Development of a general-purpose freehand graphics input front-end processor which provides sketch recognition services

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When this research started, we had already established a freehand curve identifier FSCI, which identifies a freehand curve as one of seven kinds of curve primitives : line, circle, circular arc, ellipse, elliptic arc, free closed curve, or free open curve, and had developed a freehand sketch input user interface based on FSCI. The aim of this research was to establish a framework which enables the freehand sketch input user interface to work as a front-end processor (FEP) for existing practical CAD applications, and to confirm the effectiveness of sketch input in practical design tasks. Through the research, we first made investigation on communication between the FEP and CAD applications and established a communication protocol that exchanges view port information, model space information and graphic primitive information. Then, we materialized a concrete prototype of the FEP as SKIT (Sketch Input Tracer) based on the established protocol. Finally, we made some experiments where we let SKIT work with two existing CAD applications, which were AutoCAD and Shade. The experimental results showed that users could make use of both of the intuitive sketch input interface by SKIIT and rich commands of CAD applications in seamless manners, and that the combination of SKIT and a practical CAD application functions as a practical sketch input CAD application. Future work will focus on conducting experiments to let SKIT work with some other different kinds of CAD applications and making quantitative and objective evaluations on the effectiveness of the sketch input interface.