rendreing enhancements with real-time performance

We describe quality and performance enhancements, which work in real-time, to all well-known Non-photorealistic (NPR) rendering styles for use in an interactive context. These include Comic rendering, Sketch rendering, Hatching and Painterly rendering, but we also attempt and justify a widening of the established definition of what is considered NPR. In the individual Chapters, we identify typical stylistic elements of the different NPR styles. We list problems that need to be solved in order to implement the various renderers. Standard solutions available in the literature are introduced and in all cases extended and optimised. In particular, we extend the lighting model of the comic renderer to include a specular component and introduce multiple inter-related but independent geometric approximations which greatly improve rendering performance. We implement two completely different solutions to random perturbation sketching, solve temporal coherence issues for coal sketching and find an unexpected use for 3D textures to implement hatch-shading. Textured brushes of painterly rendering are extended by properties such as stroke-direction and texture, motion, paint capacity, opacity and emission, making them more flexible and versatile. Brushes are also provided with a minimal amount of intelligence, so that they can help in maximising screen coverage of brushes. We furthermore devise a completely new NPR style, which we call super-realistic and show how sample images can be tweened in real-time to produce an image-based six degree-of-freedom renderer performing at roughly 450 frames per second. Performance values for our other renderers all lie between 10 and over 400 frames per second on homePC hardware, justifying our real-time claim. A large number of sample screen-shots, illustrations and animations demonstrate the visual fidelity of our rendered images. In essence, we successfully achieve our attempted goals of increasing the creative, expressive and communicative potential of individual NPR styles, increasing performance of most of them, adding original and interesting visual qualities, and exploring new techniques or existing ones in novel ways.KMBT_363Adobe Acrobat 9.54 Paper Capture Plug-i