| Designers typically sketch during concept development, and use computer modeling software to finalize their ideas. Both tools -- pencil and computer -- are well-suited for their task. Sketching is fast, fluid, and lets people explore ideas efficiently; computation lets users make structured, detailed digital models. But in practice, design does not progress directly from idea to final product. Instead, designers use paper, then software, return to sketching to develop or change concepts, turn back to the computer to implement changes, and so on. The transition between pencils and pixels is time-consuming.;Rapid fabrication and prototyping is a design area of increasing importance. Machines like laser cutters and 3D printers are becoming more common, and ordinary people are increasingly interested in these machines to design and make things. Current design software is made for professionals, not hobbyists. For avocational rapid prototyping machine users, software is the bottleneck.;This thesis presents Sketch It, Make It (SIMI ), a sketch-based modeling tool that lets non-experts design precise items for laser cutting by sketching. This removes the need to transition between sketches and formal CAD models. SIMI users make line work, issue commands, create geometric constraints, and produce "cut files" for production on a laser cutter -- entirely with a stylus. There are no modes (like line mode, erase mode) in SIMI: the meaning of user input is recognized by analyzing pen strokes and context.;Researchers have long sought to infer user intention by looking at sketches. The work presented in this thesis treats sketch recognition largely as an interaction design problem, rather than an artificial intelligence problem. Sketch-based techniques were developed to provide efficient user experience in specific contexts, including the laser cutter domain and the other sketch-based interaction techniques found in SIMI.;Two evaluations were used to measure SIMI's performance. First, a workshop involving sixty undergraduate architecture students was carried out. The students used SIMI and provided feedback on its technical performance and their own attitude about the software. Next, a task/tool analysis of SIMI and another common tool compares the steps needed to perform a simple design task. |
