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

在本研究开始时，我们已经建立了一种写意曲线标识符FSCI，将写意曲线识别为直线、圆、圆弧、椭圆、椭圆弧、自由闭合曲线、自由开放曲线等7种曲线基元之一，并开发了基于FSCI的写意草图输入用户界面。本研究的目的是建立一个框架，使手绘草图输入用户界面能够作为现有实际CAD应用程序的前端处理器（FEP），并确认草图输入在实际设计任务中的有效性。通过研究，我们首先对FEP与CAD应用程序之间的通信进行了探讨，并建立了一个交换视图端口信息、模型空间信息和图形原语信息的通信协议。然后，我们根据建立的协议将FEP的具体原型物化为SKIT （Sketch Input Tracer）。最后，我们做了一些实验，让SKIT与两个现有的CAD应用程序一起工作，这两个应用程序是AutoCAD和Shade。实验结果表明，用户可以无缝地使用SKIT直观的草图输入界面和CAD应用程序丰富的命令，SKIT与实际CAD应用程序的结合可以实现实用的草图输入CAD应用程序。未来的工作将集中在进行实验，让SKIT与其他不同类型的CAD应用程序一起工作，并对草图输入界面的有效性进行定量和客观的评估。

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.