抄録
We have developed the computer assisted instruction system which aims to support mastering fundamental skills of machine drawing through observation on 3-dimensional virtual models reflecting incorrectness of third angle projections provided by learners. Since the system was constructed on the premise that the work is performed with CAD (computer aided design) software, it could not be used at the initial stage of education on machine drawing. In this study, the function to deal with handwritten drawing was implemented to the system in order to improve the usability at various situations in education. Manual drafting projections were converted into bitmap images and the coordinate values of the endpoints of each segment were determined with consideration for discrepancies resulted from digitization. In addition, 3-dimensional geometries generated from provided projections were displayed by using the HTML5 (hypertext markup language, revision 5) so that no special environments except of web browsers were required for learning. Usability of the improved system was demonstrated by execution examples.
