The line drawing editor, an experiment in computer vision

Abstract

A computer program, the Line Drawing Editor (LDE), that allows convenient modification of computer representations of simple line drawings has been designed and implemented. The distinguishing feature of the LDE from the multitude of interactive graphics programs that accomplish the same function is the use of a computer controlled TV camera for input and program control rather than conventional interactive input devices such as light pens or data tablets. A graphical editing language allows the LDE user to indicate, by marking the drawing in appropriate fashion, the changes that are to be made. The drawing, which was generated on a hardcopy output device, with the added edit information is placed in front of the camera. In successive phases the LDE computes a two dimensional homogeneous transformation relating the viewed drawing and its computer description, locates the lines added to the drawing, parses the added lines according to the edit language and finally uses this information to update the drawing description.