"Sketch Recognition for Computer-Aided Design"

by Christopher F. Herot

Summary

This paper talks about free-hand sketching where inferences can be drawn from user actions.

In the first step, raw data is converted into a list of lines and curves by utilizing speed information to make interpretation of the user's intent. Corners are the intersection of two lines. Curves are fit to B-spline, smoothness is a function of speed. Then the output of line-curve finder is passed to a program the processes overtracing, adding a thickness parameter. The next level of interpretation is performed by the latching program which eliminates excess points. The latching radius is determined by speed, line length and density around each point.

Drawing style is important, suitable parameters can be determined for describing drawing styles. The sequence of drawing is also important. Adjustment of parameters can be done through editing operations (user repeatedly separates points joined by latcher, then the program can reduce the radius.)


Discussion

As a paper in 1970s, it is quite advanced. The adjustment of latching radius based on speed, length, density and editing operations is interesting.